Implement Heatmaps using HighCharts in React

Introduction

HightCharts is a powerful library for creating data visualizations, It comes with many tools that allow to creation of a reliable and secure chart.

This article will demonstrate how we can implement a heat map using Highcharts in React.

Full source code:

• Stackblitz

Pre-requests:

We need to install the following npm packages related to hightcharts and highcharts-react-official:

• highcharts
• highcharts-react-official

Let’s install them:

Yarn

yarn add highcharts-react-official highcharts

NPM

npm install highcharts-react-official highcharts

---

Heatmap example

In this example, we’re going to implement a week/day (24 hours) heatmap.

Let’s start by creating a HeatMap.js React component and add our implementation into it.

First, we need to import the required Highcharts utils:

import Highcharts from "highcharts";
import HighchartsHeatmap from "highcharts/modules/heatmap";
import HighchartsReact from "highcharts-react-official";

Next, we need to inject HighchartsHeatmap the module into Highcharts wrapper.

HighchartsHeatmap(Highcharts);

---

Now we can use the React component in our implementation as the following:

<HighchartsReact />

but would result in the following warnings:

1. The “highcharts” property was not passed.
2. The “options” property was not passed.

Adding the highcharts property would result in the following:

<HighchartsReact highcharts={Highcharts} />

Now, let’s dig into the options property and understand the details of it.

---

Heatmap Options

Let’s create an object and add the following properties into it:

// 1- Create Y-axis labels
const WEEK_DAYS = [
  'Sunday',
  'Monday',
  'Tuesday',
  'Wednesday',
  'Thursday',
  'Friday',
  'Saturday',
];

const options = {
  chart: {
// 2- Set the chart type
    type: 'heatmap',
    plotBorderWidth: 1,
  },
  title: {
    text: 'Revenue per hour per weekday heatmap',
  },
  xAxis: {
// 3- Set X-axis value, we need 24h
    min: 0,
    max: 23,
// 4- Set the tickInterval to 1, to show all 24h on X-axis
    tickInterval: 1,
    labels: {
      step: 1,
      style: {
        fontSize: '14px',
        fontFamily: 'Open Sans',
      },
    },
    gridLineWidth: 0,
    lineWidth: 0.5,
    lineColor: 'rgba(0,0,0,0.75)',
    tickWidth: 0.5,
    tickLength: 3,
    tickColor: 'rgba(0,0,0,0.75)',
    title: {
      text: 'Hour',
    },
  },
  yAxis: {
// 5- Set the categories of Y-axis to WEEK_DAYS
    categories: WEEK_DAYS,
    title: 'Weekdays',
    labels: {
      style: {
        fontSize: '14px',
        fontFamily: 'Open Sans',
      },
    },
  },
  tooltip: {
// 6- Show formatted text on hovering over each value in the heatmap
    formatter: function () {
      return (
        '<b>Hour Is: </b>' +
        this.point.x +
        '<br /><b>Day Is:</b> ' +
        this.point.y +
        '<br />' +
        '<b>Revenue Is:</b> $' +
        this.point.value
      );
    },
  },
// 7- Add colors range to the heatmap values
  colorAxis: {
    stops: [
      [0, 'rgba(56, 7, 84, 0.4)'],
      [0.5, 'rgba(56, 7, 84, 0.65)'],
      [1, 'rgba(69, 9, 104, 1)'],
    ],
  },
  series: [
    {
      name: 'Revenue',
      borderWidth: 0.5,
      borderColor: 'white',
      dataLabels: {
        enabled: true,
        color: '#000000',
      },
// 8- Set the values on the heatmap as array [hour, day, value]
      data: [
        [1, 2, 100],
        [4, 3, 200],
        [7, 4, 300],
        [2, 5, 400],
        [5, 6, 500],
        [12, 1, 600],
        [10, 0, 700],
      ],
    },
  ],
};

Clarifying some properties of the options beside the styles properties:

1. Create Y-axis labels WEEK_DAYS.
2. Set the chart type to heatmap.
3. Set X-axis values range, we need 24h.
4. Set the tickInterval to 1, to show all 24h on the X-axis (in case we need to show less hours, we can increase this value to a value less than 23).
5. Set the categories of Y-axis to WEEK_DAYS.
6. Show formatted text on hovering over each value in the heatmap.
7. Add colors range to the heatmap values, the color will be darker for larger values.
8. The data options of the heatmap, accepts an array of arrays, each array can hold 3 values (you can add more), and each value can be defined as the following: [hour, day, value].

---

Now putting all the code together:

import React from 'react';
import Highcharts from 'highcharts';
import HighchartsHeatmap from 'highcharts/modules/heatmap';
import HighchartsReact from 'highcharts-react-official';

HighchartsHeatmap(Highcharts);

const WEEK_DAYS = [
  'Sunday',
  'Monday',
  'Tuesday',
  'Wednesday',
  'Thursday',
  'Friday',
  'Saturday',
];

const options = {
  chart: {
    type: 'heatmap',
    plotBorderWidth: 1,
  },
  title: {
    text: 'Revenue per hour per weekday heatmap',
  },
  xAxis: {
    min: 0,
    max: 23,
    tickInterval: 1,
    labels: {
      step: 1,
      style: {
        fontSize: '14px',
        fontFamily: 'Open Sans',
      },
    },
    gridLineWidth: 0,
    lineWidth: 0.5,
    lineColor: 'rgba(0,0,0,0.75)',
    tickWidth: 0.5,
    tickLength: 3,
    tickColor: 'rgba(0,0,0,0.75)',
    title: {
      text: 'Hour',
    },
  },
  yAxis: {
    categories: WEEK_DAYS,
    title: 'Weekdays',
    labels: {
      style: {
        fontSize: '14px',
        fontFamily: 'Open Sans',
      },
    },
  },
  tooltip: {
    formatter: function () {
      return (
        '<b>Hour Is: </b>' +
        this.point.x +
        '<br /><b>Day Is:</b> ' +
        this.point.y +
        '<br />' +
        '<b>Revenue Is:</b> $' +
        this.point.value
      );
    },
  },
  colorAxis: {
    stops: [
      [0, 'rgba(56, 7, 84, 0.4)'],
      [0.5, 'rgba(56, 7, 84, 0.65)'],
      [1, 'rgba(69, 9, 104, 1)'],
    ],
  },
  series: [
    {
      name: 'Revenue',
      borderWidth: 0.5,
      borderColor: 'white',
      dataLabels: {
        enabled: true,
        color: '#000000',
      },
      data: [
        [1, 2, 100],
        [4, 3, 200],
        [7, 4, 300],
        [2, 5, 400],
        [5, 6, 500],
        [12, 1, 600],
        [10, 0, 700],
      ],
    },
  ],
};

export default function HeatMap() {
  return (
    <div>
      <h1>Heat Map</h1>
      <HighchartsReact highcharts={Highcharts} options={options} />
    </div>
  );
}

And by running the above code into the browser, we will get the following:

---

That’s it for how to implement Heatmaps using HightCharts in React.

Photo from Unsplash.