Iterating over numpy array rows in python

Question

I am trying to iterate over the rows of two numpy arrays in python, using the following for loop:

for i, j in range(X.shape[0]), range(y.shape[0]):

But I am getting the following error:

ValueError: too many values to unpack (expected 2)

I thought that by creating lists with the number of rows in each array I could iterate over X using the value of i, and over y using the value of j.

Could somebody please explain why this is not working, and how I could make it work instead? Thanks!

Answer 1

This is not what you are looking to do.

To iterate over rows in X and rows in Y, you should use nested loops:

for i in range(X.shape[0]):
    for j in range(Y.shape[0]):
        func(i, j)

Having said this, I would strongly advise you use loops as a last resort. Try to vectorise functions where possible.

If you must loop, you may be able to improve performance by using numba.