d3-viz

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);

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

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);

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

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();
}

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'));

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);

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);

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
    .attr("text-anchor", d => d.angle > Math.PI ? "end" : null)
    .text((d, i) => nodes[i])
    .style("font-size", "12px");
}

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);
}

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);

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;
}

// 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");
  });

const zoom = d3.zoom()
  .scaleExtent([0.5, 10])
  .on("zoom", (event) => {
    g.attr("transform", event.transform);
  });
 
svg.call(zoom);

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 }));
  });

// 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);

// 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]);

// 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 colour scale
const colourScale = d3.scaleSequential(d3.interpolateBlues)
  .domain([0, 100]);
 
// Diverging colour scale
const divScale = d3.scaleDiverging(d3.interpolateRdBu)
  .domain([-10, 0, 10]);

// 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)
}));

// 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

// 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

// 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");