canvas-heatmap

Canvas Heatmap

Interactive heatmap, capable of displaying 1,000,000+ data points using canvas and d3.

Uses d3 for rendering the axis.

Check out the examples:

• Basic (source)

Quick start

import heatmap from 'canvas-heatmap';

then

heatmap(div, data, options={});

or

<script type="text/javascript" src="https://unpkg.com/canvas-heatmap"></script>

then

heatmap(div, data, options={});

API reference

div

The unique id of a div. The graph will be appended to this div.

data

Data can be an object {x: [], y:[], z:[[]]} or and array of objects [{},{}].

Parameter	Description
x	1D array of x coordinates
y	1D array of y coordinates
z	2D array of z values (z.shape === (y.shape, x.shape))

options

Option	Description	Default	Type
title	Title for the graph (hidden for web display)		String
xLabel	Label for the x axis		String
yLabel	Label for the y axis		String
zLabel	Label for the z axis		String
xUnit	Unit for the x axis		String
yUnit	Unit for the y axis		String
zUnit	Unit for the z axis		String
xLog	Use log scale for the x axis	false	Boolean
yLog	Use log scale for the y axis	false	Boolean
tooltip	Show a tooltip on hover	true	Boolean
zMin	Minimum value for z color scale	Data min	Number
zMax	Maximum value for z color scale	Data max	Number
fontSize	Font size of graph text	12	Number
contour	Draw filled contours	false	Boolean
yReverse	Reverse y axis	false	Boolean
xReverse	Reverse x axis	false	Boolean
marginTop	Top margin in px	10	Number
marginLeft	Left margin in px	46	Number
marginBottom	Bottom margin in px	46	Number
marginRight	Right margin in px	70	Number
legendRight	Plot the legend	true	Boolean
thresholdStep	Number of thersholds for when plotting contours	20	Number
backgroundColor	Background color in html	transparent	String
autoDownsample	Downsample for contour plot	500	Number
setDownloadGraph	Add png download to function	false	Function
setDownloadGraphDiv	Unique div ID to apply onclick event for png download	false	String
hover	Return the mouse values	false	Function
width	Width of the graph	div width	Number
height	Height of the graph	div height	Number
colors	Color range for the plot (see below for example)	Red -> Blue	Array

Colors

Example of color range:

[
    { color: "#000000", point: 0.0 },
    { color: "#550088", point: 0.14285714285714285 },
    { color: "#0000ff", point: 0.2857142857142857 },
    { color: "#00ffff", point: 0.42857142857142855 },
    { color: "#00ff00", point: 0.5714285714285714 },
    { color: "#ffff00", point: 0.7142857142857143 },
    { color: "#ff8c00", point: 0.8571428571428571 },
    { color: "#ff0000", point: 1.0 },
];