Two Linked Pie Charts with a Legend
Two donuts, one legend: the same four countries in two groups side by side, each with its total in the middle. Point at a slice and its twin lights up in the other donut.
About this chart
When two pies beat one
Two pies compare how two groups split the same categories: this year and last, or two regions. The shared legend and the linked hover tie the colors together, so the eye can jump between them. For exact differences, a grouped bar chart is still clearer.
Good for
- Two years, two regions or two teams
- Before and after a change
- Groups of very different size: each donut shows its own total
Think twice when
- More than two or three groups: use 100% stacked columns
- Small changes in share: they are hard to spot between pies
- Different categories in each pie: one legend can’t cover both
For developers
Get the code.
Built with amCharts 5, a JavaScript library. The code includes your theme and renderer (canvas or SVG), but not the changes you make with the controls.
For projects that use npm:
How it reads:
npm install @amcharts/amcharts5. See Getting started.
The same chart as a JSON config. Chart Maker reads and writes this format, the library's JSON parser turns it into a chart, and the <am5-chart> element puts it on a page with no code.How it reads:
"type" is the class to create and "settings" what you would pass to its new() in code; "properties" fill in its parts, lists such as series and axes or templates such as columns.template; "refs" holds objects used in more than one place ("#series-0" stands for the one named series-0); a string starting with "@" takes a value from another object, such as "@series.get('fill')".
A complete page. Save it as an .html file and open it in a browser.
Paste this into an AI coding assistant to build the chart from scratch. More in amCharts & AI.
// Create root element
// https://docs.amcharts.com/v5/getting-started/#root-element
var root = am5.Root.new("chartdiv");
// Set themes
// https://docs.amcharts.com/v5/concepts/themes/
root.setThemes([
am5themes_Animated.new(root),
am5themes_Responsive.new(root)
]);
// the two charts on top, the shared legend under them
root.container.set("layout", root.verticalLayout);
// Create container to hold charts
var chartContainer = root.container.children.push(am5.Container.new(root, {
layout: root.horizontalLayout, // the two charts side by side
width: am5.p100, // filling the space the legend leaves
height: am5.p100
}));
// Create the 1st chart
// https://docs.amcharts.com/v5/charts/percent-charts/pie-chart/
var chart = chartContainer.children.push(
am5percent.PieChart.new(root, {
endAngle: 270, // the ring ends at the top, where it starts: a full circle
innerRadius: am5.percent(60) // a hole 60% of the radius wide, for the total
})
);
var series = chart.series.push(
am5percent.PieSeries.new(root, {
valueField: "value",
categoryField: "category",
endAngle: 270,
alignLabels: false // the names follow the ring, not lined up in columns
})
);
// the total in the middle of the ring: {valueSum} adds up the series' values
series.children.push(am5.Label.new(root, {
centerX: am5.percent(50), // centered in the hole
centerY: am5.percent(50),
text: "First: {valueSum}",
populateText: true, // fills in {valueSum}
fontSize: "1.5em" // 1.5 times the chart's text size
}));
series.slices.template.setAll({
cornerRadius: 8 // rounded slice corners
})
// hidden, the ring closes up at the top, so it sweeps open clockwise on load
series.states.create("hidden", {
endAngle: -90
});
// names only along the ring; the shares are in the tooltips and the legend
series.labels.template.setAll({
textType: "circular",
text: "{category}"
});
// Create the 2nd chart
// https://docs.amcharts.com/v5/charts/percent-charts/pie-chart/
var chart2 = chartContainer.children.push(
am5percent.PieChart.new(root, {
endAngle: 270,
innerRadius: am5.percent(60)
})
);
var series2 = chart2.series.push(
am5percent.PieSeries.new(root, {
valueField: "value",
categoryField: "category",
endAngle: 270,
alignLabels: false,
tooltip: am5.Tooltip.new(root, {}) // a separate tooltip needed for this series
})
);
series2.children.push(am5.Label.new(root, {
centerX: am5.percent(50),
centerY: am5.percent(50),
text: "Second: {valueSum}",
populateText: true,
fontSize: "1.5em"
}));
series2.slices.template.setAll({
cornerRadius: 8
})
series2.states.create("hidden", {
endAngle: -90
});
series2.labels.template.setAll({
textType: "circular",
text: "{category}"
});
// Duplicate interaction
// Must be added before setting data
series.slices.template.events.on("pointerover", function(ev) {
var slice = ev.target;
var dataItem = slice.dataItem;
var otherSlice = getSlice(dataItem, series2);
if (otherSlice) {
otherSlice.hover();
}
});
// and unhover it when the pointer leaves
series.slices.template.events.on("pointerout", function(ev) {
var slice = ev.target;
var dataItem = slice.dataItem;
var otherSlice = getSlice(dataItem, series2);
if (otherSlice) {
otherSlice.unhover();
}
});
// a click that pulls a slice out pulls out the same country in the other chart
series.slices.template.on("active", function(active, target) {
var slice = target;
var dataItem = slice.dataItem;
var otherSlice = getSlice(dataItem, series2);
if (otherSlice) {
otherSlice.set("active", active);
}
});
// Same for the 2nd series
series2.slices.template.events.on("pointerover", function(ev) {
var slice = ev.target;
var dataItem = slice.dataItem;
var otherSlice = getSlice(dataItem, series);
if (otherSlice) {
otherSlice.hover();
}
});
series2.slices.template.events.on("pointerout", function(ev) {
var slice = ev.target;
var dataItem = slice.dataItem;
var otherSlice = getSlice(dataItem, series);
if (otherSlice) {
otherSlice.unhover();
}
});
series2.slices.template.on("active", function(active, target) {
var slice = target;
var dataItem = slice.dataItem;
var otherSlice = getSlice(dataItem, series);
if (otherSlice) {
otherSlice.set("active", active);
}
});
// Set data
// https://docs.amcharts.com/v5/charts/percent-charts/pie-chart/#setting-data
series.data.setAll([{
category: "Lithuania",
value: 501
}, {
category: "Czechia",
value: 301
}, {
category: "Ireland",
value: 201
}, {
category: "Germany",
value: 165
}]);
// Set data
// https://docs.amcharts.com/v5/charts/percent-charts/pie-chart/#setting-data
series2.data.setAll([{
category: "Lithuania",
value: 201
}, {
category: "Czechia",
value: 101
}, {
category: "Ireland",
value: 51
}, {
category: "Germany",
value: 15
}]);
// finds the slice for the same country in the given series
function getSlice(dataItem, series) {
var otherSlice;
am5.array.each(series.dataItems, function(di) {
if (di.get("category") === dataItem.get("category")) {
otherSlice = di.get("slice");
}
});
return otherSlice;
}
// Create legend
var legend = root.container.children.push(am5.Legend.new(root, {
x: am5.percent(50), // centered under the charts
centerX: am5.percent(50)
}));
// Trigger all the same for the 2nd series
legend.itemContainers.template.events.on("pointerover", function(ev) {
var dataItem = ev.target.dataItem.dataContext;
var slice = getSlice(dataItem, series2);
slice.hover();
});
// and unhover it again
legend.itemContainers.template.events.on("pointerout", function(ev) {
var dataItem = ev.target.dataItem.dataContext;
var slice = getSlice(dataItem, series2);
slice.unhover();
});
// a legend click hides or shows the country in the second chart too
legend.itemContainers.template.on("disabled", function(disabled, target) {
var dataItem = target.dataItem.dataContext;
var slice = getSlice(dataItem, series2);
if (disabled) {
series2.hideDataItem(slice.dataItem);
}
else {
series2.showDataItem(slice.dataItem);
}
});
// one legend for both charts: it lists the first chart's slices, the code above mirrors them
legend.data.setAll(series.dataItems);
series.appear(1000, 100);
