numpy array: IndexError: too many indices for array

Question

This works:

>>> a = np.array([[1,2,3,4], [5,6,7,8], [9,10,11,12]])
>>> a[: , 2]
array([ 3,  7, 11])

This doesn\'t

Answer 1

It's simple to see what the problem is. Try,

>>> a = np.array([[1,2,3,4], [5,6,7,8], [9,10,11,12]])
>>> a.shape

and then

>>>a = np.array([[1,2,3,4], [5,6,7,8], [9,10,11]])
>>> a.shape

and you will see the problem yourself, that in case two, shape is (3,).Hence the too many indices.