Combining NumPy arrays
One of the best ways of learning is experimenting, but I would say you want np.vstack although there are other ways of doing the same thing:
a = np.ones((20,100,3))b = np.vstack((a,a)) print b.shape # (40,100,3)or
b = np.concatenate((a,a),axis=0)EDIT
Just as a note, on my machine for the sized arrays in the OP's question, I find that np.concatenate is about 2x faster than np.vstack
In [172]: a = np.random.normal(size=(20,100,3))In [173]: c = np.random.normal(size=(20,100,3))In [174]: %timeit b = np.concatenate((a,c),axis=0)100000 loops, best of 3: 13.3 us per loopIn [175]: %timeit b = np.vstack((a,c))10000 loops, best of 3: 26.1 us per loop