Iterate over 2d array in an expanding circular spiral

Question

Given an n by n matrix M, at row i and column j, I\'d like to iterate over all the neighboring values in a c

Answer 1

Although I'm not entirely sure what you are trying to do, I'd start like this:

def xxx():
    for row in M[i-R:i+R+1]:
        for val in row[j-R:j+r+1]:
            yield val

I'm not sure how much order you want for your spiral, is it important at all? does it have to be in increasing R order? or perhaps clockwise starting at particular azimuth?

What is the distance measure for R, manhattan? euclidean? something else?