Grouped bar chart with D3
Grouped bar charts are a type of colour-coded bar chart that is used to represent and compare different categories of two or more groups.
More about: Grouped bar chart
Grouped bar chart
<!DOCTYPE html>
<meta charset="utf-8">
<!-- Include d3 library -->
<script src="https://d3js.org/d3.v7.min.js"></script>
<!-- Create a container to host the chart -->
<div id="viz_container"></div>
// set the dimensions and margins of the graph
const margin = {top: 100, right: 20, bottom: 50, left: 190};
const width = 450 - margin.left - margin.right;
const height = 350 - margin.top - margin.bottom;
// append the svg object to the body of the page
const svg = d3.select("#viz_container")
.append("svg")
.attr("width", "100%")
.attr("height", "100%")
.attr("viewBox", "0 0 450 350")
.attr("preserveAspectRatio", "xMinYMin")
.append("g")
.attr("transform", `translate(${margin.left}, ${margin.top})`);
// parse the Data
d3.csv("https://raw.githubusercontent.com/GDS-ODSSS/unhcr-dataviz-platform/master/data/comparison/bar_grouped.csv")
.then(function(data){
const sumbyRegionYear = d3.rollups(data, v => d3.sum(v, d => d.asylum_application), d => d.region, d => d.year)
const regionKey = Array.from(sumbyRegionYear).map(d => d[0])
const yearKeys = Array.from(Array.from(sumbyRegionYear)[0][1]).map(d=>d[0])
const regionKeys = regionKey.sort(d3.ascending)
// x scale and Axis
const xScale = d3.scaleLinear()
.domain([0, d3.max(data.map(d => d.asylum_application))]).nice()
.range([0, width]);
svg
.append('g')
.attr("transform", "translate(0, "+ height +")")
.call(d3.axisBottom(xScale).tickSize(0).ticks(5).tickPadding(6).tickFormat(d3.format(".1s")))
.call(d => d.select(".domain").remove());
// y scale and Axis
const yScale = d3.scaleBand()
.domain(regionKeys)
.range([0, height])
.padding(.2);
svg
.append('g')
.call(d3.axisLeft(yScale).tickSize(0).tickPadding(8));
// set subgroup sacle
const ySubgroups = d3.scaleBand()
.domain(yearKeys)
.range([0, yScale.bandwidth()])
.padding([0.05])
// color palette
const color = d3.scaleOrdinal()
.domain(yearKeys)
.range(['#0072BC','#8EBEFF'])
// set vertical grid line
const GridLine = () => d3.axisBottom().scale(xScale);
svg
.append("g")
.attr("class", "grid")
.call(GridLine()
.tickSize(height,0,0)
.tickFormat("")
.ticks(6)
);
// create a tooltip
const tooltip = d3.select("body")
.append("div")
.attr("id", "chart")
.attr("class", "tooltip");
// tooltip events
const mouseover = function(d) {
tooltip
.style("opacity", .8)
d3.select(this)
.style("opacity", .5)
}
const mousemove = function(event, d) {
const formater = d3.format(",")
tooltip
.html(formater(d[1]))
.style("top", event.pageY - 10 + "px")
.style("left", event.pageX + 10 + "px");
}
const mouseleave = function(d) {
tooltip
.style("opacity", 0)
d3.select(this)
.style("opacity", 1)
}
// create bars
bars = svg.append("g")
.selectAll("g")
.data(sumbyRegionYear)
.join("g")
.attr("transform", d => "translate(0, " + yScale(d[0]) +")")
.selectAll("rect")
.data(d => { return d[1] })
.join("rect")
.attr("x", xScale(0))
.attr("y", d => ySubgroups(d[0]))
.attr("width", d => xScale(d[1]))
.attr("height", ySubgroups.bandwidth())
.attr("fill", d=>color(d[0]))
.on("mouseover", mouseover)
.on("mousemove", mousemove)
.on("mouseleave", mouseleave);
// set title
svg
.append("text")
.attr("class", "chart-title")
.attr("x", -(margin.left)*0.7)
.attr("y", -(margin.top)/1.5)
.attr("text-anchor", "start")
.text("Individual asylum applications registred by region | 2019-2020")
// set Y axis label
svg
.append("text")
.attr("class", "chart-label")
.attr("x", width/2)
.attr("y", height+margin.bottom/2)
.attr("text-anchor", "middle")
.text("Displaced population")
// set source
svg
.append("text")
.attr("class", "chart-source")
.attr("x", -(margin.left)*0.7)
.attr("y", height + margin.bottom*0.7)
.attr("text-anchor", "start")
.text("Source: UNHCR Refugee Data Finder")
// set copyright
svg
.append("text")
.attr("class", "copyright")
.attr("x", -(margin.left)*0.7)
.attr("y", height + margin.bottom*0.9)
.attr("text-anchor", "start")
.text("©UNHCR, The UN Refugee Agency")
//set legend
svg
.append("rect")
.attr("x", -(margin.left)*0.7)
.attr("y", -(margin.top/2))
.attr("width", 13)
.attr("height", 13)
.style("fill", "#0072BC");
svg
.append("text")
.attr("class", "legend")
.attr("x", -(margin.left)*0.7+20)
.attr("y", -(margin.top/2.5))
.text("2019")
svg
.append("rect")
.attr("x", -(margin.left)*0.7+60)
.attr("y", -(margin.top/2))
.attr("width", 13)
.attr("height", 13)
.style("fill", "#8EBEFF")
svg
.append("text")
.attr("class", "legend")
.attr("x", -(margin.left)*0.7+80)
.attr("y", -(margin.top/2.5))
.text("2020")
})
