This document describes how to build a stacked barplot with subgroup highlighting available on hover. It follows the previous basic stacked barplot. Main stacked barchar caveats is that subgroups can be hard to compare since not aligned. Highlighting one allows to counter balance this issue. This example works with d3.js v4 and v6
d3.select(this.parentNode).datum().key. Then it is easy to change the opacity of all rects to something low, and highlight the selected subgroup with a higher opacity. <!DOCTYPE html>
<meta charset="utf-8">
<!-- Load d3.js & color palette-->
<script src="https://d3js.org/d3.v4.js"></script>
<script src="https://d3js.org/d3-scale-chromatic.v1.min.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: 10, right: 30, bottom: 20, left: 50},
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/D3-graph-gallery/master/DATA/data_stackedXL.csv", function(data) {
// List of subgroups = header of the csv files = soil condition here
var subgroups = data.columns.slice(1)
// List of groups = species here = value of the first column called group -> I show them on the X axis
var groups = d3.map(data, function(d){return(d.group)}).keys()
// Add X axis
var x = d3.scaleBand()
.domain(groups)
.range([0, width])
.padding([0.2])
svg.append("g")
.attr("transform", "translate(0," + height + ")")
.call(d3.axisBottom(x).tickSizeOuter(0));
// Add Y axis
var y = d3.scaleLinear()
.domain([0, 120])
.range([ height, 0 ]);
svg.append("g")
.call(d3.axisLeft(y));
// color palette = one color per subgroup
var color = d3.scaleOrdinal()
.domain(subgroups)
.range(d3.schemeSet2);
//stack the data? --> stack per subgroup
var stackedData = d3.stack()
.keys(subgroups)
(data)
// ----------------
// Highlight a specific subgroup when hovered
// ----------------
// What happens when user hover a bar
var mouseover = function(d) {
// what subgroup are we hovering?
var subgroupName = d3.select(this.parentNode).datum().key; // This was the tricky part
var subgroupValue = d.data[subgroupName];
// Reduce opacity of all rect to 0.2
d3.selectAll(".myRect").style("opacity", 0.2)
// Highlight all rects of this subgroup with opacity 0.8. It is possible to select them since they have a specific class = their name.
d3.selectAll("."+subgroupName)
.style("opacity", 1)
}
// When user do not hover anymore
var mouseleave = function(d) {
// Back to normal opacity: 0.8
d3.selectAll(".myRect")
.style("opacity",0.8)
}
// Show the bars
svg.append("g")
.selectAll("g")
// Enter in the stack data = loop key per key = group per group
.data(stackedData)
.enter().append("g")
.attr("fill", function(d) { return color(d.key); })
.attr("class", function(d){ return "myRect " + d.key }) // Add a class to each subgroup: their name
.selectAll("rect")
// enter a second time = loop subgroup per subgroup to add all rectangles
.data(function(d) { return d; })
.enter().append("rect")
.attr("x", function(d) { return x(d.data.group); })
.attr("y", function(d) { return y(d[1]); })
.attr("height", function(d) { return y(d[0]) - y(d[1]); })
.attr("width",x.bandwidth())
.attr("stroke", "grey")
.on("mouseover", mouseover)
.on("mouseleave", mouseleave)
})
</script> <script>
// set the dimensions and margins of the graph
const margin = {top: 10, right: 30, bottom: 20, left: 50},
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/D3-graph-gallery/master/DATA/data_stackedXL.csv").then( function(data) {
// List of subgroups = header of the csv files = soil condition here
const subgroups = data.columns.slice(1)
// List of groups = species here = value of the first column called group -> I show them on the X axis
const groups = data.map(d => d.group)
// Add X axis
const x = d3.scaleBand()
.domain(groups)
.range([0, width])
.padding([0.2])
svg.append("g")
.attr("transform", `translate(0, ${height})`)
.call(d3.axisBottom(x).tickSizeOuter(0));
// Add Y axis
const y = d3.scaleLinear()
.domain([0, 120])
.range([ height, 0 ]);
svg.append("g")
.call(d3.axisLeft(y));
// color palette = one color per subgroup
const color = d3.scaleOrdinal()
.domain(subgroups)
.range(d3.schemeSet2);
//stack the data? --> stack per subgroup
const stackedData = d3.stack()
.keys(subgroups)
(data)
// ----------------
// Highlight a specific subgroup when hovered
// ----------------
// Show the bars
svg.append("g")
.selectAll("g")
// Enter in the stack data = loop key per key = group per group
.data(stackedData)
.join("g")
.attr("fill", d => color(d.key))
.attr("class", d => "myRect " + d.key ) // Add a class to each subgroup: their name
.selectAll("rect")
// enter a second time = loop subgroup per subgroup to add all rectangles
.data(d => d)
.join("rect")
.attr("x", d => x(d.data.group))
.attr("y", d => y(d[1]))
.attr("height", d => y(d[0]) - y(d[1]))
.attr("width",x.bandwidth())
.attr("stroke", "grey")
.on("mouseover", function (event,d) { // What happens when user hover a bar
// what subgroup are we hovering?
const subGroupName = d3.select(this.parentNode).datum().key
// Reduce opacity of all rect to 0.2
d3.selectAll(".myRect").style("opacity", 0.2)
// Highlight all rects of this subgroup with opacity 1. It is possible to select them since they have a specific class = their name.
d3.selectAll("."+subGroupName).style("opacity",1)
})
.on("mouseleave", function (event,d) { // When user do not hover anymore
// Back to normal opacity: 1
d3.selectAll(".myRect")
.style("opacity",1)
})
})
</script>