Delete columns from numpy array depending on a condition on a single cell

Question

Above all, sorry for my bad English.

I have this array t:

array([[ 0,  1,  2,  0,  4,  5,  6,  7,  8,  9],
       [ 0, 11,  0, 13,  0, 15,  0, 17, 18,  0]])

I would like to delete the columns where the value of second line is null. Here, I would like to delete the columns 0, 2, 4, 6 and 9, to obtain this array:

array([[  1,   0,   5,   7,  8 ],
       [ 11,  13,  15,  17, 18 ]])

I tried with np.sum() but didn't succeed.

Answer 1

Similar to Juh_, but more expressive, and avoiding some minor unnecessary performance overhead. A grand total of 12 highly pythonic, explicit and unambigious characters. This is really numpy 101; if you are still trying to wrap your head around this, you would do yourself a favor by reading a numpy primer.

import numpy as np
a = np.array([[ 0,  1,  2,  0,  4,  5,  6,  7,  8,  9],
              [ 0, 11,  0, 13,  0, 15,  0, 17, 18,  0]])
print a[:,a[1]!=0]

Answer 2

With numpy.delete:

a = np.array([[0, 1, 2, 0, 4, 5, 6, 7, 8, 9], [0, 11, 0, 13, 0, 15, 0, 17, 18, 0]])

indices = [i for (i,v) in enumerate(a[1]) if v==0]
# [0, 2, 4, 6, 9]

a = np.delete(a, indices, 1)
# array([[ 1,  0,  5,  7,  8], [11, 13, 15, 17, 18]])