D3

Power scales ​

Power (“pow”) scales are similar to linear scales, except an exponential transform is applied to the input domain value before the output range value is computed. Each range value y can be expressed as a function of the domain value x: y = mx^k + b, where k is the exponent value. Power scales also support negative domain values, in which case the input value and the resulting output value are multiplied by -1.

scalePow(domain, range) ​

Examples · Source · Constructs a new pow scale with the specified domain and range, the exponent 1, the default interpolator and clamping disabled.

js
const x = d3.scalePow([0, 100], ["red", "blue"]).exponent(2);

If either domain or range are not specified, each defaults to [0, 1].

scaleSqrt(domain, range) ​

Examples · Source · Constructs a new pow scale with the specified domain and range, the exponent 0.5, the default interpolator and clamping disabled.

js
const x = d3.scaleSqrt([0, 100], ["red", "blue"]);

If either domain or range are not specified, each defaults to [0, 1]. This is a convenience method equivalent to d3.scalePow(…).exponent(0.5).

pow.exponent(exponent) ​

Examples · Source · If exponent is specified, sets the current exponent to the given numeric value and returns this scale.

js
const x = d3.scalePow([0, 100], ["red", "blue"]).exponent(2);

If exponent is not specified, returns the current exponent, which defaults to 1.

js
x.exponent() // 2

If the exponent is 1, the pow scale is effectively a linear scale.