Most basic streamgraph in d3.js





This post describes how to build a very basic streamgraph with d3.js. You can see many other examples in the streamgraph section of the gallery. Learn more about the theory of streamgraphs in data-to-viz.com. This example works with d3.js v4 and v6


Streamgraph section

Steps:

  • The Html part of the code just creates a div that will be modified by d3 later on.

  • The first part of the javascript code set a svg area. It specify the chart size and its margin. Read more.

  • To build a streamgraph, data must be stacked, using the d3.stack() function.

  • Once the new coordinates are available, shapes can be added through path, using the d3.area() helper.
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<!DOCTYPE html>
<meta charset="utf-8">

<!-- Load d3.js -->
<script src="https://d3js.org/d3.v4.js"></script>

<!-- Create a div where the graph will take place -->
<div id="my_dataviz"></div>

<!DOCTYPE html>
<meta charset="utf-8">
        
<!-- Load d3.js -->
<script src="https://d3js.org/d3.v6.js"></script>
        
<!-- Create a div where the graph will take place -->
<div id="my_dataviz"></div>
    
<script>

// set the dimensions and margins of the graph
var margin = {top: 20, right: 30, bottom: 30, left: 60},
    width = 460 - margin.left - margin.right,
    height = 400 - margin.top - margin.bottom;

// append the svg object to the body of the page
var svg = d3.select("#my_dataviz")
  .append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform",
          "translate(" + margin.left + "," + margin.top + ")");

// Parse the Data
d3.csv("https://raw.githubusercontent.com/holtzy/data_to_viz/master/Example_dataset/5_OneCatSevNumOrdered_wide.csv", function(data) {

  // List of groups = header of the csv files
  var keys = data.columns.slice(1)

  // Add X axis
  var x = d3.scaleLinear()
    .domain(d3.extent(data, function(d) { return d.year; }))
    .range([ 0, width ]);
  svg.append("g")
    .attr("transform", "translate(0," + height + ")")
    .call(d3.axisBottom(x).ticks(5));

  // Add Y axis
  var y = d3.scaleLinear()
    .domain([-100000, 100000])
    .range([ height, 0 ]);
  svg.append("g")
    .call(d3.axisLeft(y));

  // color palette
  var color = d3.scaleOrdinal()
    .domain(keys)
    .range(['#e41a1c','#377eb8','#4daf4a','#984ea3','#ff7f00','#ffff33','#a65628','#f781bf'])

  //stack the data?
  var stackedData = d3.stack()
    .offset(d3.stackOffsetSilhouette)
    .keys(keys)
    (data)

  // Show the areas
  svg
    .selectAll("mylayers")
    .data(stackedData)
    .enter()
    .append("path")
      .style("fill", function(d) { return color(d.key); })
      .attr("d", d3.area()
        .x(function(d, i) { return x(d.data.year); })
        .y0(function(d) { return y(d[0]); })
        .y1(function(d) { return y(d[1]); })
    )

})
</script>
<script>

// set the dimensions and margins of the graph
const margin = {top: 20, right: 30, bottom: 30, left: 60},
    width = 460 - margin.left - margin.right,
    height = 400 - margin.top - margin.bottom;

// append the svg object to the body of the page
const svg = d3.select("#my_dataviz")
  .append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform",
          `translate(${margin.left}, ${margin.top})`);

// Parse the Data
d3.csv("https://raw.githubusercontent.com/holtzy/data_to_viz/master/Example_dataset/5_OneCatSevNumOrdered_wide.csv").then( function(data) {

  // List of groups = header of the csv files
  const keys = data.columns.slice(1)

  // Add X axis
  const x = d3.scaleLinear()
    .domain(d3.extent(data, function(d) { return d.year; }))
    .range([ 0, width ]);
  svg.append("g")
    .attr("transform", `translate(0, ${height})`)
    .call(d3.axisBottom(x).ticks(5));

  // Add Y axis
  const y = d3.scaleLinear()
    .domain([-100000, 100000])
    .range([ height, 0 ]);
  svg.append("g")
    .call(d3.axisLeft(y));

  // color palette
  const color = d3.scaleOrdinal()
    .domain(keys)
    .range(['#e41a1c','#377eb8','#4daf4a','#984ea3','#ff7f00','#ffff33','#a65628','#f781bf'])

  //stack the data?
  const stackedData = d3.stack()
    .offset(d3.stackOffsetSilhouette)
    .keys(keys)
    (data)

  // Show the areas
  svg
    .selectAll("mylayers")
    .data(stackedData)
    .join("path")
      .style("fill", function(d) { return color(d.key); })
      .attr("d", d3.area()
        .x(function(d, i) { return x(d.data.year); })
        .y0(function(d) { return y(d[0]); })
        .y1(function(d) { return y(d[1]); })
    )

})
</script>

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