numpy duplicate elements

Question

maybe this is a easy question, but is there a fast way to duplicate elements in a array? It should work like this way for 3D:

1 2 3
4 5 6
7 8 9

1 1 2 2 3 3
1 1 2 2 3 3
4 4 5 5 6 6
4 4 5 5 6 6
7 7 8 8 9 9
7 7 8 8 9 9

I tried it with 3 nested for-loops, but this was really slow.

eumiro · Accepted Answer · 2012-12-20 09:34:57Z

6

>>> a = np.array([[1, 2, 3],
                  [4, 5, 6],
                  [7, 8, 9]])
>>> np.repeat(np.repeat(a, 2, 0), 2, 1)

array([[1, 1, 2, 2, 3, 3],
       [1, 1, 2, 2, 3, 3],
       [4, 4, 5, 5, 6, 6],
       [4, 4, 5, 5, 6, 6],
       [7, 7, 8, 8, 9, 9],
       [7, 7, 8, 8, 9, 9]])

answered Dec 20, 2012 at 9:34

eumiro

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3 Comments

Christian Over a year ago

Great Solution! But I figured out that this function change the dtype from float64 to float32. Can I avoid this?

eumiro Over a year ago

@Christian - it doesn't change the dtype for me.

Christian Over a year ago

sorry, my fault - I used another function which destroyed the dtype. thanks! :)

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