Trim / strip zeros of a numpy array

Use numpy.trim_zeros:

>>> import numpy as np
>>> a = np.array([0,0,0,3,2,-1,0,0,7,9,13,0,0,0,0,0,0,0])
>>> np.trim_zeros(a)
array([ 3,  2, -1,  0,  0,  7,  9, 13])

To trim 2d arrays:

def trim_zeros_2D(array, axis=1):
    mask = ~(array==0).all(axis=axis)
    inv_mask = mask[::-1]
    start_idx = np.argmax(mask == True)
    end_idx = len(inv_mask) - np.argmax(inv_mask == True)
    if axis:
        return array[start_idx:end_idx,:]
    else:
        return array[:, start_idx:end_idx]