sterlingwes / randomcolor

Javascript module for generating random, distinguishable, pleasing colors (ie: for chart series).

Random Color

Random color is a simple javascript module for generating random colors that contrast enough to distinguish between one another, and are not too loud (by default, all colours can have readable black/dark font overlayed).

Example

Useful, for example, in charts and diagrams where X number of series need to be distinguished by color.

See changelog.

Getting it

Node.js

npm install rcolor

Browser

Clone this repo / copy dist/rcolor.min.js

Note that the dist/rcolor.js file is a CommonJS export (the node.js build)

Using it

With the browser build:

window.rcolor()
// > "#79f2ab"

With the node build:

const rcolor = require('rcolor')
rcolor() // "#79f2ab"

This module holds the initial random number seed as internal state. To regenerate the random number seed, call the reSeed method: rcolor.reSeed().

Options / Configuration

You can specify the hue, saturation and value. The following are the defaults:

const goldenRatio = 0.618 // ... truncated

rcolor({
  hue: (Math.random() + goldenRatio) % 1,
  saturation: 0.5,
  value: 0.95
})

Pre-v1.0

If you used this module prior to NPM availability (between 2013 and 2017), you can find that source (including the Dart version) on the legacy branch.

License

Free to use and distribute under the MIT license.

Sorry, Colour

Apologies in advance to my commonwealth friends, if you find 'color' vs. 'colour'. It was a hard decision for a Canadian. :)

Wes Johnson @SterlingWes

randomcolor's Issues

Initial Seed & Color by Id

Two things that were missing for me in this script. This states it's useful for charts and diagrams, but while you may want random distinct colors, you often want them to be the same random colors each time the page is loaded. So it would be nice to have an initial seed value, instead of a Random value based on system time. Perhaps something like this:

var RColor = function(seed) {
    this.hue            = seed || Math.random(),
    this.goldenRatio    = 0.618033988749895;
    this.hexwidth       = 2;
};

Secondly, I often have Id's set to particular sets of data. Group 1 gets one color, Group 2 another, etc. So it would be nice to allow it to get that same random color given an Id. Perhaps something like this, after setting this up in the initialization.

this.initialhue = this.hue;

RColor.prototype.getById = function(id,hex,saturation,value) {
    if (id % 1 !== 0) return this.get(hex,saturation,value);
    hueval = this.initialhue;
    hueval += this.goldenRatio * id;
    hueval %= 1;
    if(typeof saturation !== "number")  saturation = 0.5;
    if(typeof value !== "number")       value = 0.95;
    var rgb = this.hsvToRgb(this.hue,saturation,value);
    if(hex)
        return "#" +  this.padHex(rgb[0].toString(16))
                    + this.padHex(rgb[1].toString(16))
                    + this.padHex(rgb[2].toString(16));
    else
        return rgb;
};

RColor is not defined

probably just me but might help someone else.
So i imported the rcolor.js into my node project but when i call

var color = new RColor;
var c2 = color.get(true);

i get a fatal error that breaks my program

RColor is not defined

the rcolor.js is in the same directory as the function I'm calling, so its not a nesting issue it just doesn't reconize it.

Color proximity

This library often generates colours that are too close in proximity to others in a series. Should add some maths to account for this and ensure a certain amount of differentiation within a certain sample size.

For reference: http://www.brucelindbloom.com/index.html?Equations.html

Hex color literals need zero-padding.

Problem: using an HSV Value < 2 results in color literals with less than six hex digits (e.g. "#19177", because toString(16) doesn't pad left with zeros. These values are ignored by CSS,

I offer a method here that corrects this problem:

RColor.prototype.byteToHex = function(number) {
    var size = 2; // minimum string length, padded left with zeros
    var numStr = number.toString(16);
    while (numStr.length < size) numStr = "0" + numStr;
    return numStr;
};

Then, in RColor.prototype.get():

    if(hex)
        return = "#" + this.byteToHex(rgb[0])
                         + this.byteToHex(rgb[1])
                         + this.byteToHex(rgb[2]);

Thanks. This project is very useful and well-crafted.