Shuffle a numpy array

Question

I have a 2-d numpy array that I would like to shuffle. Is the best way to reshape it to 1-d, shuffle and reshape again to 2-d or is it possible to shuffle without reshaping?

Answer 1

I think this is very important to note.
You can use random.shuffle(a) if a is 1-D numpy array. If it is N-D (where N > 2) than

random.shuffle(a)

will spoil your data and return some random thing. As you can see here:

import random
import numpy as np
a=np.arange(9).reshape((3,3))
random.shuffle(a)
print a

[[0 1 2]
 [3 4 5]
 [3 4 5]]

This is a known bug (or feature?) of numpy.

So, use only numpy.random.shuffle(a) for numpy arrays.