CODEWITHSUNDEEP
pythonarraysnumpy
bluevoxel
bluevoxel

Reputation: 5378

How to draw N elements of random indices from numpy array without repetition?

Say, I have a numpy array defined as:

X = numpy.array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

Now I want to draw 3 elements from this array, but with random indices and without repetition, so I'll get, say:

X_random_draw = numpy.array([5, 0, 9]

How can I achieve something like this with the least effort and with the greatest performance speed? Thank you in advance.

Upvotes: 3

Views: 3658

Answers (1)

unutbu
unutbu

Reputation: 880937

With NumPy 1.7 or newer, use np.random.choice, with replace=False:

In [85]: X = np.array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

In [86]: np.random.choice(X, 3, replace=False)
Out[86]: array([7, 5, 9])

Upvotes: 8

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