Python - 传递函数参数

Question

我正在努力弄清楚如何从函数传递参数，以便我可以在另一个函数中填充列表 - 我的代码是：

 infinity = 1000000 
 invalid_node = -1 
 startNode = 0

#Values to assign to each node 
class Node:
     distFromSource = infinity
     previous = invalid_node
     visited = False

#read in all network nodes 
def network():
    f = open ('network.txt', 'r')
    theNetwork = [[int(node) for node in line.split(',')] for line in f.readlines()]
    print theNetwork

    return theNetwork

#for each node assign default values 
def populateNodeTable(): 
    nodeTable = []
    index = 0
    f = open('network.txt', 'r')
    for line in f: 
      node = map(int, line.split(',')) 
      nodeTable.append(Node())

      print "The previous node is " ,nodeTable[index].previous 
      print "The distance from source is " ,nodeTable[index].distFromSource 
      index +=1
    nodeTable[startNode].distFromSource = 0 

    return nodeTable

#find the nearest neighbour to a particular node 
def nearestNeighbour(currentNode, theNetwork):
     nearestNeighbour = []
     nodeIndex = 0
     for node in nodeTable:
          if node != 0 and currentNode.visited == false:
             nearestNeighbour.append(nodeIndex)
             nodeIndex +=1

     return nearestNeighbour

  currentNode = startNode

if __name__ == "__main__":
    nodeTable = populateNodeTable()
    theNetwork = network()
    nearestNeighbour(currentNode, theNetwork)

所以，我试图用最近的节点列表填充我的nearestNeighbour函数中的nearestNeighbour列表到其他节点。现在，所有其他函数都可以正常工作，所有参数传递都可以正常运行。 但是，我的nearestNeighbour函数会抛出此错误消息：

如果节点！= 0 并且 theNetwork[当前节点].visited == false：属性错误：“列表”对象 没有属性“访问过”

（对布局表示歉意，还没有完全理解代码引号的使用）

Answer 1

class Node(object):
    def __init__(self, me, dists):
        super(Node,self).__init__()
        self.me = me
        self.dists = dists
        _inf = Network.INF
        self.neighbors = sorted((i for i,dist in enumerate(self.dists) if i!=me and dist!=_inf), key=dists.__getitem__)
        self.clear()

    def clear(self):
        self.dist = None
        self.prev = None

    def nearestNeighbor(self):
        try:
            return self.neighbors[0]
        except IndexError:
            return None

    def __str__(self):
        return "{0}: {1}".format(self.me, self.dists)

class Network(object):
    INF     = 10**6

    @classmethod
    def fromFile(cls, fname, delim=None):
        with open(fname) as inf:
            return cls([[int(dist) for dist in line.split(delim)] for line in inf])

    def __init__(self, distArray):
        super(Network,self).__init__()
        self.nodes = [Node(me,dists) for me,dists in enumerate(distArray)]

    def __str__(self):
        return '\n'.join(self.nodes)

    def floodFill(self, fromNode):
        _nodes = self.nodes
        for n in _nodes:
            n.clear()
        _nodes[fromNode].dist = 0
        # left as an exercise ;-)

    def distances(self):
        return [n.dist for n in self.nodes]

def main():
    nw = Network.fromFile('network.txt', delim=',')
    print(nw)

    nw.floodFill(fromNode=0)
    print(nw.distances())

if __name__=="__main__":
    main()

Answer 2

这是因为 theNetwork[currentNode] 返回一个列表。换句话说：theNetwork 是一个列表的列表。

这是完成的行：

theNetwork = [[int(node) for node in line.split(',')] for line in f.readlines()]

Answer 3

 theNetwork = [[int(node) for node in line.split(',')] for line in f.readlines()]

theNetwork 是一个列表列表。列表 (theNetwork[currentNode]) 没有 visited 属性。

也许你的意图是这样的：

for line in f.readlines():
     theNetwork.extend((int(node) for node in line.split(',')))