continuous.interpolate(interpolate)
If interpolate is specified, sets the scale’s range interpolator factory. This interpolator factory is used to create interpolators for each adjacent pair of values from the range; these interpolators then map a normalized domain parameter t in [0, 1] to the corresponding value in the range. If factory is not specified, returns the scale’s current interpolator factory, which defaults to interpolate. See d3-interpolate for more interpolators.
For example, consider a diverging color scale with three colors in the range:
1 2 3 | var color = d3.scaleLinear() .domain([-100, 0, +100]) .range(["red", "white", "green"]); |
Two interpolators are created internally by the scale, equivalent to:
1 2 | var i0 = d3.interpolate("red", "white"), i1 = d3.interpolate("white", "green"); |
A common reason to specify a custom interpolator is to change the color space of interpolation. For example, to use HCL:
1 2 3 4 | var color = d3.scaleLinear() .domain([10, 100]) .range(["brown", "steelblue"]) .interpolate(d3.interpolateHcl); |
Or for Cubehelix with a custom gamma:
1 2 3 4 | var color = d3.scaleLinear() .domain([10, 100]) .range(["brown", "steelblue"]) .interpolate(d3.interpolateCubehelix.gamma(3)); |
Note: the default interpolator may reuse return values. For example, if the range values are objects, then the value interpolator always returns the same object, modifying it in-place. If the scale is used to set an attribute or style, this is typically acceptable (and desirable for performance); however, if you need to store the scale’s return value, you must specify your own interpolator or make a copy as appropriate.
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