# 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

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

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

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

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

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

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

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

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

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 *k*th 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 *k*th 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 *k*th 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.

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.

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.

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.

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.

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.

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

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.

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