在二维数组中查找给定特定坐标的邻居

Question

I am trying to solve a problem using python and this is my first time to write python so I hope you could help me out. I have a 2D array its values is -1,0,1 what I want to do is take the co-ordinates of a specific element and get the co-ordinates of all the adjacent elements

Matrix = [[ 1,-1, 0],
          [ 1, 0, 0],
          [-1,-1, 1]]

for example if I have (0,0) so the function could return (0,1) , (1,0)

Answer 1

Since you want to work from the coordinates , a simple way I can think of is to define a grid graph using NetworkX and to look for the neighbours :

import networkx as nx
import numpy as np

a = np.array([[1,-1,0],
              [1,0,0],
              [-1,-1,1]])

G = nx.grid_2d_graph(*a.shape)
list(G.neighbors((0,0)))
# [(1, 0), (0, 1)]

Or for the "coordinates" of the middle value for instance:

list(G.neighbors((1,1)))
# [(0, 1), (2, 1), (1, 0), (1, 2)]

If you want to use them to index the array:

ix = list(G.neighbors((0,0)))
a[tuple(ix)]
# array([ 1, -1])

Answer 2

It's not the best solution but it can help if you don't want to import any lib:

def get_neighbors(matrix, x, y):
    positions = []
    positions.append(get_neighbor(matrix, x, y-1))
    positions.append(get_neighbor(matrix, x, y+1))
    positions.append(get_neighbor(matrix, x-1, y))
    positions.append(get_neighbor(matrix, x+1, y))

    return list(filter(None, positions))

def get_neighbor(matrix, x, y):
    if (x >= 0 and x < len(matrix[0])) and (y >= 0 and y < len(matrix[1])):
        return (x, y)

get_neighbors(your_matrix, x_position, y_position)