connected_components_bfs.py

from collections import deque

field = [...]  # NxM matrix
not_visited = {(x, y) for x in range(N) for y in range(M)}


def test_acceptance(x, y):
    return field[x][y] == 1 and (x, y) in not_visited


def bfs(start_x, start_y):
    queue = deque()
    queue.append((start_x, start_y))

    connected_component = set()

    while queue:
        x, y = queue.popleft()
        
        if test_acceptance(x, y):
            connected_component.add((x, y))

            for i in (-1, 1):
                next_x, next_y = x + i, y + i
                
                if 0 <= next_x < N:
                    queue.append((next_x, y))
                    
                if 0 <= next_y < M:
                    queue.append((x, next_y))

        not_visited.discard((x, y))

    return connected_component


all_components = []

while not_visited:
    x, y = not_visited.pop()
    all_components.append(bfs(x, y))