Math

Math

API Reference ▸ Core ▸ Math

Pseudorandom Number Generation

You can use the built-in Math.random to generate uniform distributions. For example, to generate a random integer between 0 and 99 (inclusive), you can say Math.floor(Math.random() * 100).

d3.random.normal([mean, [deviation]])

Returns a function for generating random numbers with a normal (Gaussian) distribution. The expected value of the generated pseudorandom numbers is mean, with the given standard deviation. If deviation is not specified, it defaults to 1.0; if mean is not specified, it defaults to 0.0.

d3.random.logNormal([mean, [deviation]])

Returns a function for generating random numbers with a log-normal distribution. The expected value of the random variable’s natural logrithm is mean, with the given standard deviation. If deviation is not specified, it defaults to 1.0; if mean is not specified, it defaults to 0.0.

d3.random.bates(count)

Returns a function for generating random numbers with a Bates distribution. The number of independent variables is specified by count.

d3.random.irwinHall(count)

Returns a function for generating random numbers with an Irwin–Hall distribution. The number of independent variables is specified by count.

2D Transforms

d3.transform(string)

Parses the given 2D affine transform string, as defined by SVG's transform attribute. The transform is then decomposed to an object with fields for translate, rotate, x-skew and scale. This behavior is standardized by CSS: see matrix decomposition for animation.

transform.rotate

Returns the rotation angle θ of this transform, in degrees.

transform.translate

Returns the [dx, dy] translation of this transform, as a two-element array in local coordinates (typically pixels).

transform.skew

Returns the x-skew φ of this transform, in degrees.

transform.scale

Returns the [kx, ky] scale of this transform, as a two-element array.

transform.toString()

Returns a string representation of this transform, in the form "translate(dx,dy)rotate(θ)skewX(φ)scale(kx,ky)".