focal_ops_py
performing focal operation on 2-d arrays in python
the goal is to make the operating function and window size customizable and maybe add some other features
the code for window selection in the focal_ops function is from https://www.moonbooks.org/Articles/How-to-extract-a-small-matrix-by-selecting-neighbors-for-a-given-index-using-numpy-in-python-/Edit/