rand.py 文件源码

def sample_sphere3d(radius=1., n_samples=1):
    """
    Sample points from 3D sphere.

    @param radius: radius of the sphere
    @type radius: float

    @param n_samples: number of samples to return
    @type n_samples: int

    @return: n_samples times random cartesian coordinates inside the sphere
    @rtype: numpy array
    """
    from numpy.random  import random
    from numpy import arccos, transpose, cos, sin, pi, power

    r = radius * power(random(n_samples), 1 / 3.)
    theta = arccos(2. * (random(n_samples) - 0.5))
    phi = 2 * pi * random(n_samples)

    x = cos(phi) * sin(theta) * r
    y = sin(phi) * sin(theta) * r
    z = cos(theta) * r

    return transpose([x, y, z])