Most basic barplot in d3.js





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


Barplot 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.

  • Data shows the amount of sold weapon per country. See data-to-viz if interested.

  • First step consists to make a numeric (Y axis) and a categoric scale (X axis). Read here to understand how scales and axis work.

  • Finally, the bars can be added using rectangle
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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: 30, right: 30, bottom: 70, 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/7_OneCatOneNum_header.csv", function(data) {

// X axis
var x = d3.scaleBand()
  .range([ 0, width ])
  .domain(data.map(function(d) { return d.Country; }))
  .padding(0.2);
svg.append("g")
  .attr("transform", "translate(0," + height + ")")
  .call(d3.axisBottom(x))
  .selectAll("text")
    .attr("transform", "translate(-10,0)rotate(-45)")
    .style("text-anchor", "end");

// Add Y axis
var y = d3.scaleLinear()
  .domain([0, 13000])
  .range([ height, 0]);
svg.append("g")
  .call(d3.axisLeft(y));

// Bars
svg.selectAll("mybar")
  .data(data)
  .enter()
  .append("rect")
    .attr("x", function(d) { return x(d.Country); })
    .attr("y", function(d) { return y(d.Value); })
    .attr("width", x.bandwidth())
    .attr("height", function(d) { return height - y(d.Value); })
    .attr("fill", "#69b3a2")

})

</script>
<script>

// set the dimensions and margins of the graph
const margin = {top: 30, right: 30, bottom: 70, 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/7_OneCatOneNum_header.csv").then( function(data) {

// X axis
const x = d3.scaleBand()
  .range([ 0, width ])
  .domain(data.map(d => d.Country))
  .padding(0.2);
svg.append("g")
  .attr("transform", `translate(0, ${height})`)
  .call(d3.axisBottom(x))
  .selectAll("text")
    .attr("transform", "translate(-10,0)rotate(-45)")
    .style("text-anchor", "end");

// Add Y axis
const y = d3.scaleLinear()
  .domain([0, 13000])
  .range([ height, 0]);
svg.append("g")
  .call(d3.axisLeft(y));

// Bars
svg.selectAll("mybar")
  .data(data)
  .join("rect")
    .attr("x", d => x(d.Country))
    .attr("y", d => y(d.Value))
    .attr("width", x.bandwidth())
    .attr("height", d => height - y(d.Value))
    .attr("fill", "#69b3a2")

})
</script>

Related blocks →

  • Simple bar graph in v4 - link

  • Let's make a bar chart - link