when should i use hstack/vstack vs append vs concatenate vs column_stack

Question

Simple question: what is the advantage of each of these methods. It seems that given the right parameters (and ndarray shapes) they all work seemingly equivalently. Do some

Answer 1

In IPython you can look at the source code of a function by typing its name followed by ??. Taking a look at hstack we can see that it's actually just a wrapper around concatenate (similarly with vstack and column_stack):

np.hstack??
def hstack(tup):
...
    arrs = [atleast_1d(_m) for _m in tup]
    # As a special case, dimension 0 of 1-dimensional arrays is "horizontal"
    if arrs[0].ndim == 1:
        return _nx.concatenate(arrs, 0)
    else:
        return _nx.concatenate(arrs, 1)

So I guess just use whichever one has the most logical sounding name to you.