Installing Necessary Libraries

To create an Area Difference Chart, you need to install several modules from the Visx library. Execute the following command in your terminal:

npm install @visx/axis @visx/curve @visx/grid @visx/group @visx/mock-data @visx/responsive @visx/scale @visx/shape @visx/threshold

Creating the Area Difference Chart

After installing the required libraries, we can proceed to create the chart with the following code:

import React from "react";

import { Group } from "@visx/group";

import { curveBasis } from "@visx/curve";

import { LinePath } from "@visx/shape";

import { Threshold } from "@visx/threshold";

import { scaleTime, scaleLinear } from "@visx/scale";

import { AxisLeft, AxisBottom } from "@visx/axis";

import { GridRows, GridColumns } from "@visx/grid";

import cityTemperature from "@visx/mock-data/lib/mocks/cityTemperature";

export const background = "#f3f3f3";

const date = (d) => new Date(d.date).valueOf();

const ny = (d) => Number(d["New York"]);

const sf = (d) => Number(d["San Francisco"]);

const timeScale = scaleTime({

domain: [

Math.min(...cityTemperature.map(date)),

Math.max(...cityTemperature.map(date))

]

});

const temperatureScale = scaleLinear({

domain: [

Math.min(...cityTemperature.map((d) => Math.min(ny(d), sf(d)))),

Math.max(...cityTemperature.map((d) => Math.max(ny(d), sf(d))))

],

nice: true

});

const defaultMargin = { top: 40, right: 30, bottom: 50, left: 40 };

function ThresholdComponent({ width, height, margin = defaultMargin }) {

if (width < 10) return null;

const xMax = width - margin.left - margin.right;

const yMax = height - margin.top - margin.bottom;

timeScale.range([0, xMax]);

temperatureScale.range([yMax, 0]);

return (

<svg width={width} height={height}>

<rect width={width} height={height} fill={background} />

<Group top={margin.top} left={margin.left}>

<GridRows scale={temperatureScale} width={xMax} />

<GridColumns scale={timeScale} height={yMax} />

<Threshold

data={cityTemperature}

x={(d) => timeScale(date(d)) ?? 0}

y0={(d) => temperatureScale(ny(d)) ?? 0}

y1={(d) => temperatureScale(sf(d)) ?? 0}

clipAboveTo={0}

clipBelowTo={yMax}

curve={curveBasis}

belowAreaProps={{

fill: "violet",

fillOpacity: 0.4

}}

aboveAreaProps={{

fill: "green",

fillOpacity: 0.4

}}

/>

<LinePath

data={cityTemperature}

x={(d) => timeScale(date(d)) ?? 0}

y={(d) => temperatureScale(sf(d)) ?? 0}

stroke="#222"

strokeWidth={1.5}

strokeOpacity={0.8}

strokeDasharray="1,2"

/>

<LinePath

data={cityTemperature}

x={(d) => timeScale(date(d)) ?? 0}

y={(d) => temperatureScale(ny(d)) ?? 0}

stroke="#222"

strokeWidth={1.5}

/>

</Group>

</svg>

);

}

export default function App() {

return (

<div>

<ThresholdComponent width={800} height={400} />

</div>

);

}

This code utilizes mock data from the Visx library to generate the chart. We define the timeScale for the x-axis and the temperatureScale for the y-axis, allowing us to effectively visualize the data.

The ThresholdComponent is where the area difference chart is constructed. It calculates the maximum x and y values to set up the axes and renders the necessary SVG elements, including rectangles, grid lines, and the area paths.

The first video titled "Pie Charts in React with visx - YouTube" demonstrates how to create pie charts using the Visx library, providing valuable insights into visualization techniques.

The second video, "Chart.js in React.js tutorial: Create a great looking area chart," offers tips on customizing area charts, enhancing your knowledge of visual data representation.