title: Combining NumPy arrays
body: <p>I have two 20x100x3 <a href="http://en.wikipedia.org/wiki/NumPy" rel="noreferrer">NumPy</a> arrays which I want to combine into a 40 x 100 x 3 array, that is, just add more lines to the array. I am confused by which function I want: is it vstack, hstack, column_stack or maybe something else?</p>