Get mean of 2D slice of a 3D array in numpy

Question

I have a numpy array with a shape of:

(11L, 5L, 5L)

I want to calculate the mean over the 25 elements of each \'slice\' of the array [0, :,

Answer 1

Use a tuple for axis :

>>> a = np.arange(11*5*5).reshape(11,5,5)
>>> a.mean(axis=(1,2))
array([  12.,   37.,   62.,   87.,  112.,  137.,  162.,  187.,  212.,
        237.,  262.])

Edit: This works only with numpy version 1.7+.