How to switch axes (dimensions) in Julia for n-dimensional array

Question

I have an array that I would like to switch the axes order of. It is similar to a transpose except I would like to perform it on arrays with dimensions greater than 2. In Python I would use np.transpose and in Matlab, permute, but I can't seem to find this in Julia. For instance,

a = ones(2, 3, 4)
size(a)
(2,3,4)

From this I would like to get an array of shape (3, 4, 2) by rearranging the axes (dimensions) to (2, 3, 1). I am looking for a function called new_func.

b = new_func(a, (2, 3, 1))
size(b)
(3,4,2)

Is http://docs.julialang.org/en/latest/stdlib/base/#Base.permutedims what you're looking for? — StefanKarpinski, Jul 20 '14 at 02:12
No worries. I guess I should post an answer, but s.o. generally doesn't like single-link answers. — StefanKarpinski, Jul 20 '14 at 19:35

score 10 · Answer 1 · answered Jan 15 '15 at 04:50

10

According to Stefan Karpinski, the answer is Base.permutedims (docs).

Example:

a = ones(2, 3, 4)
size(a) # => (2,3,4)

b = permutedims(a, [2, 3, 1])
size(b) # => (3,4,2)

answered Jan 15 '15 at 04:50

Kipton Barros

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How to switch axes (dimensions) in Julia for n-dimensional array

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