图节点中的BFS

Question

Graph

I am trying to perform BFS on this graph starting from node 16. But my code is giving erroneous output. Can you please help me out. Thanks.

visited_nodes = set()
queue = [16]
pardaught = dict()
exclu = list()
path = set()
for node in queue:
    path.add(node)
    neighbors = G.neighbors(node)
    visited_nodes.add(node)
    queue.remove(node)
    queue.extend([n for n in neighbors if n not in visited_nodes])

newG = G.subgraph(path)
nx.draw(newG, with_labels=True)

My output is: Output

Answer 1

path should be a list , not set since set has no order. That should work:

visited_nodes = set()
path = []
queue = [16]

while queue:
    node = queue.pop(0)
    visited_nodes.add(node)
    path.append(node)

    for neighbor in G.neighbors(node):
        if neighbor in visited_nodes:
            continue
        queue.append(neighbor)

Answer 2

The cause of your problem is that you are removing things from (the start of) queue while looping through it. As it loops it steps ahead, but because the element is removed from the start, the list "steps" one in the opposite direction. The net result is that it appears to jump 2 at a time. Here's an example:

integer_list = [1,2,3]
next_int = 4
for integer in integer_list:
   print integer
   integer_list.remove(integer)
   integer_list.append(next_int)
   next_int += 1

Produces output

1

3

5