Finding neighbours in a two-dimensional array

Question

Is there an easy way of finding the neighbours (that is, the eight elements around an element) of an element in a two-dimensional array? Short of just subtracting and adding

Answer 1

This is an implementation of @Seb's answer in python3+ that is concise and uses generators for max performance:

def neighbours(pos, matrix):
    rows = len(matrix)
    cols = len(matrix[0]) if rows else 0
    for i in range(max(0, pos[0] - 1), min(rows, pos[0] + 2)):
        for j in range(max(0, pos[1] - 1), min(cols, pos[1] + 2)):
            if (i, j) != pos:
                yield matrix[i][j]