📦 deps(thirdparty): update snapshots

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---
name: claude-d3js-skill
description: "This skill provides guidance for creating sophisticated, interactive data visualisations using d3.js."
risk: unknown
source: community
date_added: "2026-02-27"
---
# D3.js Visualisation
## Overview
This skill provides guidance for creating sophisticated, interactive data visualisations using d3.js. D3.js (Data-Driven Documents) excels at binding data to DOM elements and applying data-driven transformations to create custom, publication-quality visualisations with precise control over every visual element. The techniques work across any JavaScript environment, including vanilla JavaScript, React, Vue, Svelte, and other frameworks.
## When to use d3.js
**Use d3.js for:**
- Custom visualisations requiring unique visual encodings or layouts
- Interactive explorations with complex pan, zoom, or brush behaviours
- Network/graph visualisations (force-directed layouts, tree diagrams, hierarchies, chord diagrams)
- Geographic visualisations with custom projections
- Visualisations requiring smooth, choreographed transitions
- Publication-quality graphics with fine-grained styling control
- Novel chart types not available in standard libraries
**Consider alternatives for:**
- 3D visualisations - use Three.js instead
## Core workflow
### 1. Set up d3.js
Import d3 at the top of your script:
```javascript
import * as d3 from 'd3';
```
Or use the CDN version (7.x):
```html
<script src="https://d3js.org/d3.v7.min.js"></script>
```
All modules (scales, axes, shapes, transitions, etc.) are accessible through the `d3` namespace.
### 2. Choose the integration pattern
**Pattern A: Direct DOM manipulation (recommended for most cases)**
Use d3 to select DOM elements and manipulate them imperatively. This works in any JavaScript environment:
```javascript
function drawChart(data) {
if (!data || data.length === 0) return;
const svg = d3.select('#chart'); // Select by ID, class, or DOM element
// Clear previous content
svg.selectAll("*").remove();
// Set up dimensions
const width = 800;
const height = 400;
const margin = { top: 20, right: 30, bottom: 40, left: 50 };
// Create scales, axes, and draw visualisation
// ... d3 code here ...
}
// Call when data changes
drawChart(myData);
```
**Pattern B: Declarative rendering (for frameworks with templating)**
Use d3 for data calculations (scales, layouts) but render elements via your framework:
```javascript
function getChartElements(data) {
const xScale = d3.scaleLinear()
.domain([0, d3.max(data, d => d.value)])
.range([0, 400]);
return data.map((d, i) => ({
x: 50,
y: i * 30,
width: xScale(d.value),
height: 25
}));
}
// In React: {getChartElements(data).map((d, i) => <rect key={i} {...d} fill="steelblue" />)}
// In Vue: v-for directive over the returned array
// In vanilla JS: Create elements manually from the returned data
```
Use Pattern A for complex visualisations with transitions, interactions, or when leveraging d3's full capabilities. Use Pattern B for simpler visualisations or when your framework prefers declarative rendering.
### 3. Structure the visualisation code
Follow this standard structure in your drawing function:
```javascript
function drawVisualization(data) {
if (!data || data.length === 0) return;
const svg = d3.select('#chart'); // Or pass a selector/element
svg.selectAll("*").remove(); // Clear previous render
// 1. Define dimensions
const width = 800;
const height = 400;
const margin = { top: 20, right: 30, bottom: 40, left: 50 };
const innerWidth = width - margin.left - margin.right;
const innerHeight = height - margin.top - margin.bottom;
// 2. Create main group with margins
const g = svg.append("g")
.attr("transform", `translate(${margin.left},${margin.top})`);
// 3. Create scales
const xScale = d3.scaleLinear()
.domain([0, d3.max(data, d => d.x)])
.range([0, innerWidth]);
const yScale = d3.scaleLinear()
.domain([0, d3.max(data, d => d.y)])
.range([innerHeight, 0]); // Note: inverted for SVG coordinates
// 4. Create and append axes
const xAxis = d3.axisBottom(xScale);
const yAxis = d3.axisLeft(yScale);
g.append("g")
.attr("transform", `translate(0,${innerHeight})`)
.call(xAxis);
g.append("g")
.call(yAxis);
// 5. Bind data and create visual elements
g.selectAll("circle")
.data(data)
.join("circle")
.attr("cx", d => xScale(d.x))
.attr("cy", d => yScale(d.y))
.attr("r", 5)
.attr("fill", "steelblue");
}
// Call when data changes
drawVisualization(myData);
```
### 4. Implement responsive sizing
Make visualisations responsive to container size:
```javascript
function setupResponsiveChart(containerId, data) {
const container = document.getElementById(containerId);
const svg = d3.select(`#${containerId}`).append('svg');
function updateChart() {
const { width, height } = container.getBoundingClientRect();
svg.attr('width', width).attr('height', height);
// Redraw visualisation with new dimensions
drawChart(data, svg, width, height);
}
// Update on initial load
updateChart();
// Update on window resize
window.addEventListener('resize', updateChart);
// Return cleanup function
return () => window.removeEventListener('resize', updateChart);
}
// Usage:
// const cleanup = setupResponsiveChart('chart-container', myData);
// cleanup(); // Call when component unmounts or element removed
```
Or use ResizeObserver for more direct container monitoring:
```javascript
function setupResponsiveChartWithObserver(svgElement, data) {
const observer = new ResizeObserver(() => {
const { width, height } = svgElement.getBoundingClientRect();
d3.select(svgElement)
.attr('width', width)
.attr('height', height);
// Redraw visualisation
drawChart(data, d3.select(svgElement), width, height);
});
observer.observe(svgElement.parentElement);
return () => observer.disconnect();
}
```
## Common visualisation patterns
### Bar chart
```javascript
function drawBarChart(data, svgElement) {
if (!data || data.length === 0) return;
const svg = d3.select(svgElement);
svg.selectAll("*").remove();
const width = 800;
const height = 400;
const margin = { top: 20, right: 30, bottom: 40, left: 50 };
const innerWidth = width - margin.left - margin.right;
const innerHeight = height - margin.top - margin.bottom;
const g = svg.append("g")
.attr("transform", `translate(${margin.left},${margin.top})`);
const xScale = d3.scaleBand()
.domain(data.map(d => d.category))
.range([0, innerWidth])
.padding(0.1);
const yScale = d3.scaleLinear()
.domain([0, d3.max(data, d => d.value)])
.range([innerHeight, 0]);
g.append("g")
.attr("transform", `translate(0,${innerHeight})`)
.call(d3.axisBottom(xScale));
g.append("g")
.call(d3.axisLeft(yScale));
g.selectAll("rect")
.data(data)
.join("rect")
.attr("x", d => xScale(d.category))
.attr("y", d => yScale(d.value))
.attr("width", xScale.bandwidth())
.attr("height", d => innerHeight - yScale(d.value))
.attr("fill", "steelblue");
}
// Usage:
// drawBarChart(myData, document.getElementById('chart'));
```
### Line chart
```javascript
const line = d3.line()
.x(d => xScale(d.date))
.y(d => yScale(d.value))
.curve(d3.curveMonotoneX); // Smooth curve
g.append("path")
.datum(data)
.attr("fill", "none")
.attr("stroke", "steelblue")
.attr("stroke-width", 2)
.attr("d", line);
```
### Scatter plot
```javascript
g.selectAll("circle")
.data(data)
.join("circle")
.attr("cx", d => xScale(d.x))
.attr("cy", d => yScale(d.y))
.attr("r", d => sizeScale(d.size)) // Optional: size encoding
.attr("fill", d => colourScale(d.category)) // Optional: colour encoding
.attr("opacity", 0.7);
```
### Chord diagram
A chord diagram shows relationships between entities in a circular layout, with ribbons representing flows between them:
```javascript
function drawChordDiagram(data) {
// data format: array of objects with source, target, and value
// Example: [{ source: 'A', target: 'B', value: 10 }, ...]
if (!data || data.length === 0) return;
const svg = d3.select('#chart');
svg.selectAll("*").remove();
const width = 600;
const height = 600;
const innerRadius = Math.min(width, height) * 0.3;
const outerRadius = innerRadius + 30;
// Create matrix from data
const nodes = Array.from(new Set(data.flatMap(d => [d.source, d.target])));
const matrix = Array.from({ length: nodes.length }, () => Array(nodes.length).fill(0));
data.forEach(d => {
const i = nodes.indexOf(d.source);
const j = nodes.indexOf(d.target);
matrix[i][j] += d.value;
matrix[j][i] += d.value;
});
// Create chord layout
const chord = d3.chord()
.padAngle(0.05)
.sortSubgroups(d3.descending);
const arc = d3.arc()
.innerRadius(innerRadius)
.outerRadius(outerRadius);
const ribbon = d3.ribbon()
.source(d => d.source)
.target(d => d.target);
const colourScale = d3.scaleOrdinal(d3.schemeCategory10)
.domain(nodes);
const g = svg.append("g")
.attr("transform", `translate(${width / 2},${height / 2})`);
const chords = chord(matrix);
// Draw ribbons
g.append("g")
.attr("fill-opacity", 0.67)
.selectAll("path")
.data(chords)
.join("path")
.attr("d", ribbon)
.attr("fill", d => colourScale(nodes[d.source.index]))
.attr("stroke", d => d3.rgb(colourScale(nodes[d.source.index])).darker());
// Draw groups (arcs)
const group = g.append("g")
.selectAll("g")
.data(chords.groups)
.join("g");
group.append("path")
.attr("d", arc)
.attr("fill", d => colourScale(nodes[d.index]))
.attr("stroke", d => d3.rgb(colourScale(nodes[d.index])).darker());
// Add labels
group.append("text")
.each(d => { d.angle = (d.startAngle + d.endAngle) / 2; })
.attr("dy", "0.31em")
.attr("transform", d => `rotate(${(d.angle * 180 / Math.PI) - 90})translate(${outerRadius + 30})${d.angle > Math.PI ? "rotate(180)" : ""}`)
.attr("text-anchor", d => d.angle > Math.PI ? "end" : null)
.text((d, i) => nodes[i])
.style("font-size", "12px");
}
```
### Heatmap
A heatmap uses colour to encode values in a two-dimensional grid, useful for showing patterns across categories:
```javascript
function drawHeatmap(data) {
// data format: array of objects with row, column, and value
// Example: [{ row: 'A', column: 'X', value: 10 }, ...]
if (!data || data.length === 0) return;
const svg = d3.select('#chart');
svg.selectAll("*").remove();
const width = 800;
const height = 600;
const margin = { top: 100, right: 30, bottom: 30, left: 100 };
const innerWidth = width - margin.left - margin.right;
const innerHeight = height - margin.top - margin.bottom;
// Get unique rows and columns
const rows = Array.from(new Set(data.map(d => d.row)));
const columns = Array.from(new Set(data.map(d => d.column)));
const g = svg.append("g")
.attr("transform", `translate(${margin.left},${margin.top})`);
// Create scales
const xScale = d3.scaleBand()
.domain(columns)
.range([0, innerWidth])
.padding(0.01);
const yScale = d3.scaleBand()
.domain(rows)
.range([0, innerHeight])
.padding(0.01);
// Colour scale for values
const colourScale = d3.scaleSequential(d3.interpolateYlOrRd)
.domain([0, d3.max(data, d => d.value)]);
// Draw rectangles
g.selectAll("rect")
.data(data)
.join("rect")
.attr("x", d => xScale(d.column))
.attr("y", d => yScale(d.row))
.attr("width", xScale.bandwidth())
.attr("height", yScale.bandwidth())
.attr("fill", d => colourScale(d.value));
// Add x-axis labels
svg.append("g")
.attr("transform", `translate(${margin.left},${margin.top})`)
.selectAll("text")
.data(columns)
.join("text")
.attr("x", d => xScale(d) + xScale.bandwidth() / 2)
.attr("y", -10)
.attr("text-anchor", "middle")
.text(d => d)
.style("font-size", "12px");
// Add y-axis labels
svg.append("g")
.attr("transform", `translate(${margin.left},${margin.top})`)
.selectAll("text")
.data(rows)
.join("text")
.attr("x", -10)
.attr("y", d => yScale(d) + yScale.bandwidth() / 2)
.attr("dy", "0.35em")
.attr("text-anchor", "end")
.text(d => d)
.style("font-size", "12px");
// Add colour legend
const legendWidth = 20;
const legendHeight = 200;
const legend = svg.append("g")
.attr("transform", `translate(${width - 60},${margin.top})`);
const legendScale = d3.scaleLinear()
.domain(colourScale.domain())
.range([legendHeight, 0]);
const legendAxis = d3.axisRight(legendScale)
.ticks(5);
// Draw colour gradient in legend
for (let i = 0; i < legendHeight; i++) {
legend.append("rect")
.attr("y", i)
.attr("width", legendWidth)
.attr("height", 1)
.attr("fill", colourScale(legendScale.invert(i)));
}
legend.append("g")
.attr("transform", `translate(${legendWidth},0)`)
.call(legendAxis);
}
```
### Pie chart
```javascript
const pie = d3.pie()
.value(d => d.value)
.sort(null);
const arc = d3.arc()
.innerRadius(0)
.outerRadius(Math.min(width, height) / 2 - 20);
const colourScale = d3.scaleOrdinal(d3.schemeCategory10);
const g = svg.append("g")
.attr("transform", `translate(${width / 2},${height / 2})`);
g.selectAll("path")
.data(pie(data))
.join("path")
.attr("d", arc)
.attr("fill", (d, i) => colourScale(i))
.attr("stroke", "white")
.attr("stroke-width", 2);
```
### Force-directed network
```javascript
const simulation = d3.forceSimulation(nodes)
.force("link", d3.forceLink(links).id(d => d.id).distance(100))
.force("charge", d3.forceManyBody().strength(-300))
.force("center", d3.forceCenter(width / 2, height / 2));
const link = g.selectAll("line")
.data(links)
.join("line")
.attr("stroke", "#999")
.attr("stroke-width", 1);
const node = g.selectAll("circle")
.data(nodes)
.join("circle")
.attr("r", 8)
.attr("fill", "steelblue")
.call(d3.drag()
.on("start", dragstarted)
.on("drag", dragged)
.on("end", dragended));
simulation.on("tick", () => {
link
.attr("x1", d => d.source.x)
.attr("y1", d => d.source.y)
.attr("x2", d => d.target.x)
.attr("y2", d => d.target.y);
node
.attr("cx", d => d.x)
.attr("cy", d => d.y);
});
function dragstarted(event) {
if (!event.active) simulation.alphaTarget(0.3).restart();
event.subject.fx = event.subject.x;
event.subject.fy = event.subject.y;
}
function dragged(event) {
event.subject.fx = event.x;
event.subject.fy = event.y;
}
function dragended(event) {
if (!event.active) simulation.alphaTarget(0);
event.subject.fx = null;
event.subject.fy = null;
}
```
## Adding interactivity
### Tooltips
```javascript
// Create tooltip div (outside SVG)
const tooltip = d3.select("body").append("div")
.attr("class", "tooltip")
.style("position", "absolute")
.style("visibility", "hidden")
.style("background-color", "white")
.style("border", "1px solid #ddd")
.style("padding", "10px")
.style("border-radius", "4px")
.style("pointer-events", "none");
// Add to elements
circles
.on("mouseover", function(event, d) {
d3.select(this).attr("opacity", 1);
tooltip
.style("visibility", "visible")
.html(`<strong>${d.label}</strong><br/>Value: ${d.value}`);
})
.on("mousemove", function(event) {
tooltip
.style("top", (event.pageY - 10) + "px")
.style("left", (event.pageX + 10) + "px");
})
.on("mouseout", function() {
d3.select(this).attr("opacity", 0.7);
tooltip.style("visibility", "hidden");
});
```
### Zoom and pan
```javascript
const zoom = d3.zoom()
.scaleExtent([0.5, 10])
.on("zoom", (event) => {
g.attr("transform", event.transform);
});
svg.call(zoom);
```
### Click interactions
```javascript
circles
.on("click", function(event, d) {
// Handle click (dispatch event, update app state, etc.)
console.log("Clicked:", d);
// Visual feedback
d3.selectAll("circle").attr("fill", "steelblue");
d3.select(this).attr("fill", "orange");
// Optional: dispatch custom event for your framework/app to listen to
// window.dispatchEvent(new CustomEvent('chartClick', { detail: d }));
});
```
## Transitions and animations
Add smooth transitions to visual changes:
```javascript
// Basic transition
circles
.transition()
.duration(750)
.attr("r", 10);
// Chained transitions
circles
.transition()
.duration(500)
.attr("fill", "orange")
.transition()
.duration(500)
.attr("r", 15);
// Staggered transitions
circles
.transition()
.delay((d, i) => i * 50)
.duration(500)
.attr("cy", d => yScale(d.value));
// Custom easing
circles
.transition()
.duration(1000)
.ease(d3.easeBounceOut)
.attr("r", 10);
```
## Scales reference
### Quantitative scales
```javascript
// Linear scale
const xScale = d3.scaleLinear()
.domain([0, 100])
.range([0, 500]);
// Log scale (for exponential data)
const logScale = d3.scaleLog()
.domain([1, 1000])
.range([0, 500]);
// Power scale
const powScale = d3.scalePow()
.exponent(2)
.domain([0, 100])
.range([0, 500]);
// Time scale
const timeScale = d3.scaleTime()
.domain([new Date(2020, 0, 1), new Date(2024, 0, 1)])
.range([0, 500]);
```
### Ordinal scales
```javascript
// Band scale (for bar charts)
const bandScale = d3.scaleBand()
.domain(['A', 'B', 'C', 'D'])
.range([0, 400])
.padding(0.1);
// Point scale (for line/scatter categories)
const pointScale = d3.scalePoint()
.domain(['A', 'B', 'C', 'D'])
.range([0, 400]);
// Ordinal scale (for colours)
const colourScale = d3.scaleOrdinal(d3.schemeCategory10);
```
### Sequential scales
```javascript
// Sequential colour scale
const colourScale = d3.scaleSequential(d3.interpolateBlues)
.domain([0, 100]);
// Diverging colour scale
const divScale = d3.scaleDiverging(d3.interpolateRdBu)
.domain([-10, 0, 10]);
```
## Best practices
### Data preparation
Always validate and prepare data before visualisation:
```javascript
// Filter invalid values
const cleanData = data.filter(d => d.value != null && !isNaN(d.value));
// Sort data if order matters
const sortedData = [...data].sort((a, b) => b.value - a.value);
// Parse dates
const parsedData = data.map(d => ({
...d,
date: d3.timeParse("%Y-%m-%d")(d.date)
}));
```
### Performance optimisation
For large datasets (>1000 elements):
```javascript
// Use canvas instead of SVG for many elements
// Use quadtree for collision detection
// Simplify paths with d3.line().curve(d3.curveStep)
// Implement virtual scrolling for large lists
// Use requestAnimationFrame for custom animations
```
### Accessibility
Make visualisations accessible:
```javascript
// Add ARIA labels
svg.attr("role", "img")
.attr("aria-label", "Bar chart showing quarterly revenue");
// Add title and description
svg.append("title").text("Quarterly Revenue 2024");
svg.append("desc").text("Bar chart showing revenue growth across four quarters");
// Ensure sufficient colour contrast
// Provide keyboard navigation for interactive elements
// Include data table alternative
```
### Styling
Use consistent, professional styling:
```javascript
// Define colour palettes upfront
const colours = {
primary: '#4A90E2',
secondary: '#7B68EE',
background: '#F5F7FA',
text: '#333333',
gridLines: '#E0E0E0'
};
// Apply consistent typography
svg.selectAll("text")
.style("font-family", "Inter, sans-serif")
.style("font-size", "12px");
// Use subtle grid lines
g.selectAll(".tick line")
.attr("stroke", colours.gridLines)
.attr("stroke-dasharray", "2,2");
```
## Common issues and solutions
**Issue**: Axes not appearing
- Ensure scales have valid domains (check for NaN values)
- Verify axis is appended to correct group
- Check transform translations are correct
**Issue**: Transitions not working
- Call `.transition()` before attribute changes
- Ensure elements have unique keys for proper data binding
- Check that useEffect dependencies include all changing data
**Issue**: Responsive sizing not working
- Use ResizeObserver or window resize listener
- Update dimensions in state to trigger re-render
- Ensure SVG has width/height attributes or viewBox
**Issue**: Performance problems
- Limit number of DOM elements (consider canvas for >1000 items)
- Debounce resize handlers
- Use `.join()` instead of separate enter/update/exit selections
- Avoid unnecessary re-renders by checking dependencies
## Resources
### references/
Contains detailed reference materials:
- `d3-patterns.md` - Comprehensive collection of visualisation patterns and code examples
- `scale-reference.md` - Complete guide to d3 scales with examples
- `colour-schemes.md` - D3 colour schemes and palette recommendations
### assets/
Contains boilerplate templates:
- `chart-template.js` - Starter template for basic chart
- `interactive-template.js` - Template with tooltips, zoom, and interactions
- `sample-data.json` - Example datasets for testing
These templates work with vanilla JavaScript, React, Vue, Svelte, or any other JavaScript environment. Adapt them as needed for your specific framework.
To use these resources, read the relevant files when detailed guidance is needed for specific visualisation types or patterns.
## Limitations
- Use this skill only when the task clearly matches the scope described above.
- Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
- Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.
@@ -1,106 +0,0 @@
import { useEffect, useRef, useState } from 'react';
import * as d3 from 'd3';
function BasicChart({ data }) {
const svgRef = useRef();
useEffect(() => {
if (!data || data.length === 0) return;
// Select SVG element
const svg = d3.select(svgRef.current);
svg.selectAll("*").remove(); // Clear previous content
// Define dimensions and margins
const width = 800;
const height = 400;
const margin = { top: 20, right: 30, bottom: 40, left: 50 };
const innerWidth = width - margin.left - margin.right;
const innerHeight = height - margin.top - margin.bottom;
// Create main group with margins
const g = svg.append("g")
.attr("transform", `translate(${margin.left},${margin.top})`);
// Create scales
const xScale = d3.scaleBand()
.domain(data.map(d => d.label))
.range([0, innerWidth])
.padding(0.1);
const yScale = d3.scaleLinear()
.domain([0, d3.max(data, d => d.value)])
.range([innerHeight, 0])
.nice();
// Create and append axes
const xAxis = d3.axisBottom(xScale);
const yAxis = d3.axisLeft(yScale);
g.append("g")
.attr("class", "x-axis")
.attr("transform", `translate(0,${innerHeight})`)
.call(xAxis);
g.append("g")
.attr("class", "y-axis")
.call(yAxis);
// Bind data and create visual elements (bars in this example)
g.selectAll("rect")
.data(data)
.join("rect")
.attr("x", d => xScale(d.label))
.attr("y", d => yScale(d.value))
.attr("width", xScale.bandwidth())
.attr("height", d => innerHeight - yScale(d.value))
.attr("fill", "steelblue");
// Optional: Add axis labels
g.append("text")
.attr("class", "axis-label")
.attr("x", innerWidth / 2)
.attr("y", innerHeight + margin.bottom - 5)
.attr("text-anchor", "middle")
.text("Category");
g.append("text")
.attr("class", "axis-label")
.attr("transform", "rotate(-90)")
.attr("x", -innerHeight / 2)
.attr("y", -margin.left + 15)
.attr("text-anchor", "middle")
.text("Value");
}, [data]);
return (
<div className="chart-container">
<svg
ref={svgRef}
width="800"
height="400"
style={{ border: '1px solid #ddd' }}
/>
</div>
);
}
// Example usage
export default function App() {
const sampleData = [
{ label: 'A', value: 30 },
{ label: 'B', value: 80 },
{ label: 'C', value: 45 },
{ label: 'D', value: 60 },
{ label: 'E', value: 20 },
{ label: 'F', value: 90 }
];
return (
<div className="p-8">
<h1 className="text-2xl font-bold mb-4">Basic D3.js Chart</h1>
<BasicChart data={sampleData} />
</div>
);
}
@@ -1,227 +0,0 @@
import { useEffect, useRef, useState } from 'react';
import * as d3 from 'd3';
function InteractiveChart({ data }) {
const svgRef = useRef();
const tooltipRef = useRef();
const [selectedPoint, setSelectedPoint] = useState(null);
useEffect(() => {
if (!data || data.length === 0) return;
const svg = d3.select(svgRef.current);
svg.selectAll("*").remove();
// Dimensions
const width = 800;
const height = 500;
const margin = { top: 20, right: 30, bottom: 40, left: 50 };
const innerWidth = width - margin.left - margin.right;
const innerHeight = height - margin.top - margin.bottom;
// Create main group
const g = svg.append("g")
.attr("transform", `translate(${margin.left},${margin.top})`);
// Scales
const xScale = d3.scaleLinear()
.domain([0, d3.max(data, d => d.x)])
.range([0, innerWidth])
.nice();
const yScale = d3.scaleLinear()
.domain([0, d3.max(data, d => d.y)])
.range([innerHeight, 0])
.nice();
const sizeScale = d3.scaleSqrt()
.domain([0, d3.max(data, d => d.size || 10)])
.range([3, 20]);
const colourScale = d3.scaleOrdinal(d3.schemeCategory10);
// Add zoom behaviour
const zoom = d3.zoom()
.scaleExtent([0.5, 10])
.on("zoom", (event) => {
g.attr("transform", `translate(${margin.left + event.transform.x},${margin.top + event.transform.y}) scale(${event.transform.k})`);
});
svg.call(zoom);
// Axes
const xAxis = d3.axisBottom(xScale);
const yAxis = d3.axisLeft(yScale);
const xAxisGroup = g.append("g")
.attr("class", "x-axis")
.attr("transform", `translate(0,${innerHeight})`)
.call(xAxis);
const yAxisGroup = g.append("g")
.attr("class", "y-axis")
.call(yAxis);
// Grid lines
g.append("g")
.attr("class", "grid")
.attr("opacity", 0.1)
.call(d3.axisLeft(yScale)
.tickSize(-innerWidth)
.tickFormat(""));
g.append("g")
.attr("class", "grid")
.attr("opacity", 0.1)
.attr("transform", `translate(0,${innerHeight})`)
.call(d3.axisBottom(xScale)
.tickSize(-innerHeight)
.tickFormat(""));
// Tooltip
const tooltip = d3.select(tooltipRef.current);
// Data points
const circles = g.selectAll("circle")
.data(data)
.join("circle")
.attr("cx", d => xScale(d.x))
.attr("cy", d => yScale(d.y))
.attr("r", d => sizeScale(d.size || 10))
.attr("fill", d => colourScale(d.category || 'default'))
.attr("stroke", "#fff")
.attr("stroke-width", 2)
.attr("opacity", 0.7)
.style("cursor", "pointer");
// Hover interactions
circles
.on("mouseover", function(event, d) {
// Enlarge circle
d3.select(this)
.transition()
.duration(200)
.attr("opacity", 1)
.attr("stroke-width", 3);
// Show tooltip
tooltip
.style("display", "block")
.style("left", (event.pageX + 10) + "px")
.style("top", (event.pageY - 10) + "px")
.html(`
<strong>${d.label || 'Point'}</strong><br/>
X: ${d.x.toFixed(2)}<br/>
Y: ${d.y.toFixed(2)}<br/>
${d.category ? `Category: ${d.category}<br/>` : ''}
${d.size ? `Size: ${d.size.toFixed(2)}` : ''}
`);
})
.on("mousemove", function(event) {
tooltip
.style("left", (event.pageX + 10) + "px")
.style("top", (event.pageY - 10) + "px");
})
.on("mouseout", function() {
// Restore circle
d3.select(this)
.transition()
.duration(200)
.attr("opacity", 0.7)
.attr("stroke-width", 2);
// Hide tooltip
tooltip.style("display", "none");
})
.on("click", function(event, d) {
// Highlight selected point
circles.attr("stroke", "#fff").attr("stroke-width", 2);
d3.select(this)
.attr("stroke", "#000")
.attr("stroke-width", 3);
setSelectedPoint(d);
});
// Add transition on initial render
circles
.attr("r", 0)
.transition()
.duration(800)
.delay((d, i) => i * 20)
.attr("r", d => sizeScale(d.size || 10));
// Axis labels
g.append("text")
.attr("class", "axis-label")
.attr("x", innerWidth / 2)
.attr("y", innerHeight + margin.bottom - 5)
.attr("text-anchor", "middle")
.style("font-size", "14px")
.text("X Axis");
g.append("text")
.attr("class", "axis-label")
.attr("transform", "rotate(-90)")
.attr("x", -innerHeight / 2)
.attr("y", -margin.left + 15)
.attr("text-anchor", "middle")
.style("font-size", "14px")
.text("Y Axis");
}, [data]);
return (
<div className="relative">
<svg
ref={svgRef}
width="800"
height="500"
style={{ border: '1px solid #ddd', cursor: 'grab' }}
/>
<div
ref={tooltipRef}
style={{
position: 'absolute',
display: 'none',
padding: '10px',
background: 'white',
border: '1px solid #ddd',
borderRadius: '4px',
pointerEvents: 'none',
boxShadow: '0 2px 4px rgba(0,0,0,0.1)',
fontSize: '13px',
zIndex: 1000
}}
/>
{selectedPoint && (
<div className="mt-4 p-4 bg-blue-50 rounded border border-blue-200">
<h3 className="font-bold mb-2">Selected Point</h3>
<pre className="text-sm">{JSON.stringify(selectedPoint, null, 2)}</pre>
</div>
)}
</div>
);
}
// Example usage
export default function App() {
const sampleData = Array.from({ length: 50 }, (_, i) => ({
id: i,
label: `Point ${i + 1}`,
x: Math.random() * 100,
y: Math.random() * 100,
size: Math.random() * 30 + 5,
category: ['A', 'B', 'C', 'D'][Math.floor(Math.random() * 4)]
}));
return (
<div className="p-8">
<h1 className="text-2xl font-bold mb-2">Interactive D3.js Chart</h1>
<p className="text-gray-600 mb-4">
Hover over points for details. Click to select. Scroll to zoom. Drag to pan.
</p>
<InteractiveChart data={sampleData} />
</div>
);
}
@@ -1,115 +0,0 @@
{
"timeSeries": [
{ "date": "2024-01-01", "value": 120, "category": "A" },
{ "date": "2024-02-01", "value": 135, "category": "A" },
{ "date": "2024-03-01", "value": 128, "category": "A" },
{ "date": "2024-04-01", "value": 145, "category": "A" },
{ "date": "2024-05-01", "value": 152, "category": "A" },
{ "date": "2024-06-01", "value": 168, "category": "A" },
{ "date": "2024-07-01", "value": 175, "category": "A" },
{ "date": "2024-08-01", "value": 182, "category": "A" },
{ "date": "2024-09-01", "value": 190, "category": "A" },
{ "date": "2024-10-01", "value": 185, "category": "A" },
{ "date": "2024-11-01", "value": 195, "category": "A" },
{ "date": "2024-12-01", "value": 210, "category": "A" }
],
"categorical": [
{ "label": "Product A", "value": 450, "category": "Electronics" },
{ "label": "Product B", "value": 320, "category": "Electronics" },
{ "label": "Product C", "value": 580, "category": "Clothing" },
{ "label": "Product D", "value": 290, "category": "Clothing" },
{ "label": "Product E", "value": 410, "category": "Food" },
{ "label": "Product F", "value": 370, "category": "Food" }
],
"scatterData": [
{ "x": 12, "y": 45, "size": 25, "category": "Group A", "label": "Point 1" },
{ "x": 25, "y": 62, "size": 35, "category": "Group A", "label": "Point 2" },
{ "x": 38, "y": 55, "size": 20, "category": "Group B", "label": "Point 3" },
{ "x": 45, "y": 78, "size": 40, "category": "Group B", "label": "Point 4" },
{ "x": 52, "y": 68, "size": 30, "category": "Group C", "label": "Point 5" },
{ "x": 65, "y": 85, "size": 45, "category": "Group C", "label": "Point 6" },
{ "x": 72, "y": 72, "size": 28, "category": "Group A", "label": "Point 7" },
{ "x": 85, "y": 92, "size": 50, "category": "Group B", "label": "Point 8" }
],
"hierarchical": {
"name": "Root",
"children": [
{
"name": "Category 1",
"children": [
{ "name": "Item 1.1", "value": 100 },
{ "name": "Item 1.2", "value": 150 },
{ "name": "Item 1.3", "value": 80 }
]
},
{
"name": "Category 2",
"children": [
{ "name": "Item 2.1", "value": 200 },
{ "name": "Item 2.2", "value": 120 },
{ "name": "Item 2.3", "value": 90 }
]
},
{
"name": "Category 3",
"children": [
{ "name": "Item 3.1", "value": 180 },
{ "name": "Item 3.2", "value": 140 }
]
}
]
},
"network": {
"nodes": [
{ "id": "A", "group": 1 },
{ "id": "B", "group": 1 },
{ "id": "C", "group": 1 },
{ "id": "D", "group": 2 },
{ "id": "E", "group": 2 },
{ "id": "F", "group": 3 },
{ "id": "G", "group": 3 },
{ "id": "H", "group": 3 }
],
"links": [
{ "source": "A", "target": "B", "value": 1 },
{ "source": "A", "target": "C", "value": 2 },
{ "source": "B", "target": "C", "value": 1 },
{ "source": "C", "target": "D", "value": 3 },
{ "source": "D", "target": "E", "value": 2 },
{ "source": "E", "target": "F", "value": 1 },
{ "source": "F", "target": "G", "value": 2 },
{ "source": "F", "target": "H", "value": 1 },
{ "source": "G", "target": "H", "value": 1 }
]
},
"stackedData": [
{ "group": "Q1", "seriesA": 30, "seriesB": 40, "seriesC": 25 },
{ "group": "Q2", "seriesA": 45, "seriesB": 35, "seriesC": 30 },
{ "group": "Q3", "seriesA": 40, "seriesB": 50, "seriesC": 35 },
{ "group": "Q4", "seriesA": 55, "seriesB": 45, "seriesC": 40 }
],
"geographicPoints": [
{ "city": "London", "latitude": 51.5074, "longitude": -0.1278, "value": 8900000 },
{ "city": "Paris", "latitude": 48.8566, "longitude": 2.3522, "value": 2140000 },
{ "city": "Berlin", "latitude": 52.5200, "longitude": 13.4050, "value": 3645000 },
{ "city": "Madrid", "latitude": 40.4168, "longitude": -3.7038, "value": 3223000 },
{ "city": "Rome", "latitude": 41.9028, "longitude": 12.4964, "value": 2873000 }
],
"divergingData": [
{ "category": "Item A", "value": -15 },
{ "category": "Item B", "value": 8 },
{ "category": "Item C", "value": -22 },
{ "category": "Item D", "value": 18 },
{ "category": "Item E", "value": -5 },
{ "category": "Item F", "value": 25 },
{ "category": "Item G", "value": -12 },
{ "category": "Item H", "value": 14 }
]
}
@@ -1,564 +0,0 @@
# D3.js Colour Schemes and Palette Recommendations
Comprehensive guide to colour selection in data visualisation with d3.js.
## Built-in categorical colour schemes
### Category10 (default)
```javascript
d3.schemeCategory10
// ['#1f77b4', '#ff7f0e', '#2ca02c', '#d62728', '#9467bd',
// '#8c564b', '#e377c2', '#7f7f7f', '#bcbd22', '#17becf']
```
**Characteristics:**
- 10 distinct colours
- Good colour-blind accessibility
- Default choice for most categorical data
- Balanced saturation and brightness
**Use cases:** General purpose categorical encoding, legend items, multiple data series
### Tableau10
```javascript
d3.schemeTableau10
```
**Characteristics:**
- 10 colours optimised for data visualisation
- Professional appearance
- Excellent distinguishability
**Use cases:** Business dashboards, professional reports, presentations
### Accent
```javascript
d3.schemeAccent
// 8 colours with high saturation
```
**Characteristics:**
- Bright, vibrant colours
- High contrast
- Modern aesthetic
**Use cases:** Highlighting important categories, modern web applications
### Dark2
```javascript
d3.schemeDark2
// 8 darker, muted colours
```
**Characteristics:**
- Subdued palette
- Professional appearance
- Good for dark backgrounds
**Use cases:** Dark mode visualisations, professional contexts
### Paired
```javascript
d3.schemePaired
// 12 colours in pairs of similar hues
```
**Characteristics:**
- Pairs of light and dark variants
- Useful for nested categories
- 12 distinct colours
**Use cases:** Grouped bar charts, hierarchical categories, before/after comparisons
### Pastel1 & Pastel2
```javascript
d3.schemePastel1 // 9 colours
d3.schemePastel2 // 8 colours
```
**Characteristics:**
- Soft, low-saturation colours
- Gentle appearance
- Good for large areas
**Use cases:** Background colours, subtle categorisation, calming visualisations
### Set1, Set2, Set3
```javascript
d3.schemeSet1 // 9 colours - vivid
d3.schemeSet2 // 8 colours - muted
d3.schemeSet3 // 12 colours - pastel
```
**Characteristics:**
- Set1: High saturation, maximum distinction
- Set2: Professional, balanced
- Set3: Subtle, many categories
**Use cases:** Varied based on visual hierarchy needs
## Sequential colour schemes
Sequential schemes map continuous data from low to high values using a single hue or gradient.
### Single-hue sequential
**Blues:**
```javascript
d3.interpolateBlues
d3.schemeBlues[9] // 9-step discrete version
```
**Other single-hue options:**
- `d3.interpolateGreens` / `d3.schemeGreens`
- `d3.interpolateOranges` / `d3.schemeOranges`
- `d3.interpolatePurples` / `d3.schemePurples`
- `d3.interpolateReds` / `d3.schemeReds`
- `d3.interpolateGreys` / `d3.schemeGreys`
**Use cases:**
- Simple heat maps
- Choropleth maps
- Density plots
- Single-metric visualisations
### Multi-hue sequential
**Viridis (recommended):**
```javascript
d3.interpolateViridis
```
**Characteristics:**
- Perceptually uniform
- Colour-blind friendly
- Print-safe
- No visual dead zones
- Monotonically increasing perceived lightness
**Other perceptually-uniform options:**
- `d3.interpolatePlasma` - Purple to yellow
- `d3.interpolateInferno` - Black to white through red/orange
- `d3.interpolateMagma` - Black to white through purple
- `d3.interpolateCividis` - Colour-blind optimised
**Colour-blind accessible:**
```javascript
d3.interpolateTurbo // Rainbow-like but perceptually uniform
d3.interpolateCool // Cyan to magenta
d3.interpolateWarm // Orange to yellow
```
**Use cases:**
- Scientific visualisation
- Medical imaging
- Any high-precision data visualisation
- Accessible visualisations
### Traditional sequential
**Yellow-Orange-Red:**
```javascript
d3.interpolateYlOrRd
d3.schemeYlOrRd[9]
```
**Yellow-Green-Blue:**
```javascript
d3.interpolateYlGnBu
d3.schemeYlGnBu[9]
```
**Other multi-hue:**
- `d3.interpolateBuGn` - Blue to green
- `d3.interpolateBuPu` - Blue to purple
- `d3.interpolateGnBu` - Green to blue
- `d3.interpolateOrRd` - Orange to red
- `d3.interpolatePuBu` - Purple to blue
- `d3.interpolatePuBuGn` - Purple to blue-green
- `d3.interpolatePuRd` - Purple to red
- `d3.interpolateRdPu` - Red to purple
- `d3.interpolateYlGn` - Yellow to green
- `d3.interpolateYlOrBr` - Yellow to orange-brown
**Use cases:** Traditional data visualisation, familiar colour associations (temperature, vegetation, water)
## Diverging colour schemes
Diverging schemes highlight deviations from a central value using two distinct hues.
### Red-Blue (temperature)
```javascript
d3.interpolateRdBu
d3.schemeRdBu[11]
```
**Characteristics:**
- Intuitive temperature metaphor
- Strong contrast
- Clear positive/negative distinction
**Use cases:** Temperature, profit/loss, above/below average, correlation
### Red-Yellow-Blue
```javascript
d3.interpolateRdYlBu
d3.schemeRdYlBu[11]
```
**Characteristics:**
- Three-colour gradient
- Softer transition through yellow
- More visual steps
**Use cases:** When extreme values need emphasis and middle needs visibility
### Other diverging schemes
**Traffic light:**
```javascript
d3.interpolateRdYlGn // Red (bad) to green (good)
```
**Spectral (rainbow):**
```javascript
d3.interpolateSpectral // Full spectrum
```
**Other options:**
- `d3.interpolateBrBG` - Brown to blue-green
- `d3.interpolatePiYG` - Pink to yellow-green
- `d3.interpolatePRGn` - Purple to green
- `d3.interpolatePuOr` - Purple to orange
- `d3.interpolateRdGy` - Red to grey
**Use cases:** Choose based on semantic meaning and accessibility needs
## Colour-blind friendly palettes
### General guidelines
1. **Avoid red-green combinations** (most common colour blindness)
2. **Use blue-orange diverging** instead of red-green
3. **Add texture or patterns** as redundant encoding
4. **Test with simulation tools**
### Recommended colour-blind safe schemes
**Categorical:**
```javascript
// Okabe-Ito palette (colour-blind safe)
const okabePalette = [
'#E69F00', // Orange
'#56B4E9', // Sky blue
'#009E73', // Bluish green
'#F0E442', // Yellow
'#0072B2', // Blue
'#D55E00', // Vermillion
'#CC79A7', // Reddish purple
'#000000' // Black
];
const colourScale = d3.scaleOrdinal()
.domain(categories)
.range(okabePalette);
```
**Sequential:**
```javascript
// Use Viridis, Cividis, or Blues
d3.interpolateViridis // Best overall
d3.interpolateCividis // Optimised for CVD
d3.interpolateBlues // Simple, safe
```
**Diverging:**
```javascript
// Use blue-orange instead of red-green
d3.interpolateBrBG
d3.interpolatePuOr
```
## Custom colour palettes
### Creating custom sequential
```javascript
const customSequential = d3.scaleLinear()
.domain([0, 100])
.range(['#e8f4f8', '#006d9c']) // Light to dark blue
.interpolate(d3.interpolateLab); // Perceptually uniform
```
### Creating custom diverging
```javascript
const customDiverging = d3.scaleLinear()
.domain([0, 50, 100])
.range(['#ca0020', '#f7f7f7', '#0571b0']) // Red, grey, blue
.interpolate(d3.interpolateLab);
```
### Creating custom categorical
```javascript
// Brand colours
const brandPalette = [
'#FF6B6B', // Primary red
'#4ECDC4', // Secondary teal
'#45B7D1', // Tertiary blue
'#FFA07A', // Accent coral
'#98D8C8' // Accent mint
];
const colourScale = d3.scaleOrdinal()
.domain(categories)
.range(brandPalette);
```
## Semantic colour associations
### Universal colour meanings
**Red:**
- Danger, error, negative
- High temperature
- Debt, loss
**Green:**
- Success, positive
- Growth, vegetation
- Profit, gain
**Blue:**
- Trust, calm
- Water, cold
- Information, neutral
**Yellow/Orange:**
- Warning, caution
- Energy, warmth
- Attention
**Grey:**
- Neutral, inactive
- Missing data
- Background
### Context-specific palettes
**Financial:**
```javascript
const financialColours = {
profit: '#27ae60',
loss: '#e74c3c',
neutral: '#95a5a6',
highlight: '#3498db'
};
```
**Temperature:**
```javascript
const temperatureScale = d3.scaleSequential(d3.interpolateRdYlBu)
.domain([40, -10]); // Hot to cold (reversed)
```
**Traffic/Status:**
```javascript
const statusColours = {
success: '#27ae60',
warning: '#f39c12',
error: '#e74c3c',
info: '#3498db',
neutral: '#95a5a6'
};
```
## Accessibility best practices
### Contrast ratios
Ensure sufficient contrast between colours and backgrounds:
```javascript
// Good contrast example
const highContrast = {
background: '#ffffff',
text: '#2c3e50',
primary: '#3498db',
secondary: '#e74c3c'
};
```
**WCAG guidelines:**
- Normal text: 4.5:1 minimum
- Large text: 3:1 minimum
- UI components: 3:1 minimum
### Redundant encoding
Never rely solely on colour to convey information:
```javascript
// Add patterns or shapes
const symbols = ['circle', 'square', 'triangle', 'diamond'];
// Add text labels
// Use line styles (solid, dashed, dotted)
// Use size encoding
```
### Testing
Test visualisations for colour blindness:
- Chrome DevTools (Rendering > Emulate vision deficiencies)
- Colour Oracle (free desktop application)
- Coblis (online simulator)
## Professional colour recommendations
### Data journalism
```javascript
// Guardian style
const guardianPalette = [
'#005689', // Guardian blue
'#c70000', // Guardian red
'#7d0068', // Guardian pink
'#951c75', // Guardian purple
];
// FT style
const ftPalette = [
'#0f5499', // FT blue
'#990f3d', // FT red
'#593380', // FT purple
'#262a33', // FT black
];
```
### Academic/Scientific
```javascript
// Nature journal style
const naturePalette = [
'#0071b2', // Blue
'#d55e00', // Vermillion
'#009e73', // Green
'#f0e442', // Yellow
];
// Use Viridis for continuous data
const scientificScale = d3.scaleSequential(d3.interpolateViridis);
```
### Corporate/Business
```javascript
// Professional, conservative
const corporatePalette = [
'#003f5c', // Dark blue
'#58508d', // Purple
'#bc5090', // Magenta
'#ff6361', // Coral
'#ffa600' // Orange
];
```
## Dynamic colour selection
### Based on data range
```javascript
function selectColourScheme(data) {
const extent = d3.extent(data);
const hasNegative = extent[0] < 0;
const hasPositive = extent[1] > 0;
if (hasNegative && hasPositive) {
// Diverging: data crosses zero
return d3.scaleSequentialSymlog(d3.interpolateRdBu)
.domain([extent[0], 0, extent[1]]);
} else {
// Sequential: all positive or all negative
return d3.scaleSequential(d3.interpolateViridis)
.domain(extent);
}
}
```
### Based on category count
```javascript
function selectCategoricalScheme(categories) {
const n = categories.length;
if (n <= 10) {
return d3.scaleOrdinal(d3.schemeTableau10);
} else if (n <= 12) {
return d3.scaleOrdinal(d3.schemePaired);
} else {
// For many categories, use sequential with quantize
return d3.scaleQuantize()
.domain([0, n - 1])
.range(d3.quantize(d3.interpolateRainbow, n));
}
}
```
## Common colour mistakes to avoid
1. **Rainbow gradients for sequential data**
- Problem: Not perceptually uniform, hard to read
- Solution: Use Viridis, Blues, or other uniform schemes
2. **Red-green for diverging (colour blindness)**
- Problem: 8% of males can't distinguish
- Solution: Use blue-orange or purple-green
3. **Too many categorical colours**
- Problem: Hard to distinguish and remember
- Solution: Limit to 5-8 categories, use grouping
4. **Insufficient contrast**
- Problem: Poor readability
- Solution: Test contrast ratios, use darker colours on light backgrounds
5. **Culturally inconsistent colours**
- Problem: Confusing semantic meaning
- Solution: Research colour associations for target audience
6. **Inverted temperature scales**
- Problem: Counterintuitive (red = cold)
- Solution: Red/orange = hot, blue = cold
## Quick reference guide
**Need to show...**
- **Categories (≤10):** `d3.schemeCategory10` or `d3.schemeTableau10`
- **Categories (>10):** `d3.schemePaired` or group categories
- **Sequential (general):** `d3.interpolateViridis`
- **Sequential (scientific):** `d3.interpolateViridis` or `d3.interpolatePlasma`
- **Sequential (temperature):** `d3.interpolateRdYlBu` (inverted)
- **Diverging (zero):** `d3.interpolateRdBu` or `d3.interpolateBrBG`
- **Diverging (good/bad):** `d3.interpolateRdYlGn` (inverted)
- **Colour-blind safe (categorical):** Okabe-Ito palette (shown above)
- **Colour-blind safe (sequential):** `d3.interpolateCividis` or `d3.interpolateBlues`
- **Colour-blind safe (diverging):** `d3.interpolatePuOr` or `d3.interpolateBrBG`
**Always remember:**
1. Test for colour-blindness
2. Ensure sufficient contrast
3. Use semantic colours appropriately
4. Add redundant encoding (patterns, labels)
5. Keep it simple (fewer colours = clearer visualisation)
@@ -1,869 +0,0 @@
# D3.js Visualisation Patterns
This reference provides detailed code patterns for common d3.js visualisation types.
## Hierarchical visualisations
### Tree diagram
```javascript
useEffect(() => {
if (!data) return;
const svg = d3.select(svgRef.current);
svg.selectAll("*").remove();
const width = 800;
const height = 600;
const tree = d3.tree().size([height - 100, width - 200]);
const root = d3.hierarchy(data);
tree(root);
const g = svg.append("g")
.attr("transform", "translate(100,50)");
// Links
g.selectAll("path")
.data(root.links())
.join("path")
.attr("d", d3.linkHorizontal()
.x(d => d.y)
.y(d => d.x))
.attr("fill", "none")
.attr("stroke", "#555")
.attr("stroke-width", 2);
// Nodes
const node = g.selectAll("g")
.data(root.descendants())
.join("g")
.attr("transform", d => `translate(${d.y},${d.x})`);
node.append("circle")
.attr("r", 6)
.attr("fill", d => d.children ? "#555" : "#999");
node.append("text")
.attr("dy", "0.31em")
.attr("x", d => d.children ? -8 : 8)
.attr("text-anchor", d => d.children ? "end" : "start")
.text(d => d.data.name)
.style("font-size", "12px");
}, [data]);
```
### Treemap
```javascript
useEffect(() => {
if (!data) return;
const svg = d3.select(svgRef.current);
svg.selectAll("*").remove();
const width = 800;
const height = 600;
const root = d3.hierarchy(data)
.sum(d => d.value)
.sort((a, b) => b.value - a.value);
d3.treemap()
.size([width, height])
.padding(2)
.round(true)(root);
const colourScale = d3.scaleOrdinal(d3.schemeCategory10);
const cell = svg.selectAll("g")
.data(root.leaves())
.join("g")
.attr("transform", d => `translate(${d.x0},${d.y0})`);
cell.append("rect")
.attr("width", d => d.x1 - d.x0)
.attr("height", d => d.y1 - d.y0)
.attr("fill", d => colourScale(d.parent.data.name))
.attr("stroke", "white")
.attr("stroke-width", 2);
cell.append("text")
.attr("x", 4)
.attr("y", 16)
.text(d => d.data.name)
.style("font-size", "12px")
.style("fill", "white");
}, [data]);
```
### Sunburst diagram
```javascript
useEffect(() => {
if (!data) return;
const svg = d3.select(svgRef.current);
svg.selectAll("*").remove();
const width = 600;
const height = 600;
const radius = Math.min(width, height) / 2;
const root = d3.hierarchy(data)
.sum(d => d.value)
.sort((a, b) => b.value - a.value);
const partition = d3.partition()
.size([2 * Math.PI, radius]);
partition(root);
const arc = d3.arc()
.startAngle(d => d.x0)
.endAngle(d => d.x1)
.innerRadius(d => d.y0)
.outerRadius(d => d.y1);
const colourScale = d3.scaleOrdinal(d3.schemeCategory10);
const g = svg.append("g")
.attr("transform", `translate(${width / 2},${height / 2})`);
g.selectAll("path")
.data(root.descendants())
.join("path")
.attr("d", arc)
.attr("fill", d => colourScale(d.depth))
.attr("stroke", "white")
.attr("stroke-width", 1);
}, [data]);
```
### Chord diagram
```javascript
function drawChordDiagram(data) {
// data format: array of objects with source, target, and value
// Example: [{ source: 'A', target: 'B', value: 10 }, ...]
if (!data || data.length === 0) return;
const svg = d3.select('#chart');
svg.selectAll("*").remove();
const width = 600;
const height = 600;
const innerRadius = Math.min(width, height) * 0.3;
const outerRadius = innerRadius + 30;
// Create matrix from data
const nodes = Array.from(new Set(data.flatMap(d => [d.source, d.target])));
const matrix = Array.from({ length: nodes.length }, () => Array(nodes.length).fill(0));
data.forEach(d => {
const i = nodes.indexOf(d.source);
const j = nodes.indexOf(d.target);
matrix[i][j] += d.value;
matrix[j][i] += d.value;
});
// Create chord layout
const chord = d3.chord()
.padAngle(0.05)
.sortSubgroups(d3.descending);
const arc = d3.arc()
.innerRadius(innerRadius)
.outerRadius(outerRadius);
const ribbon = d3.ribbon()
.source(d => d.source)
.target(d => d.target);
const colourScale = d3.scaleOrdinal(d3.schemeCategory10)
.domain(nodes);
const g = svg.append("g")
.attr("transform", `translate(${width / 2},${height / 2})`);
const chords = chord(matrix);
// Draw ribbons
g.append("g")
.attr("fill-opacity", 0.67)
.selectAll("path")
.data(chords)
.join("path")
.attr("d", ribbon)
.attr("fill", d => colourScale(nodes[d.source.index]))
.attr("stroke", d => d3.rgb(colourScale(nodes[d.source.index])).darker());
// Draw groups (arcs)
const group = g.append("g")
.selectAll("g")
.data(chords.groups)
.join("g");
group.append("path")
.attr("d", arc)
.attr("fill", d => colourScale(nodes[d.index]))
.attr("stroke", d => d3.rgb(colourScale(nodes[d.index])).darker());
// Add labels
group.append("text")
.each(d => { d.angle = (d.startAngle + d.endAngle) / 2; })
.attr("dy", "0.31em")
.attr("transform", d => `rotate(${(d.angle * 180 / Math.PI) - 90})translate(${outerRadius + 30})${d.angle > Math.PI ? "rotate(180)" : ""}`)
.attr("text-anchor", d => d.angle > Math.PI ? "end" : null)
.text((d, i) => nodes[i])
.style("font-size", "12px");
}
// Data format example:
// const data = [
// { source: 'Category A', target: 'Category B', value: 100 },
// { source: 'Category A', target: 'Category C', value: 50 },
// { source: 'Category B', target: 'Category C', value: 75 }
// ];
// drawChordDiagram(data);
```
## Advanced chart types
### Heatmap
```javascript
function drawHeatmap(data) {
// data format: array of objects with row, column, and value
// Example: [{ row: 'A', column: 'X', value: 10 }, ...]
if (!data || data.length === 0) return;
const svg = d3.select('#chart');
svg.selectAll("*").remove();
const width = 800;
const height = 600;
const margin = { top: 100, right: 30, bottom: 30, left: 100 };
const innerWidth = width - margin.left - margin.right;
const innerHeight = height - margin.top - margin.bottom;
// Get unique rows and columns
const rows = Array.from(new Set(data.map(d => d.row)));
const columns = Array.from(new Set(data.map(d => d.column)));
const g = svg.append("g")
.attr("transform", `translate(${margin.left},${margin.top})`);
// Create scales
const xScale = d3.scaleBand()
.domain(columns)
.range([0, innerWidth])
.padding(0.01);
const yScale = d3.scaleBand()
.domain(rows)
.range([0, innerHeight])
.padding(0.01);
// Colour scale for values (sequential from light to dark red)
const colourScale = d3.scaleSequential(d3.interpolateYlOrRd)
.domain([0, d3.max(data, d => d.value)]);
// Draw rectangles
g.selectAll("rect")
.data(data)
.join("rect")
.attr("x", d => xScale(d.column))
.attr("y", d => yScale(d.row))
.attr("width", xScale.bandwidth())
.attr("height", yScale.bandwidth())
.attr("fill", d => colourScale(d.value));
// Add x-axis labels
svg.append("g")
.attr("transform", `translate(${margin.left},${margin.top})`)
.selectAll("text")
.data(columns)
.join("text")
.attr("x", d => xScale(d) + xScale.bandwidth() / 2)
.attr("y", -10)
.attr("text-anchor", "middle")
.text(d => d)
.style("font-size", "12px");
// Add y-axis labels
svg.append("g")
.attr("transform", `translate(${margin.left},${margin.top})`)
.selectAll("text")
.data(rows)
.join("text")
.attr("x", -10)
.attr("y", d => yScale(d) + yScale.bandwidth() / 2)
.attr("dy", "0.35em")
.attr("text-anchor", "end")
.text(d => d)
.style("font-size", "12px");
// Add colour legend
const legendWidth = 20;
const legendHeight = 200;
const legend = svg.append("g")
.attr("transform", `translate(${width - 60},${margin.top})`);
const legendScale = d3.scaleLinear()
.domain(colourScale.domain())
.range([legendHeight, 0]);
const legendAxis = d3.axisRight(legendScale).ticks(5);
// Draw colour gradient in legend
for (let i = 0; i < legendHeight; i++) {
legend.append("rect")
.attr("y", i)
.attr("width", legendWidth)
.attr("height", 1)
.attr("fill", colourScale(legendScale.invert(i)));
}
legend.append("g")
.attr("transform", `translate(${legendWidth},0)`)
.call(legendAxis);
}
// Data format example:
// const data = [
// { row: 'Monday', column: 'Morning', value: 42 },
// { row: 'Monday', column: 'Afternoon', value: 78 },
// { row: 'Tuesday', column: 'Morning', value: 65 },
// { row: 'Tuesday', column: 'Afternoon', value: 55 }
// ];
// drawHeatmap(data);
```
### Area chart with gradient
```javascript
useEffect(() => {
if (!data || data.length === 0) return;
const svg = d3.select(svgRef.current);
svg.selectAll("*").remove();
const width = 800;
const height = 400;
const margin = { top: 20, right: 30, bottom: 40, left: 50 };
const innerWidth = width - margin.left - margin.right;
const innerHeight = height - margin.top - margin.bottom;
// Define gradient
const defs = svg.append("defs");
const gradient = defs.append("linearGradient")
.attr("id", "areaGradient")
.attr("x1", "0%")
.attr("x2", "0%")
.attr("y1", "0%")
.attr("y2", "100%");
gradient.append("stop")
.attr("offset", "0%")
.attr("stop-color", "steelblue")
.attr("stop-opacity", 0.8);
gradient.append("stop")
.attr("offset", "100%")
.attr("stop-color", "steelblue")
.attr("stop-opacity", 0.1);
const g = svg.append("g")
.attr("transform", `translate(${margin.left},${margin.top})`);
const xScale = d3.scaleTime()
.domain(d3.extent(data, d => d.date))
.range([0, innerWidth]);
const yScale = d3.scaleLinear()
.domain([0, d3.max(data, d => d.value)])
.range([innerHeight, 0]);
const area = d3.area()
.x(d => xScale(d.date))
.y0(innerHeight)
.y1(d => yScale(d.value))
.curve(d3.curveMonotoneX);
g.append("path")
.datum(data)
.attr("fill", "url(#areaGradient)")
.attr("d", area);
const line = d3.line()
.x(d => xScale(d.date))
.y(d => yScale(d.value))
.curve(d3.curveMonotoneX);
g.append("path")
.datum(data)
.attr("fill", "none")
.attr("stroke", "steelblue")
.attr("stroke-width", 2)
.attr("d", line);
g.append("g")
.attr("transform", `translate(0,${innerHeight})`)
.call(d3.axisBottom(xScale));
g.append("g")
.call(d3.axisLeft(yScale));
}, [data]);
```
### Stacked bar chart
```javascript
useEffect(() => {
if (!data || data.length === 0) return;
const svg = d3.select(svgRef.current);
svg.selectAll("*").remove();
const width = 800;
const height = 400;
const margin = { top: 20, right: 30, bottom: 40, left: 50 };
const innerWidth = width - margin.left - margin.right;
const innerHeight = height - margin.top - margin.bottom;
const g = svg.append("g")
.attr("transform", `translate(${margin.left},${margin.top})`);
const categories = Object.keys(data[0]).filter(k => k !== 'group');
const stackedData = d3.stack().keys(categories)(data);
const xScale = d3.scaleBand()
.domain(data.map(d => d.group))
.range([0, innerWidth])
.padding(0.1);
const yScale = d3.scaleLinear()
.domain([0, d3.max(stackedData[stackedData.length - 1], d => d[1])])
.range([innerHeight, 0]);
const colourScale = d3.scaleOrdinal(d3.schemeCategory10);
g.selectAll("g")
.data(stackedData)
.join("g")
.attr("fill", (d, i) => colourScale(i))
.selectAll("rect")
.data(d => d)
.join("rect")
.attr("x", d => xScale(d.data.group))
.attr("y", d => yScale(d[1]))
.attr("height", d => yScale(d[0]) - yScale(d[1]))
.attr("width", xScale.bandwidth());
g.append("g")
.attr("transform", `translate(0,${innerHeight})`)
.call(d3.axisBottom(xScale));
g.append("g")
.call(d3.axisLeft(yScale));
}, [data]);
```
### Grouped bar chart
```javascript
useEffect(() => {
if (!data || data.length === 0) return;
const svg = d3.select(svgRef.current);
svg.selectAll("*").remove();
const width = 800;
const height = 400;
const margin = { top: 20, right: 30, bottom: 40, left: 50 };
const innerWidth = width - margin.left - margin.right;
const innerHeight = height - margin.top - margin.bottom;
const g = svg.append("g")
.attr("transform", `translate(${margin.left},${margin.top})`);
const categories = Object.keys(data[0]).filter(k => k !== 'group');
const x0Scale = d3.scaleBand()
.domain(data.map(d => d.group))
.range([0, innerWidth])
.padding(0.1);
const x1Scale = d3.scaleBand()
.domain(categories)
.range([0, x0Scale.bandwidth()])
.padding(0.05);
const yScale = d3.scaleLinear()
.domain([0, d3.max(data, d => Math.max(...categories.map(c => d[c])))])
.range([innerHeight, 0]);
const colourScale = d3.scaleOrdinal(d3.schemeCategory10);
const group = g.selectAll("g")
.data(data)
.join("g")
.attr("transform", d => `translate(${x0Scale(d.group)},0)`);
group.selectAll("rect")
.data(d => categories.map(key => ({ key, value: d[key] })))
.join("rect")
.attr("x", d => x1Scale(d.key))
.attr("y", d => yScale(d.value))
.attr("width", x1Scale.bandwidth())
.attr("height", d => innerHeight - yScale(d.value))
.attr("fill", d => colourScale(d.key));
g.append("g")
.attr("transform", `translate(0,${innerHeight})`)
.call(d3.axisBottom(x0Scale));
g.append("g")
.call(d3.axisLeft(yScale));
}, [data]);
```
### Bubble chart
```javascript
useEffect(() => {
if (!data || data.length === 0) return;
const svg = d3.select(svgRef.current);
svg.selectAll("*").remove();
const width = 800;
const height = 600;
const margin = { top: 20, right: 30, bottom: 40, left: 50 };
const innerWidth = width - margin.left - margin.right;
const innerHeight = height - margin.top - margin.bottom;
const g = svg.append("g")
.attr("transform", `translate(${margin.left},${margin.top})`);
const xScale = d3.scaleLinear()
.domain([0, d3.max(data, d => d.x)])
.range([0, innerWidth]);
const yScale = d3.scaleLinear()
.domain([0, d3.max(data, d => d.y)])
.range([innerHeight, 0]);
const sizeScale = d3.scaleSqrt()
.domain([0, d3.max(data, d => d.size)])
.range([0, 50]);
const colourScale = d3.scaleOrdinal(d3.schemeCategory10);
g.selectAll("circle")
.data(data)
.join("circle")
.attr("cx", d => xScale(d.x))
.attr("cy", d => yScale(d.y))
.attr("r", d => sizeScale(d.size))
.attr("fill", d => colourScale(d.category))
.attr("opacity", 0.6)
.attr("stroke", "white")
.attr("stroke-width", 2);
g.append("g")
.attr("transform", `translate(0,${innerHeight})`)
.call(d3.axisBottom(xScale));
g.append("g")
.call(d3.axisLeft(yScale));
}, [data]);
```
## Geographic visualisations
### Basic map with points
```javascript
useEffect(() => {
if (!geoData || !pointData) return;
const svg = d3.select(svgRef.current);
svg.selectAll("*").remove();
const width = 800;
const height = 600;
const projection = d3.geoMercator()
.fitSize([width, height], geoData);
const pathGenerator = d3.geoPath().projection(projection);
// Draw map
svg.selectAll("path")
.data(geoData.features)
.join("path")
.attr("d", pathGenerator)
.attr("fill", "#e0e0e0")
.attr("stroke", "#999")
.attr("stroke-width", 0.5);
// Draw points
svg.selectAll("circle")
.data(pointData)
.join("circle")
.attr("cx", d => projection([d.longitude, d.latitude])[0])
.attr("cy", d => projection([d.longitude, d.latitude])[1])
.attr("r", 5)
.attr("fill", "steelblue")
.attr("opacity", 0.7);
}, [geoData, pointData]);
```
### Choropleth map
```javascript
useEffect(() => {
if (!geoData || !valueData) return;
const svg = d3.select(svgRef.current);
svg.selectAll("*").remove();
const width = 800;
const height = 600;
const projection = d3.geoMercator()
.fitSize([width, height], geoData);
const pathGenerator = d3.geoPath().projection(projection);
// Create value lookup
const valueLookup = new Map(valueData.map(d => [d.id, d.value]));
// Colour scale
const colourScale = d3.scaleSequential(d3.interpolateBlues)
.domain([0, d3.max(valueData, d => d.value)]);
svg.selectAll("path")
.data(geoData.features)
.join("path")
.attr("d", pathGenerator)
.attr("fill", d => {
const value = valueLookup.get(d.id);
return value ? colourScale(value) : "#e0e0e0";
})
.attr("stroke", "#999")
.attr("stroke-width", 0.5);
}, [geoData, valueData]);
```
## Advanced interactions
### Brush and zoom
```javascript
useEffect(() => {
if (!data || data.length === 0) return;
const svg = d3.select(svgRef.current);
svg.selectAll("*").remove();
const width = 800;
const height = 400;
const margin = { top: 20, right: 30, bottom: 40, left: 50 };
const innerWidth = width - margin.left - margin.right;
const innerHeight = height - margin.top - margin.bottom;
const xScale = d3.scaleLinear()
.domain([0, d3.max(data, d => d.x)])
.range([0, innerWidth]);
const yScale = d3.scaleLinear()
.domain([0, d3.max(data, d => d.y)])
.range([innerHeight, 0]);
const g = svg.append("g")
.attr("transform", `translate(${margin.left},${margin.top})`);
const circles = g.selectAll("circle")
.data(data)
.join("circle")
.attr("cx", d => xScale(d.x))
.attr("cy", d => yScale(d.y))
.attr("r", 5)
.attr("fill", "steelblue");
// Add brush
const brush = d3.brush()
.extent([[0, 0], [innerWidth, innerHeight]])
.on("start brush", (event) => {
if (!event.selection) return;
const [[x0, y0], [x1, y1]] = event.selection;
circles.attr("fill", d => {
const cx = xScale(d.x);
const cy = yScale(d.y);
return (cx >= x0 && cx <= x1 && cy >= y0 && cy <= y1)
? "orange"
: "steelblue";
});
});
g.append("g")
.attr("class", "brush")
.call(brush);
}, [data]);
```
### Linked brushing between charts
```javascript
function LinkedCharts({ data }) {
const [selectedPoints, setSelectedPoints] = useState(new Set());
const svg1Ref = useRef();
const svg2Ref = useRef();
useEffect(() => {
// Chart 1: Scatter plot
const svg1 = d3.select(svg1Ref.current);
svg1.selectAll("*").remove();
// ... create first chart ...
const circles1 = svg1.selectAll("circle")
.data(data)
.join("circle")
.attr("fill", d => selectedPoints.has(d.id) ? "orange" : "steelblue");
// Chart 2: Bar chart
const svg2 = d3.select(svg2Ref.current);
svg2.selectAll("*").remove();
// ... create second chart ...
const bars = svg2.selectAll("rect")
.data(data)
.join("rect")
.attr("fill", d => selectedPoints.has(d.id) ? "orange" : "steelblue");
// Add brush to first chart
const brush = d3.brush()
.on("start brush end", (event) => {
if (!event.selection) {
setSelectedPoints(new Set());
return;
}
const [[x0, y0], [x1, y1]] = event.selection;
const selected = new Set();
data.forEach(d => {
const x = xScale(d.x);
const y = yScale(d.y);
if (x >= x0 && x <= x1 && y >= y0 && y <= y1) {
selected.add(d.id);
}
});
setSelectedPoints(selected);
});
svg1.append("g").call(brush);
}, [data, selectedPoints]);
return (
<div>
<svg ref={svg1Ref} width="400" height="300" />
<svg ref={svg2Ref} width="400" height="300" />
</div>
);
}
```
## Animation patterns
### Enter, update, exit with transitions
```javascript
useEffect(() => {
if (!data || data.length === 0) return;
const svg = d3.select(svgRef.current);
const circles = svg.selectAll("circle")
.data(data, d => d.id); // Key function for object constancy
// EXIT: Remove old elements
circles.exit()
.transition()
.duration(500)
.attr("r", 0)
.remove();
// UPDATE: Modify existing elements
circles
.transition()
.duration(500)
.attr("cx", d => xScale(d.x))
.attr("cy", d => yScale(d.y))
.attr("fill", "steelblue");
// ENTER: Add new elements
circles.enter()
.append("circle")
.attr("cx", d => xScale(d.x))
.attr("cy", d => yScale(d.y))
.attr("r", 0)
.attr("fill", "steelblue")
.transition()
.duration(500)
.attr("r", 5);
}, [data]);
```
### Path morphing
```javascript
useEffect(() => {
if (!data1 || !data2) return;
const svg = d3.select(svgRef.current);
const line = d3.line()
.x(d => xScale(d.x))
.y(d => yScale(d.y))
.curve(d3.curveMonotoneX);
const path = svg.select("path");
// Morph from data1 to data2
path
.datum(data1)
.attr("d", line)
.transition()
.duration(1000)
.attrTween("d", function() {
const previous = d3.select(this).attr("d");
const current = line(data2);
return d3.interpolatePath(previous, current);
});
}, [data1, data2]);
```
@@ -1,509 +0,0 @@
# D3.js Scale Reference
Comprehensive guide to all d3 scale types with examples and use cases.
## Continuous scales
### Linear scale
Maps continuous input domain to continuous output range with linear interpolation.
```javascript
const scale = d3.scaleLinear()
.domain([0, 100])
.range([0, 500]);
scale(50); // Returns 250
scale(0); // Returns 0
scale(100); // Returns 500
// Invert scale (get input from output)
scale.invert(250); // Returns 50
```
**Use cases:**
- Most common scale for quantitative data
- Axes, bar lengths, position encoding
- Temperature, prices, counts, measurements
**Methods:**
- `.domain([min, max])` - Set input domain
- `.range([min, max])` - Set output range
- `.invert(value)` - Get domain value from range value
- `.clamp(true)` - Restrict output to range bounds
- `.nice()` - Extend domain to nice round values
### Power scale
Maps continuous input to continuous output with exponential transformation.
```javascript
const sqrtScale = d3.scalePow()
.exponent(0.5) // Square root
.domain([0, 100])
.range([0, 500]);
const squareScale = d3.scalePow()
.exponent(2) // Square
.domain([0, 100])
.range([0, 500]);
// Shorthand for square root
const sqrtScale2 = d3.scaleSqrt()
.domain([0, 100])
.range([0, 500]);
```
**Use cases:**
- Perceptual scaling (human perception is non-linear)
- Area encoding (use square root to map values to circle radii)
- Emphasising differences in small or large values
### Logarithmic scale
Maps continuous input to continuous output with logarithmic transformation.
```javascript
const logScale = d3.scaleLog()
.domain([1, 1000]) // Must be positive
.range([0, 500]);
logScale(1); // Returns 0
logScale(10); // Returns ~167
logScale(100); // Returns ~333
logScale(1000); // Returns 500
```
**Use cases:**
- Data spanning multiple orders of magnitude
- Population, GDP, wealth distributions
- Logarithmic axes
- Exponential growth visualisations
**Important:** Domain values must be strictly positive (>0).
### Time scale
Specialised linear scale for temporal data.
```javascript
const timeScale = d3.scaleTime()
.domain([new Date(2020, 0, 1), new Date(2024, 0, 1)])
.range([0, 800]);
timeScale(new Date(2022, 0, 1)); // Returns 400
// Invert to get date
timeScale.invert(400); // Returns Date object for mid-2022
```
**Use cases:**
- Time series visualisations
- Timeline axes
- Temporal animations
- Date-based interactions
**Methods:**
- `.nice()` - Extend domain to nice time intervals
- `.ticks(count)` - Generate nicely-spaced tick values
- All linear scale methods apply
### Quantize scale
Maps continuous input to discrete output buckets.
```javascript
const quantizeScale = d3.scaleQuantize()
.domain([0, 100])
.range(['low', 'medium', 'high']);
quantizeScale(25); // Returns 'low'
quantizeScale(50); // Returns 'medium'
quantizeScale(75); // Returns 'high'
// Get the threshold values
quantizeScale.thresholds(); // Returns [33.33, 66.67]
```
**Use cases:**
- Binning continuous data
- Heat map colours
- Risk categories (low/medium/high)
- Age groups, income brackets
### Quantile scale
Maps continuous input to discrete output based on quantiles.
```javascript
const quantileScale = d3.scaleQuantile()
.domain([3, 6, 7, 8, 8, 10, 13, 15, 16, 20, 24]) // Sample data
.range(['low', 'medium', 'high']);
quantileScale(8); // Returns based on quantile position
quantileScale.quantiles(); // Returns quantile thresholds
```
**Use cases:**
- Equal-size groups regardless of distribution
- Percentile-based categorisation
- Handling skewed distributions
### Threshold scale
Maps continuous input to discrete output with custom thresholds.
```javascript
const thresholdScale = d3.scaleThreshold()
.domain([0, 10, 20])
.range(['freezing', 'cold', 'warm', 'hot']);
thresholdScale(-5); // Returns 'freezing'
thresholdScale(5); // Returns 'cold'
thresholdScale(15); // Returns 'warm'
thresholdScale(25); // Returns 'hot'
```
**Use cases:**
- Custom breakpoints
- Grade boundaries (A, B, C, D, F)
- Temperature categories
- Air quality indices
## Sequential scales
### Sequential colour scale
Maps continuous input to continuous colour gradient.
```javascript
const colourScale = d3.scaleSequential(d3.interpolateBlues)
.domain([0, 100]);
colourScale(0); // Returns lightest blue
colourScale(50); // Returns mid blue
colourScale(100); // Returns darkest blue
```
**Available interpolators:**
**Single hue:**
- `d3.interpolateBlues`, `d3.interpolateGreens`, `d3.interpolateReds`
- `d3.interpolateOranges`, `d3.interpolatePurples`, `d3.interpolateGreys`
**Multi-hue:**
- `d3.interpolateViridis`, `d3.interpolateInferno`, `d3.interpolateMagma`
- `d3.interpolatePlasma`, `d3.interpolateWarm`, `d3.interpolateCool`
- `d3.interpolateCubehelixDefault`, `d3.interpolateTurbo`
**Use cases:**
- Heat maps, choropleth maps
- Continuous data visualisation
- Temperature, elevation, density
### Diverging colour scale
Maps continuous input to diverging colour gradient with a midpoint.
```javascript
const divergingScale = d3.scaleDiverging(d3.interpolateRdBu)
.domain([-10, 0, 10]);
divergingScale(-10); // Returns red
divergingScale(0); // Returns white/neutral
divergingScale(10); // Returns blue
```
**Available interpolators:**
- `d3.interpolateRdBu` - Red to blue
- `d3.interpolateRdYlBu` - Red, yellow, blue
- `d3.interpolateRdYlGn` - Red, yellow, green
- `d3.interpolatePiYG` - Pink, yellow, green
- `d3.interpolateBrBG` - Brown, blue-green
- `d3.interpolatePRGn` - Purple, green
- `d3.interpolatePuOr` - Purple, orange
- `d3.interpolateRdGy` - Red, grey
- `d3.interpolateSpectral` - Rainbow spectrum
**Use cases:**
- Data with meaningful midpoint (zero, average, neutral)
- Positive/negative values
- Above/below comparisons
- Correlation matrices
### Sequential quantile scale
Combines sequential colour with quantile mapping.
```javascript
const sequentialQuantileScale = d3.scaleSequentialQuantile(d3.interpolateBlues)
.domain([3, 6, 7, 8, 8, 10, 13, 15, 16, 20, 24]);
// Maps based on quantile position
```
**Use cases:**
- Perceptually uniform binning
- Handling outliers
- Skewed distributions
## Ordinal scales
### Band scale
Maps discrete input to continuous bands (rectangles) with optional padding.
```javascript
const bandScale = d3.scaleBand()
.domain(['A', 'B', 'C', 'D'])
.range([0, 400])
.padding(0.1);
bandScale('A'); // Returns start position (e.g., 0)
bandScale('B'); // Returns start position (e.g., 110)
bandScale.bandwidth(); // Returns width of each band (e.g., 95)
bandScale.step(); // Returns total step including padding
bandScale.paddingInner(); // Returns inner padding (between bands)
bandScale.paddingOuter(); // Returns outer padding (at edges)
```
**Use cases:**
- Bar charts (most common use case)
- Grouped elements
- Categorical axes
- Heat map cells
**Padding options:**
- `.padding(value)` - Sets both inner and outer padding (0-1)
- `.paddingInner(value)` - Padding between bands (0-1)
- `.paddingOuter(value)` - Padding at edges (0-1)
- `.align(value)` - Alignment of bands (0-1, default 0.5)
### Point scale
Maps discrete input to continuous points (no width).
```javascript
const pointScale = d3.scalePoint()
.domain(['A', 'B', 'C', 'D'])
.range([0, 400])
.padding(0.5);
pointScale('A'); // Returns position (e.g., 50)
pointScale('B'); // Returns position (e.g., 150)
pointScale('C'); // Returns position (e.g., 250)
pointScale('D'); // Returns position (e.g., 350)
pointScale.step(); // Returns distance between points
```
**Use cases:**
- Line chart categorical x-axis
- Scatter plot with categorical axis
- Node positions in network graphs
- Any point positioning for categories
### Ordinal colour scale
Maps discrete input to discrete output (colours, shapes, etc.).
```javascript
const colourScale = d3.scaleOrdinal(d3.schemeCategory10);
colourScale('apples'); // Returns first colour
colourScale('oranges'); // Returns second colour
colourScale('apples'); // Returns same first colour (consistent)
// Custom range
const customScale = d3.scaleOrdinal()
.domain(['cat1', 'cat2', 'cat3'])
.range(['#FF6B6B', '#4ECDC4', '#45B7D1']);
```
**Built-in colour schemes:**
**Categorical:**
- `d3.schemeCategory10` - 10 colours
- `d3.schemeAccent` - 8 colours
- `d3.schemeDark2` - 8 colours
- `d3.schemePaired` - 12 colours
- `d3.schemePastel1` - 9 colours
- `d3.schemePastel2` - 8 colours
- `d3.schemeSet1` - 9 colours
- `d3.schemeSet2` - 8 colours
- `d3.schemeSet3` - 12 colours
- `d3.schemeTableau10` - 10 colours
**Use cases:**
- Category colours
- Legend items
- Multi-series charts
- Network node types
## Scale utilities
### Nice domain
Extend domain to nice round values.
```javascript
const scale = d3.scaleLinear()
.domain([0.201, 0.996])
.nice();
scale.domain(); // Returns [0.2, 1.0]
// With count (approximate tick count)
const scale2 = d3.scaleLinear()
.domain([0.201, 0.996])
.nice(5);
```
### Clamping
Restrict output to range bounds.
```javascript
const scale = d3.scaleLinear()
.domain([0, 100])
.range([0, 500])
.clamp(true);
scale(-10); // Returns 0 (clamped)
scale(150); // Returns 500 (clamped)
```
### Copy scales
Create independent copies.
```javascript
const scale1 = d3.scaleLinear()
.domain([0, 100])
.range([0, 500]);
const scale2 = scale1.copy();
// scale2 is independent of scale1
```
### Tick generation
Generate nice tick values for axes.
```javascript
const scale = d3.scaleLinear()
.domain([0, 100])
.range([0, 500]);
scale.ticks(10); // Generate ~10 ticks
scale.tickFormat(10); // Get format function for ticks
scale.tickFormat(10, ".2f"); // Custom format (2 decimal places)
// Time scale ticks
const timeScale = d3.scaleTime()
.domain([new Date(2020, 0, 1), new Date(2024, 0, 1)]);
timeScale.ticks(d3.timeYear); // Yearly ticks
timeScale.ticks(d3.timeMonth, 3); // Every 3 months
timeScale.tickFormat(5, "%Y-%m"); // Format as year-month
```
## Colour spaces and interpolation
### RGB interpolation
```javascript
const scale = d3.scaleLinear()
.domain([0, 100])
.range(["blue", "red"]);
// Default: RGB interpolation
```
### HSL interpolation
```javascript
const scale = d3.scaleLinear()
.domain([0, 100])
.range(["blue", "red"])
.interpolate(d3.interpolateHsl);
// Smoother colour transitions
```
### Lab interpolation
```javascript
const scale = d3.scaleLinear()
.domain([0, 100])
.range(["blue", "red"])
.interpolate(d3.interpolateLab);
// Perceptually uniform
```
### HCL interpolation
```javascript
const scale = d3.scaleLinear()
.domain([0, 100])
.range(["blue", "red"])
.interpolate(d3.interpolateHcl);
// Perceptually uniform with hue
```
## Common patterns
### Diverging scale with custom midpoint
```javascript
const scale = d3.scaleLinear()
.domain([min, midpoint, max])
.range(["red", "white", "blue"])
.interpolate(d3.interpolateHcl);
```
### Multi-stop gradient scale
```javascript
const scale = d3.scaleLinear()
.domain([0, 25, 50, 75, 100])
.range(["#d53e4f", "#fc8d59", "#fee08b", "#e6f598", "#66c2a5"]);
```
### Radius scale for circles (perceptual)
```javascript
const radiusScale = d3.scaleSqrt()
.domain([0, d3.max(data, d => d.value)])
.range([0, 50]);
// Use with circles
circle.attr("r", d => radiusScale(d.value));
```
### Adaptive scale based on data range
```javascript
function createAdaptiveScale(data) {
const extent = d3.extent(data);
const range = extent[1] - extent[0];
// Use log scale if data spans >2 orders of magnitude
if (extent[1] / extent[0] > 100) {
return d3.scaleLog()
.domain(extent)
.range([0, width]);
}
// Otherwise use linear
return d3.scaleLinear()
.domain(extent)
.range([0, width]);
}
```
### Colour scale with explicit categories
```javascript
const colourScale = d3.scaleOrdinal()
.domain(['Low Risk', 'Medium Risk', 'High Risk'])
.range(['#2ecc71', '#f39c12', '#e74c3c'])
.unknown('#95a5a6'); // Fallback for unknown values
```
@@ -0,0 +1,48 @@
---
name: data-quality-frameworks
description: "Implement data quality validation with Great Expectations, dbt tests, and data contracts. Use when building data quality pipelines, implementing validation rules, or establishing data contracts."
risk: unknown
source: community
date_added: "2026-02-27"
---
# Data Quality Frameworks
Production patterns for implementing data quality with Great Expectations, dbt tests, and data contracts to ensure reliable data pipelines.
## Use this skill when
- Implementing data quality checks in pipelines
- Setting up Great Expectations validation
- Building comprehensive dbt test suites
- Establishing data contracts between teams
- Monitoring data quality metrics
- Automating data validation in CI/CD
## Do not use this skill when
- The data sources are undefined or unavailable
- You cannot modify validation rules or schemas
- The task is unrelated to data quality or contracts
## Instructions
- Identify critical datasets and quality dimensions.
- Define expectations/tests and contract rules.
- Automate validation in CI/CD and schedule checks.
- Set alerting, ownership, and remediation steps.
- If detailed patterns are required, open `resources/implementation-playbook.md`.
## Safety
- Avoid blocking critical pipelines without a fallback plan.
- Handle sensitive data securely in validation outputs.
## Resources
- `resources/implementation-playbook.md` for detailed frameworks, templates, and examples.
## Limitations
- Use this skill only when the task clearly matches the scope described above.
- Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
- Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.
@@ -0,0 +1,573 @@
# Data Quality Frameworks Implementation Playbook
This file contains detailed patterns, checklists, and code samples referenced by the skill.
## Core Concepts
### 1. Data Quality Dimensions
| Dimension | Description | Example Check |
|-----------|-------------|---------------|
| **Completeness** | No missing values | `expect_column_values_to_not_be_null` |
| **Uniqueness** | No duplicates | `expect_column_values_to_be_unique` |
| **Validity** | Values in expected range | `expect_column_values_to_be_in_set` |
| **Accuracy** | Data matches reality | Cross-reference validation |
| **Consistency** | No contradictions | `expect_column_pair_values_A_to_be_greater_than_B` |
| **Timeliness** | Data is recent | `expect_column_max_to_be_between` |
### 2. Testing Pyramid for Data
```
/\
/ \ Integration Tests (cross-table)
/────\
/ \ Unit Tests (single column)
/────────\
/ \ Schema Tests (structure)
/────────────\
```
## Quick Start
### Great Expectations Setup
```bash
# Install
pip install great_expectations
# Initialize project
great_expectations init
# Create datasource
great_expectations datasource new
```
```python
# great_expectations/checkpoints/daily_validation.yml
import great_expectations as gx
# Create context
context = gx.get_context()
# Create expectation suite
suite = context.add_expectation_suite("orders_suite")
# Add expectations
suite.add_expectation(
gx.expectations.ExpectColumnValuesToNotBeNull(column="order_id")
)
suite.add_expectation(
gx.expectations.ExpectColumnValuesToBeUnique(column="order_id")
)
# Validate
results = context.run_checkpoint(checkpoint_name="daily_orders")
```
## Patterns
### Pattern 1: Great Expectations Suite
```python
# expectations/orders_suite.py
import great_expectations as gx
from great_expectations.core import ExpectationSuite
from great_expectations.core.expectation_configuration import ExpectationConfiguration
def build_orders_suite() -> ExpectationSuite:
"""Build comprehensive orders expectation suite"""
suite = ExpectationSuite(expectation_suite_name="orders_suite")
# Schema expectations
suite.add_expectation(ExpectationConfiguration(
expectation_type="expect_table_columns_to_match_set",
kwargs={
"column_set": ["order_id", "customer_id", "amount", "status", "created_at"],
"exact_match": False # Allow additional columns
}
))
# Primary key
suite.add_expectation(ExpectationConfiguration(
expectation_type="expect_column_values_to_not_be_null",
kwargs={"column": "order_id"}
))
suite.add_expectation(ExpectationConfiguration(
expectation_type="expect_column_values_to_be_unique",
kwargs={"column": "order_id"}
))
# Foreign key
suite.add_expectation(ExpectationConfiguration(
expectation_type="expect_column_values_to_not_be_null",
kwargs={"column": "customer_id"}
))
# Categorical values
suite.add_expectation(ExpectationConfiguration(
expectation_type="expect_column_values_to_be_in_set",
kwargs={
"column": "status",
"value_set": ["pending", "processing", "shipped", "delivered", "cancelled"]
}
))
# Numeric ranges
suite.add_expectation(ExpectationConfiguration(
expectation_type="expect_column_values_to_be_between",
kwargs={
"column": "amount",
"min_value": 0,
"max_value": 100000,
"strict_min": True # amount > 0
}
))
# Date validity
suite.add_expectation(ExpectationConfiguration(
expectation_type="expect_column_values_to_be_dateutil_parseable",
kwargs={"column": "created_at"}
))
# Freshness - data should be recent
suite.add_expectation(ExpectationConfiguration(
expectation_type="expect_column_max_to_be_between",
kwargs={
"column": "created_at",
"min_value": {"$PARAMETER": "now - timedelta(days=1)"},
"max_value": {"$PARAMETER": "now"}
}
))
# Row count sanity
suite.add_expectation(ExpectationConfiguration(
expectation_type="expect_table_row_count_to_be_between",
kwargs={
"min_value": 1000, # Expect at least 1000 rows
"max_value": 10000000
}
))
# Statistical expectations
suite.add_expectation(ExpectationConfiguration(
expectation_type="expect_column_mean_to_be_between",
kwargs={
"column": "amount",
"min_value": 50,
"max_value": 500
}
))
return suite
```
### Pattern 2: Great Expectations Checkpoint
```yaml
# great_expectations/checkpoints/orders_checkpoint.yml
name: orders_checkpoint
config_version: 1.0
class_name: Checkpoint
run_name_template: "%Y%m%d-%H%M%S-orders-validation"
validations:
- batch_request:
datasource_name: warehouse
data_connector_name: default_inferred_data_connector_name
data_asset_name: orders
data_connector_query:
index: -1 # Latest batch
expectation_suite_name: orders_suite
action_list:
- name: store_validation_result
action:
class_name: StoreValidationResultAction
- name: store_evaluation_parameters
action:
class_name: StoreEvaluationParametersAction
- name: update_data_docs
action:
class_name: UpdateDataDocsAction
# Slack notification on failure
- name: send_slack_notification
action:
class_name: SlackNotificationAction
slack_webhook: ${SLACK_WEBHOOK}
notify_on: failure
renderer:
module_name: great_expectations.render.renderer.slack_renderer
class_name: SlackRenderer
```
```python
# Run checkpoint
import great_expectations as gx
context = gx.get_context()
result = context.run_checkpoint(checkpoint_name="orders_checkpoint")
if not result.success:
failed_expectations = [
r for r in result.run_results.values()
if not r.success
]
raise ValueError(f"Data quality check failed: {failed_expectations}")
```
### Pattern 3: dbt Data Tests
```yaml
# models/marts/core/_core__models.yml
version: 2
models:
- name: fct_orders
description: Order fact table
tests:
# Table-level tests
- dbt_utils.recency:
datepart: day
field: created_at
interval: 1
- dbt_utils.at_least_one
- dbt_utils.expression_is_true:
expression: "total_amount >= 0"
columns:
- name: order_id
description: Primary key
tests:
- unique
- not_null
- name: customer_id
description: Foreign key to dim_customers
tests:
- not_null
- relationships:
to: ref('dim_customers')
field: customer_id
- name: order_status
tests:
- accepted_values:
values: ['pending', 'processing', 'shipped', 'delivered', 'cancelled']
- name: total_amount
tests:
- not_null
- dbt_utils.expression_is_true:
expression: ">= 0"
- name: created_at
tests:
- not_null
- dbt_utils.expression_is_true:
expression: "<= current_timestamp"
- name: dim_customers
columns:
- name: customer_id
tests:
- unique
- not_null
- name: email
tests:
- unique
- not_null
# Custom regex test
- dbt_utils.expression_is_true:
expression: "email ~ '^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,}$'"
```
### Pattern 4: Custom dbt Tests
```sql
-- tests/generic/test_row_count_in_range.sql
{% test row_count_in_range(model, min_count, max_count) %}
with row_count as (
select count(*) as cnt from {{ model }}
)
select cnt
from row_count
where cnt < {{ min_count }} or cnt > {{ max_count }}
{% endtest %}
-- Usage in schema.yml:
-- tests:
-- - row_count_in_range:
-- min_count: 1000
-- max_count: 10000000
```
```sql
-- tests/generic/test_sequential_values.sql
{% test sequential_values(model, column_name, interval=1) %}
with lagged as (
select
{{ column_name }},
lag({{ column_name }}) over (order by {{ column_name }}) as prev_value
from {{ model }}
)
select *
from lagged
where {{ column_name }} - prev_value != {{ interval }}
and prev_value is not null
{% endtest %}
```
```sql
-- tests/singular/assert_orders_customers_match.sql
-- Singular test: specific business rule
with orders_customers as (
select distinct customer_id from {{ ref('fct_orders') }}
),
dim_customers as (
select customer_id from {{ ref('dim_customers') }}
),
orphaned_orders as (
select o.customer_id
from orders_customers o
left join dim_customers c using (customer_id)
where c.customer_id is null
)
select * from orphaned_orders
-- Test passes if this returns 0 rows
```
### Pattern 5: Data Contracts
```yaml
# contracts/orders_contract.yaml
apiVersion: datacontract.com/v1.0.0
kind: DataContract
metadata:
name: orders
version: 1.0.0
owner: data-platform-team
contact: data-team@company.com
info:
title: Orders Data Contract
description: Contract for order event data from the ecommerce platform
purpose: Analytics, reporting, and ML features
servers:
production:
type: snowflake
account: company.us-east-1
database: ANALYTICS
schema: CORE
terms:
usage: Internal analytics only
limitations: PII must not be exposed in downstream marts
billing: Charged per query TB scanned
schema:
type: object
properties:
order_id:
type: string
format: uuid
description: Unique order identifier
required: true
unique: true
pii: false
customer_id:
type: string
format: uuid
description: Customer identifier
required: true
pii: true
piiClassification: indirect
total_amount:
type: number
minimum: 0
maximum: 100000
description: Order total in USD
created_at:
type: string
format: date-time
description: Order creation timestamp
required: true
status:
type: string
enum: [pending, processing, shipped, delivered, cancelled]
description: Current order status
quality:
type: SodaCL
specification:
checks for orders:
- row_count > 0
- missing_count(order_id) = 0
- duplicate_count(order_id) = 0
- invalid_count(status) = 0:
valid values: [pending, processing, shipped, delivered, cancelled]
- freshness(created_at) < 24h
sla:
availability: 99.9%
freshness: 1 hour
latency: 5 minutes
```
### Pattern 6: Automated Quality Pipeline
```python
# quality_pipeline.py
from dataclasses import dataclass
from typing import List, Dict, Any
import great_expectations as gx
from datetime import datetime
@dataclass
class QualityResult:
table: str
passed: bool
total_expectations: int
failed_expectations: int
details: List[Dict[str, Any]]
timestamp: datetime
class DataQualityPipeline:
"""Orchestrate data quality checks across tables"""
def __init__(self, context: gx.DataContext):
self.context = context
self.results: List[QualityResult] = []
def validate_table(self, table: str, suite: str) -> QualityResult:
"""Validate a single table against expectation suite"""
checkpoint_config = {
"name": f"{table}_validation",
"config_version": 1.0,
"class_name": "Checkpoint",
"validations": [{
"batch_request": {
"datasource_name": "warehouse",
"data_asset_name": table,
},
"expectation_suite_name": suite,
}],
}
result = self.context.run_checkpoint(**checkpoint_config)
# Parse results
validation_result = list(result.run_results.values())[0]
results = validation_result.results
failed = [r for r in results if not r.success]
return QualityResult(
table=table,
passed=result.success,
total_expectations=len(results),
failed_expectations=len(failed),
details=[{
"expectation": r.expectation_config.expectation_type,
"success": r.success,
"observed_value": r.result.get("observed_value"),
} for r in results],
timestamp=datetime.now()
)
def run_all(self, tables: Dict[str, str]) -> Dict[str, QualityResult]:
"""Run validation for all tables"""
results = {}
for table, suite in tables.items():
print(f"Validating {table}...")
results[table] = self.validate_table(table, suite)
return results
def generate_report(self, results: Dict[str, QualityResult]) -> str:
"""Generate quality report"""
report = ["# Data Quality Report", f"Generated: {datetime.now()}", ""]
total_passed = sum(1 for r in results.values() if r.passed)
total_tables = len(results)
report.append(f"## Summary: {total_passed}/{total_tables} tables passed")
report.append("")
for table, result in results.items():
status = "" if result.passed else ""
report.append(f"### {status} {table}")
report.append(f"- Expectations: {result.total_expectations}")
report.append(f"- Failed: {result.failed_expectations}")
if not result.passed:
report.append("- Failed checks:")
for detail in result.details:
if not detail["success"]:
report.append(f" - {detail['expectation']}: {detail['observed_value']}")
report.append("")
return "\n".join(report)
# Usage
context = gx.get_context()
pipeline = DataQualityPipeline(context)
tables_to_validate = {
"orders": "orders_suite",
"customers": "customers_suite",
"products": "products_suite",
}
results = pipeline.run_all(tables_to_validate)
report = pipeline.generate_report(results)
# Fail pipeline if any table failed
if not all(r.passed for r in results.values()):
print(report)
raise ValueError("Data quality checks failed!")
```
## Best Practices
### Do's
- **Test early** - Validate source data before transformations
- **Test incrementally** - Add tests as you find issues
- **Document expectations** - Clear descriptions for each test
- **Alert on failures** - Integrate with monitoring
- **Version contracts** - Track schema changes
### Don'ts
- **Don't test everything** - Focus on critical columns
- **Don't ignore warnings** - They often precede failures
- **Don't skip freshness** - Stale data is bad data
- **Don't hardcode thresholds** - Use dynamic baselines
- **Don't test in isolation** - Test relationships too
## Resources
- [Great Expectations Documentation](https://docs.greatexpectations.io/)
- [dbt Testing Documentation](https://docs.getdbt.com/docs/build/tests)
- [Data Contract Specification](https://datacontract.com/)
- [Soda Core](https://docs.soda.io/soda-core/overview.html)
@@ -0,0 +1,473 @@
---
name: data-storytelling
description: "Transform raw data into compelling narratives that drive decisions and inspire action."
risk: safe
source: community
date_added: "2026-02-27"
---
# Data Storytelling
Transform raw data into compelling narratives that drive decisions and inspire action.
## Do not use this skill when
- The task is unrelated to data storytelling
- You need a different domain or tool outside this scope
## Instructions
- Clarify goals, constraints, and required inputs.
- Apply relevant best practices and validate outcomes.
- Provide actionable steps and verification.
- If detailed examples are required, open `resources/implementation-playbook.md`.
## Use this skill when
- Presenting analytics to executives
- Creating quarterly business reviews
- Building investor presentations
- Writing data-driven reports
- Communicating insights to non-technical audiences
- Making recommendations based on data
## Core Concepts
### 1. Story Structure
```
Setup → Conflict → Resolution
Setup: Context and baseline
Conflict: The problem or opportunity
Resolution: Insights and recommendations
```
### 2. Narrative Arc
```
1. Hook: Grab attention with surprising insight
2. Context: Establish the baseline
3. Rising Action: Build through data points
4. Climax: The key insight
5. Resolution: Recommendations
6. Call to Action: Next steps
```
### 3. Three Pillars
| Pillar | Purpose | Components |
| ------------- | -------- | -------------------------------- |
| **Data** | Evidence | Numbers, trends, comparisons |
| **Narrative** | Meaning | Context, causation, implications |
| **Visuals** | Clarity | Charts, diagrams, highlights |
## Story Frameworks
### Framework 1: The Problem-Solution Story
```markdown
# Customer Churn Analysis
## The Hook
"We're losing $2.4M annually to preventable churn."
## The Context
- Current churn rate: 8.5% (industry average: 5%)
- Average customer lifetime value: $4,800
- 500 customers churned last quarter
## The Problem
Analysis of churned customers reveals a pattern:
- 73% churned within first 90 days
- Common factor: < 3 support interactions
- Low feature adoption in first month
## The Insight
[Show engagement curve visualization]
Customers who don't engage in the first 14 days
are 4x more likely to churn.
## The Solution
1. Implement 14-day onboarding sequence
2. Proactive outreach at day 7
3. Feature adoption tracking
## Expected Impact
- Reduce early churn by 40%
- Save $960K annually
- Payback period: 3 months
## Call to Action
Approve $50K budget for onboarding automation.
```
### Framework 2: The Trend Story
```markdown
# Q4 Performance Analysis
## Where We Started
Q3 ended with $1.2M MRR, 15% below target.
Team morale was low after missed goals.
## What Changed
[Timeline visualization]
- Oct: Launched self-serve pricing
- Nov: Reduced friction in signup
- Dec: Added customer success calls
## The Transformation
[Before/after comparison chart]
| Metric | Q3 | Q4 | Change |
|----------------|--------|--------|--------|
| Trial → Paid | 8% | 15% | +87% |
| Time to Value | 14 days| 5 days | -64% |
| Expansion Rate | 2% | 8% | +300% |
## Key Insight
Self-serve + high-touch creates compound growth.
Customers who self-serve AND get a success call
have 3x higher expansion rate.
## Going Forward
Double down on hybrid model.
Target: $1.8M MRR by Q2.
```
### Framework 3: The Comparison Story
```markdown
# Market Opportunity Analysis
## The Question
Should we expand into EMEA or APAC first?
## The Comparison
[Side-by-side market analysis]
### EMEA
- Market size: $4.2B
- Growth rate: 8%
- Competition: High
- Regulatory: Complex (GDPR)
- Language: Multiple
### APAC
- Market size: $3.8B
- Growth rate: 15%
- Competition: Moderate
- Regulatory: Varied
- Language: Multiple
## The Analysis
[Weighted scoring matrix visualization]
| Factor | Weight | EMEA Score | APAC Score |
| ----------- | ------ | ---------- | ---------- |
| Market Size | 25% | 5 | 4 |
| Growth | 30% | 3 | 5 |
| Competition | 20% | 2 | 4 |
| Ease | 25% | 2 | 3 |
| **Total** | | **2.9** | **4.1** |
## The Recommendation
APAC first. Higher growth, less competition.
Start with Singapore hub (English, business-friendly).
Enter EMEA in Year 2 with localization ready.
## Risk Mitigation
- Timezone coverage: Hire 24/7 support
- Cultural fit: Local partnerships
- Payment: Multi-currency from day 1
```
## Visualization Techniques
### Technique 1: Progressive Reveal
```markdown
Start simple, add layers:
Slide 1: "Revenue is growing" [single line chart]
Slide 2: "But growth is slowing" [add growth rate overlay]
Slide 3: "Driven by one segment" [add segment breakdown]
Slide 4: "Which is saturating" [add market share]
Slide 5: "We need new segments" [add opportunity zones]
```
### Technique 2: Contrast and Compare
```markdown
Before/After:
┌─────────────────┬─────────────────┐
│ BEFORE │ AFTER │
│ │ │
│ Process: 5 days│ Process: 1 day │
│ Errors: 15% │ Errors: 2% │
│ Cost: $50/unit │ Cost: $20/unit │
└─────────────────┴─────────────────┘
This/That (emphasize difference):
┌─────────────────────────────────────┐
│ CUSTOMER A vs B │
│ ┌──────────┐ ┌──────────┐ │
│ │ ████████ │ │ ██ │ │
│ │ $45,000 │ │ $8,000 │ │
│ │ LTV │ │ LTV │ │
│ └──────────┘ └──────────┘ │
│ Onboarded No onboarding │
└─────────────────────────────────────┘
```
### Technique 3: Annotation and Highlight
```python
import matplotlib.pyplot as plt
import pandas as pd
fig, ax = plt.subplots(figsize=(12, 6))
# Plot the main data
ax.plot(dates, revenue, linewidth=2, color='#2E86AB')
# Add annotation for key events
ax.annotate(
'Product Launch\n+32% spike',
xy=(launch_date, launch_revenue),
xytext=(launch_date, launch_revenue * 1.2),
fontsize=10,
arrowprops=dict(arrowstyle='->', color='#E63946'),
color='#E63946'
)
# Highlight a region
ax.axvspan(growth_start, growth_end, alpha=0.2, color='green',
label='Growth Period')
# Add threshold line
ax.axhline(y=target, color='gray', linestyle='--',
label=f'Target: ${target:,.0f}')
ax.set_title('Revenue Growth Story', fontsize=14, fontweight='bold')
ax.legend()
```
## Presentation Templates
### Template 1: Executive Summary Slide
```
┌─────────────────────────────────────────────────────────────┐
│ KEY INSIGHT │
│ ══════════════════════════════════════════════════════════│
│ │
│ "Customers who complete onboarding in week 1 │
│ have 3x higher lifetime value" │
│ │
├──────────────────────┬──────────────────────────────────────┤
│ │ │
│ THE DATA │ THE IMPLICATION │
│ │ │
│ Week 1 completers: │ ✓ Prioritize onboarding UX │
│ • LTV: $4,500 │ ✓ Add day-1 success milestones │
│ • Retention: 85% │ ✓ Proactive week-1 outreach │
│ • NPS: 72 │ │
│ │ Investment: $75K │
│ Others: │ Expected ROI: 8x │
│ • LTV: $1,500 │ │
│ • Retention: 45% │ │
│ • NPS: 34 │ │
│ │ │
└──────────────────────┴──────────────────────────────────────┘
```
### Template 2: Data Story Flow
```
Slide 1: THE HEADLINE
"We can grow 40% faster by fixing onboarding"
Slide 2: THE CONTEXT
Current state metrics
Industry benchmarks
Gap analysis
Slide 3: THE DISCOVERY
What the data revealed
Surprising finding
Pattern identification
Slide 4: THE DEEP DIVE
Root cause analysis
Segment breakdowns
Statistical significance
Slide 5: THE RECOMMENDATION
Proposed actions
Resource requirements
Timeline
Slide 6: THE IMPACT
Expected outcomes
ROI calculation
Risk assessment
Slide 7: THE ASK
Specific request
Decision needed
Next steps
```
### Template 3: One-Page Dashboard Story
```markdown
# Monthly Business Review: January 2024
## THE HEADLINE
Revenue up 15% but CAC increasing faster than LTV
## KEY METRICS AT A GLANCE
┌────────┬────────┬────────┬────────┐
│ MRR │ NRR │ CAC │ LTV │
│ $125K │ 108% │ $450 │ $2,200 │
│ ▲15% │ ▲3% │ ▲22% │ ▲8% │
└────────┴────────┴────────┴────────┘
## WHAT'S WORKING
✓ Enterprise segment growing 25% MoM
✓ Referral program driving 30% of new logos
✓ Support satisfaction at all-time high (94%)
## WHAT NEEDS ATTENTION
✗ SMB acquisition cost up 40%
✗ Trial conversion down 5 points
✗ Time-to-value increased by 3 days
## ROOT CAUSE
[Mini chart showing SMB vs Enterprise CAC trend]
SMB paid ads becoming less efficient.
CPC up 35% while conversion flat.
## RECOMMENDATION
1. Shift $20K/mo from paid to content
2. Launch SMB self-serve trial
3. A/B test shorter onboarding
## NEXT MONTH'S FOCUS
- Launch content marketing pilot
- Complete self-serve MVP
- Reduce time-to-value to < 7 days
```
## Writing Techniques
### Headlines That Work
```markdown
BAD: "Q4 Sales Analysis"
GOOD: "Q4 Sales Beat Target by 23% - Here's Why"
BAD: "Customer Churn Report"
GOOD: "We're Losing $2.4M to Preventable Churn"
BAD: "Marketing Performance"
GOOD: "Content Marketing Delivers 4x ROI vs. Paid"
Formula:
[Specific Number] + [Business Impact] + [Actionable Context]
```
### Transition Phrases
```markdown
Building the narrative:
• "This leads us to ask..."
• "When we dig deeper..."
• "The pattern becomes clear when..."
• "Contrast this with..."
Introducing insights:
• "The data reveals..."
• "What surprised us was..."
• "The inflection point came when..."
• "The key finding is..."
Moving to action:
• "This insight suggests..."
• "Based on this analysis..."
• "The implication is clear..."
• "Our recommendation is..."
```
### Handling Uncertainty
```markdown
Acknowledge limitations:
• "With 95% confidence, we can say..."
• "The sample size of 500 shows..."
• "While correlation is strong, causation requires..."
• "This trend holds for [segment], though [caveat]..."
Present ranges:
• "Impact estimate: $400K-$600K"
• "Confidence interval: 15-20% improvement"
• "Best case: X, Conservative: Y"
```
## Best Practices
### Do's
- **Start with the "so what"** - Lead with insight
- **Use the rule of three** - Three points, three comparisons
- **Show, don't tell** - Let data speak
- **Make it personal** - Connect to audience goals
- **End with action** - Clear next steps
### Don'ts
- **Don't data dump** - Curate ruthlessly
- **Don't bury the insight** - Front-load key findings
- **Don't use jargon** - Match audience vocabulary
- **Don't show methodology first** - Context, then method
- **Don't forget the narrative** - Numbers need meaning
## Resources
- [Storytelling with Data (Cole Nussbaumer)](https://www.storytellingwithdata.com/)
- [The Pyramid Principle (Barbara Minto)](https://www.amazon.com/Pyramid-Principle-Logic-Writing-Thinking/dp/0273710516)
- [Resonate (Nancy Duarte)](https://www.duarte.com/resonate/)
## Limitations
- Use this skill only when the task clearly matches the scope described above.
- Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
- Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.