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stonewise-d3-scale

1.0.0 • Public • Published

@visx/scale

Installation

`npm install --save @visx/scale`

Overview of scales

The `@visx/scale` package aims to provide a wrapper around existing `d3` scaling originally defined in the d3-scale package.

Scales are functions that help you map your data values to the physical pixel size that your graph requires. For example, let's say you wanted to create a bar chart to show populations per country. If you were to use a 1-to-1 scale (IE: 1 pixel per y value) your bar for the USA would be about 321.4 million pixels high!

Instead, you can tell `visx` a function to use that takes a data value (like your population per country) and quantitatively maps to another dimensional space, like pixels.

For example, we could create a linear scale like this:

```const graphWidth = 500;
const graphHeight = 200;
const [minX, maxX] = getXMinAndMax();
const [minY, maxY] = getYMinAndMax();

const xScale = Scale.scaleLinear({
domain: [minX, maxX], // x-coordinate data values
range: [0, graphWidth], // svg x-coordinates, svg x-coordinates increase left to right
round: true,
});

const yScale = Scale.scaleLinear({
domain: [minY, maxY], // y-coordinate data values
// svg y-coordinates, these increase from top to bottom so we reverse the order
// so that minY in data space maps to graphHeight in svg y-coordinate space
range: [graphHeight, 0],
round: true,
});

// ...

const points = data.map((d, i) => {
const barHeight = graphHeight - yScale(d.y);
return <Shape.Bar height={barHeight} y={graphHeight - barHeight} />;
});```

Different types of scales

Band scale

Original d3 docs

Example:

```const scale = Scale.scaleBand({
/*
range,
round,
domain,
nice = false
*/
});```

Linear scale

Original d3 docs

Example:

```const scale = Scale.scaleLinear({
/*
range,
round,
domain,
nice = false,
clamp = false,
*/
});```

Log scale

Original d3 docs

Example:

```const scale = Scale.scaleLog({
/*
range,
round,
domain,
base,
nice = false,
clamp = false,
*/
});```

Original d3 docs

Example:

```const scale = Scale.scaleRadial({
/*
range,
round,
domain,
nice = false,
clamp = false,
*/
});```

Ordinal scale

Original d3 docs

Example:

```const scale = Scale.scaleOrdinal({
/*
range,
domain,
unknown,
*/
});```

Point scale

Original d3 docs

Example:

```const scale = Scale.scalePoint({
/*
range,
round,
domain,
align,
nice = false,
*/
});```

Power scale

Original d3 docs

Example:

```const scale = Scale.scalePower({
/*
range,
round,
domain,
exponent,
nice = false,
clamp = false,
*/
});```

Square Root scale

Original d3 docs

Example:

```// No need to set the exponent, It is always 0.5
const scale = Scale.scaleSqrt({
/*
range,
round,
domain,
nice = false,
clamp = false,
*/
});```

Time scale

Original d3 docs

Example:

```const scale = Scale.scaleTime({
/*
range,
round,
domain,
nice = false,
clamp = false,
*/
});```

You also can scale time with Coordinated Universal Time via `scaleUtc`.

Example:

```const scale = Scale.scaleUtc({
/*
range,
round,
domain,
nice = false,
clamp = false,
*/
});```

Color Scales

D3 scales offer the ability to map points to colors. You can use `d3-scale-chromatic` in conjunction with visx's `scaleOrdinal` to make color scales.

You can install `d3-scale-chromatic` with npm:

`npm install --save d3-scale-chromatic`

You create a color scale like so:

```import { scaleOrdinal } from '@visx/scale';
import { schemeSet1 } from 'd3-scale-chromatic';

const colorScale = scaleOrdinal({
domain: arrayOfThings,
range: schemeSet1,
});```

This generates a color scale with the following colors:

There are a number of other categorical color schemes available, along with other continuous color schemes.

Keywords

Install

`npm i stonewise-d3-scale`

Repository

github.com/airbnb/visx

1

1.0.0

MIT

105 kB

137