Releases · d3/d3-scale

First stable release.
Fix order of ticks with log scales with huge descending domains.
Add sequential.interpolator.

Changes since D3 3.x

Pursuant to the great namespace flattening:

d3.scale.linear ↦ d3.scaleLinear
d3.scale.sqrt ↦ d3.scaleSqrt
d3.scale.pow ↦ d3.scalePow
d3.scale.log ↦ d3.scaleLog
d3.scale.quantize ↦ d3.scaleQuantize
d3.scale.threshold ↦ d3.scaleThreshold
d3.scale.quantile ↦ d3.scaleQuantile
d3.scale.identity ↦ d3.scaleIdentity
d3.scale.ordinal ↦ d3.scaleOrdinal
d3.time.scale ↦ d3.scaleTime
d3.time.scale.utc ↦ d3.scaleUtc

Scales now generate ticks in the same order as the domain: if you have a descending domain, you now get descending ticks. This change affects the order of tick elements generated by axes. For example:

d3.scaleLinear().domain([10, 0]).ticks(5); // [10, 8, 6, 4, 2, 0]

Log tick formatting now assumes a default count of ten, not Infinity, if not specified. Log scales with domains that span many powers (such as from 1e+3 to 1e+29) now return only one tick per power rather than returning base ticks per power. Non-linear quantitative scales are slightly more accurate.

You can now control whether an ordinal scale’s domain is implicitly extended when the scale is passed a value that is not already in its domain. By default, ordinal.unknown is d3.scaleImplicit, causing unknown values to be added to the domain:

var x = d3.scaleOrdinal()
    .domain([0, 1])
    .range(["red", "green", "blue"]);

x.domain(); // [0, 1]
x(2); // "blue"
x.domain(); // [0, 1, 2]

By setting ordinal.unknown, you instead define the output value for unknown inputs. This is particularly useful for choropleth maps where you want to assign a color to missing data.

var x = d3.scaleOrdinal()
    .domain([0, 1])
    .range(["red", "green", "blue"])
    .unknown(undefined);

x.domain(); // [0, 1]
x(2); // undefined
x.domain(); // [0, 1]

The ordinal.rangeBands and ordinal.rangeRoundBands methods have been replaced with a new subclass of ordinal scale: band scales. The following code in 3.x:

var x = d3.scaleOrdinal()
    .domain(["a", "b", "c"])
    .rangeBands([0, width]);

Is equivalent to this in 4.0:

var x = d3.scaleBand()
    .domain(["a", "b", "c"])
    .range([0, width]);

The new band.padding, band.paddingInner and band.paddingOuter methods replace the optional arguments to ordinal.rangeBands. The new band.bandwidth and band.step methods replace ordinal.rangeBand. There’s also a new band.align method which you can use to control how the extra space outside the bands is distributed, say to shift columns closer to the y-axis.

Similarly, the ordinal.rangePoints and ordinal.rangeRoundPoints methods have been replaced with a new subclass of ordinal scale: point scales. The following code in 3.x:

var x = d3.scaleOrdinal()
    .domain(["a", "b", "c"])
    .rangePoints([0, width]);

Is equivalent to this in 4.0:

var x = d3.scalePoint()
    .domain(["a", "b", "c"])
    .range([0, width]);

The new point.padding method replaces the optional padding argument to ordinal.rangePoints. Like ordinal.rangeBand with ordinal.rangePoints, the point.bandwidth method always returns zero; a new point.step method returns the interval between adjacent points.

The ordinal scale constructor now takes an optional range for a shorter alternative to ordinal.range. This is especially useful now that the categorical color scales have been changed to simple arrays of colors rather than specialized ordinal scale constructors:

d3.scale.category10 ↦ d3.schemeCategory10
d3.scale.category20 ↦ d3.schemeCategory20
d3.scale.category20b ↦ d3.schemeCategory20b
d3.scale.category20c ↦ d3.schemeCategory20c

The following code in 3.x:

var color = d3.scaleCategory10();

Is equivalent to this in 4.0:

var color = d3.scaleOrdinal(d3.schemeCategory10);

Sequential scales, are a new class of scales with a fixed output interpolator instead of a range. Typically these scales are used to implement continuous sequential or diverging color schemes. Inspired by Matplotlib’s new perceptually-motived colormaps, 4.0 now features viridis, inferno, magma, plasma interpolators for use with sequential scales. Using d3.quantize, these interpolators can also be applied to quantile, quantize and threshold scales.