Query the faces of a cubical image in numpy

faces_of_array.py

import numpy as np

# Numpy array is xyz
img = np.zeros((10,20,30))

a = slice(None)  # all items, same as ':'

faces = {
  'top': (-1, a, a),
  'bottom': (0, a, a),
  'north': (a, -1, a),
  'south': (a, 0, a),
  'east': (a, a, -1),
  'west': (a, a, 0),
}

for face, slic in faces.items():
  print(face, img[slic].shape)