d3-scale-chromatic

What is d3-scale-chromatic?

The d3-scale-chromatic package provides color schemes designed to work with d3-scale's sequential, diverging, and categorical color scales. It includes a variety of color palettes that can be used for data visualization, such as for mapping data values to colors in charts and graphs.

What are d3-scale-chromatic's main functionalities?

Sequential Color Schemes

Sequential color schemes are ideal for displaying ordered data that progresses from low to high. The package provides a variety of single-hue and multi-hue color schemes.

import { scaleSequential } from 'd3-scale';
import { interpolateBlues } from 'd3-scale-chromatic';

const colorScale = scaleSequential(interpolateBlues).domain([0, 100]);
console.log(colorScale(50)); // Outputs a color from the 'Blues' sequential color scheme

Diverging Color Schemes

Diverging color schemes are used to visualize data that diverges from a median value, with contrasting colors on either side. This is useful for highlighting deviation from a midpoint.

import { scaleDiverging } from 'd3-scale';
import { interpolatePiYG } from 'd3-scale-chromatic';

const colorScale = scaleDiverging(interpolatePiYG).domain([0, 50, 100]);
console.log(colorScale(50)); // Outputs the middle color from the 'PiYG' diverging color scheme

Categorical Color Schemes

Categorical color schemes are used for discrete data that falls into distinct categories. The package provides several categorical color palettes with a fixed number of colors.

import { scaleOrdinal } from 'd3-scale';
import { schemeCategory10 } from 'd3-scale-chromatic';

const colorScale = scaleOrdinal(schemeCategory10);
console.log(colorScale('category1')); // Outputs a color from the 'Category10' categorical color scheme

Other packages similar to d3-scale-chromatic

chroma-js

Chroma.js is a powerful library for all kinds of color conversions and color scales. It offers similar functionalities to d3-scale-chromatic but with additional features like color manipulation, blending, and more complex color scale generation.

colorbrewer

ColorBrewer is an original source of some of the color schemes found in d3-scale-chromatic. It provides a set of color palettes for cartography, which can be used independently of D3. However, it does not offer the same level of integration with D3's scale functions.

palette.js

Palette.js is a smaller library that can generate color palettes for data visualization. It is not as comprehensive as d3-scale-chromatic and lacks the direct integration with D3's scale functions.

README

d3-scale-chromatic

This module provides sequential, diverging and categorical color schemes designed to work with d3-scale’s d3.scaleOrdinal and d3.scaleSequential. Most of these schemes are derived from Cynthia A. Brewer’s ColorBrewer. Since ColorBrewer publishes only discrete color schemes, the sequential and diverging scales are interpolated using uniform B-splines.

For example, to create a categorical color scale using the Accent color scheme:

var accent = d3.scaleOrdinal(d3.schemeAccent);

To create a sequential discrete nine-color scale using the Blues color scheme:

var blues = d3.scaleOrdinal(d3.schemeBlues[9]);

To create a diverging, continuous color scale using the PiYG color scheme:

var piyg = d3.scaleSequential(d3.interpolatePiYG);

Installing

If you use NPM, npm install d3-scale-chromatic. Otherwise, download the latest release or load directly from d3js.org as a standalone library. AMD, CommonJS, and vanilla environments are supported. In vanilla, a d3 global is exported:

<script src="https://d3js.org/d3-color.v1.min.js"></script>
<script src="https://d3js.org/d3-interpolate.v1.min.js"></script>
<script src="https://d3js.org/d3-scale-chromatic.v1.min.js"></script>
<script>

var yellow = d3.interpolateYlGn(0), // "rgb(255, 255, 229)"
    yellowGreen = d3.interpolateYlGn(0.5), // "rgb(120, 197, 120)"
    green = d3.interpolateYlGn(1); // "rgb(0, 69, 41)"

</script>

Or, as part of the D3 default bundle:

<script src="https://d3js.org/d3.v5.min.js"></script>
<script>

var yellow = d3.interpolateYlGn(0), // "rgb(255, 255, 229)"
    yellowGreen = d3.interpolateYlGn(0.5), // "rgb(120, 197, 120)"
    green = d3.interpolateYlGn(1); // "rgb(0, 69, 41)"

</script>

Try d3-scale-chromatic in your browser.

API Reference

Categorical

# d3.schemeCategory10 <>

An array of ten categorical colors represented as RGB hexadecimal strings.

# d3.schemeAccent <>

An array of eight categorical colors represented as RGB hexadecimal strings.

# d3.schemeDark2 <>

An array of eight categorical colors represented as RGB hexadecimal strings.

# d3.schemePaired <>

An array of twelve categorical colors represented as RGB hexadecimal strings.

# d3.schemePastel1 <>

An array of nine categorical colors represented as RGB hexadecimal strings.

# d3.schemePastel2 <>

An array of eight categorical colors represented as RGB hexadecimal strings.

# d3.schemeSet1 <>

An array of nine categorical colors represented as RGB hexadecimal strings.

# d3.schemeSet2 <>

An array of eight categorical colors represented as RGB hexadecimal strings.

# d3.schemeSet3 <>

An array of twelve categorical colors represented as RGB hexadecimal strings.

Diverging

Diverging color schemes are available as continuous interpolators (often used with d3.scaleSequential) and as discrete schemes (often used with d3.scaleOrdinal). Each discrete scheme, such as d3.schemeBrBG, is represented as an array of arrays of hexadecimal color strings. The kth element of this array contains the color scheme of size k; for example, d3.schemeBrBG[9] contains an array of nine strings representing the nine colors of the brown-blue-green diverging color scheme. Diverging color schemes support a size k ranging from 3 to 11.

# d3.interpolateBrBG(t) <>
# d3.schemeBrBG[k]

Given a number t in the range [0,1], returns the corresponding color from the “BrBG” diverging color scheme represented as an RGB string.

# d3.interpolatePRGn(t) <>
# d3.schemePRGn[k]

Given a number t in the range [0,1], returns the corresponding color from the “PRGn” diverging color scheme represented as an RGB string.

# d3.interpolatePiYG(t) <>
# d3.schemePiYG[k]

Given a number t in the range [0,1], returns the corresponding color from the “PiYG” diverging color scheme represented as an RGB string.

# d3.interpolatePuOr(t) <>
# d3.schemePuOr[k]

Given a number t in the range [0,1], returns the corresponding color from the “PuOr” diverging color scheme represented as an RGB string.

# d3.interpolateRdBu(t) <>
# d3.schemeRdBu[k]

Given a number t in the range [0,1], returns the corresponding color from the “RdBu” diverging color scheme represented as an RGB string.

# d3.interpolateRdGy(t) <>
# d3.schemeRdGy[k]

Given a number t in the range [0,1], returns the corresponding color from the “RdGy” diverging color scheme represented as an RGB string.

# d3.interpolateRdYlBu(t) <>
# d3.schemeRdYlBu[k]

Given a number t in the range [0,1], returns the corresponding color from the “RdYlBu” diverging color scheme represented as an RGB string.

# d3.interpolateRdYlGn(t) <>
# d3.schemeRdYlGn[k]

Given a number t in the range [0,1], returns the corresponding color from the “RdYlGn” diverging color scheme represented as an RGB string.

# d3.interpolateSpectral(t) <>
# d3.schemeSpectral[k]

Given a number t in the range [0,1], returns the corresponding color from the “Spectral” diverging color scheme represented as an RGB string.

Sequential (Single Hue)

Sequential, single-hue color schemes are available as continuous interpolators (often used with d3.scaleSequential) and as discrete schemes (often used with d3.scaleOrdinal). Each discrete scheme, such as d3.schemeBlues, is represented as an array of arrays of hexadecimal color strings. The kth element of this array contains the color scheme of size k; for example, d3.schemeBlues[9] contains an array of nine strings representing the nine colors of the blue sequential color scheme. Sequential, single-hue color schemes support a size k ranging from 3 to 9.

# d3.interpolateBlues(t) <>
# d3.schemeBlues[k]

Given a number t in the range [0,1], returns the corresponding color from the “Blues” sequential color scheme represented as an RGB string.

# d3.interpolateGreens(t) <>
# d3.schemeGreens[k]

Given a number t in the range [0,1], returns the corresponding color from the “Greens” sequential color scheme represented as an RGB string.

# d3.interpolateGreys(t) <>
# d3.schemeGreys[k]

Given a number t in the range [0,1], returns the corresponding color from the “Greys” sequential color scheme represented as an RGB string.

# d3.interpolateOranges(t) <>
# d3.schemeOranges[k]

Given a number t in the range [0,1], returns the corresponding color from the “Oranges” sequential color scheme represented as an RGB string.

# d3.interpolatePurples(t) <>
# d3.schemePurples[k]

Given a number t in the range [0,1], returns the corresponding color from the “Purples” sequential color scheme represented as an RGB string.

# d3.interpolateReds(t) <>
# d3.schemeReds[k]

Given a number t in the range [0,1], returns the corresponding color from the “Reds” sequential color scheme represented as an RGB string.

Sequential (Multi-Hue)

Sequential, multi-hue color schemes are available as continuous interpolators (often used with d3.scaleSequential) and as discrete schemes (often used with d3.scaleOrdinal). Each discrete scheme, such as d3.schemeBuGn, is represented as an array of arrays of hexadecimal color strings. The kth element of this array contains the color scheme of size k; for example, d3.schemeBuGn[9] contains an array of nine strings representing the nine colors of the blue-green sequential color scheme. Sequential, multi-hue color schemes support a size k ranging from 3 to 9.

# d3.interpolateViridis(t) <>

Given a number t in the range [0,1], returns the corresponding color from the “viridis” perceptually-uniform color scheme designed by van der Walt, Smith and Firing for matplotlib, represented as an RGB string.

# d3.interpolateInferno(t) <>

Given a number t in the range [0,1], returns the corresponding color from the “inferno” perceptually-uniform color scheme designed by van der Walt and Smith for matplotlib, represented as an RGB string.

# d3.interpolateMagma(t) <>

Given a number t in the range [0,1], returns the corresponding color from the “magma” perceptually-uniform color scheme designed by van der Walt and Smith for matplotlib, represented as an RGB string.

# d3.interpolatePlasma(t) <>

Given a number t in the range [0,1], returns the corresponding color from the “plasma” perceptually-uniform color scheme designed by van der Walt and Smith for matplotlib, represented as an RGB string.

# d3.interpolateWarm(t) <>

Given a number t in the range [0,1], returns the corresponding color from a 180° rotation of Niccoli’s perceptual rainbow, represented as an RGB string.

# d3.interpolateCool(t) <>

Given a number t in the range [0,1], returns the corresponding color from Niccoli’s perceptual rainbow, represented as an RGB string.

# d3.interpolateCubehelixDefault(t) <>

Given a number t in the range [0,1], returns the corresponding color from Green’s default Cubehelix represented as an RGB string.

# d3.interpolateBuGn(t) <>
# d3.schemeBuGn[k]

Given a number t in the range [0,1], returns the corresponding color from the “BuGn” sequential color scheme represented as an RGB string.

# d3.interpolateBuPu(t) <>
# d3.schemeBuPu[k]

Given a number t in the range [0,1], returns the corresponding color from the “BuPu” sequential color scheme represented as an RGB string.

# d3.interpolateGnBu(t) <>
# d3.schemeGnBu[k]

Given a number t in the range [0,1], returns the corresponding color from the “GnBu” sequential color scheme represented as an RGB string.

# d3.interpolateOrRd(t) <>
# d3.schemeOrRd[k]

Given a number t in the range [0,1], returns the corresponding color from the “OrRd” sequential color scheme represented as an RGB string.

# d3.interpolatePuBuGn(t) <>
# d3.schemePuBuGn[k]

Given a number t in the range [0,1], returns the corresponding color from the “PuBuGn” sequential color scheme represented as an RGB string.

# d3.interpolatePuBu(t) <>
# d3.schemePuBu[k]

Given a number t in the range [0,1], returns the corresponding color from the “PuBu” sequential color scheme represented as an RGB string.

# d3.interpolatePuRd(t) <>
# d3.schemePuRd[k]

Given a number t in the range [0,1], returns the corresponding color from the “PuRd” sequential color scheme represented as an RGB string.

# d3.interpolateRdPu(t) <>
# d3.schemeRdPu[k]

Given a number t in the range [0,1], returns the corresponding color from the “RdPu” sequential color scheme represented as an RGB string.

# d3.interpolateYlGnBu(t) <>
# d3.schemeYlGnBu[k]

Given a number t in the range [0,1], returns the corresponding color from the “YlGnBu” sequential color scheme represented as an RGB string.

# d3.interpolateYlGn(t) <>
# d3.schemeYlGn[k]

Given a number t in the range [0,1], returns the corresponding color from the “YlGn” sequential color scheme represented as an RGB string.

# d3.interpolateYlOrBr(t) <>
# d3.schemeYlOrBr[k]

Given a number t in the range [0,1], returns the corresponding color from the “YlOrBr” sequential color scheme represented as an RGB string.

# d3.interpolateYlOrRd(t) <>
# d3.schemeYlOrRd[k]

Given a number t in the range [0,1], returns the corresponding color from the “YlOrRd” sequential color scheme represented as an RGB string.

Cyclical

# d3.interpolateRainbow(t) <>

Given a number t in the range [0,1], returns the corresponding color from d3.interpolateWarm scale from [0.0, 0.5] followed by the d3.interpolateCool scale from [0.5, 1.0], thus implementing the cyclical less-angry rainbow color scheme.

# d3.interpolateSinebow(t) <>

Given a number t in the range [0,1], returns the corresponding color from the “sinebow” color scheme by Jim Bumgardner and Charlie Loyd.