Numpy随机选择元组

Question

I'm having trouble to create an array of random choices, where a choice is a tuple.

I get the error: a must be 1-dimensional

Here is an example:

choices = ((0,0,0),(255,255,255))
numpy.random.choice(choices,4)

Is there any other way to do this?

Expected result:

a numpy array consiting of 4 elements randomly picked from the choices tuple.

((0,0,0),(0,0,0),(255,255,255),(255,255,255))

Answer 1

Use choice to choose the 1dim indices into the array, then index it.

In the example you provided, only the number of possible choices affects the nature of the choice, not the actual values (0, 255). Choosing indices is the 1dim problem choice knows how to handle.

choices = numpy.array([[0,0,0],[255,255,255]])
idx = numpy.random.choice(len(choices),4)
choices[idx]

Answer 2

Just adding this answer to provide a non-numpy based answer:

choices = ((0,0,0),(255,255,255))

from random import choice

print tuple(choice(choices) for _ in range(4))

Answer 3

If you want to specifically sample without replacement, you can try:

import random
choices = ((0,0,0),(1,1,1),(2,2,2),(3,3,3))
random.sample(choices, 2)