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.

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.

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.

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

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

x.exponent() // 2

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