import numpy as np

readings = np.arange(1, 21).reshape(4, 5)

single = readings[2, 3]
row = readings[2, :]
column = readings[:, 3]
window = readings[1:3, 2:5]
stepped = readings[::2, ::-1]

print("readings:")
print(readings)
print("single readings[2, 3]:", single)
print("row readings[2, :]:", row)
print("column readings[:, 3]:", column)
print("window readings[1:3, 2:5]:")
print(window)
print("stepped readings[::2, ::-1]:")
print(stepped)
print("window shares memory:", np.shares_memory(readings, window))

assert single == 14
assert row.tolist() == [11, 12, 13, 14, 15]
assert column.tolist() == [4, 9, 14, 19]
assert window.tolist() == [[8, 9, 10], [13, 14, 15]]
assert stepped.tolist() == [[5, 4, 3, 2, 1], [15, 14, 13, 12, 11]]
assert np.shares_memory(readings, window)

print("indexing checks passed")