The NumPy where function is like a vectorized switch that you can use to combine two arrays.
The np.all() function tests whether all elements in a NumPy array evaluate to true.
You can calculate the L1 and L2 norms of a vector or the Frobenius norm of a matrix in NumPy with np.linalg.norm(). This post explains the API and gives a few concrete usage examples.
Using and suppressing scientific notation in Python and NumPy.
The unofficial guide to np.tile() with examples.