Question

我正在努力研究如何从函数中传递参数，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，我试图在最近的邻居函数中填充最近的邻居列表，其中包含最接近其他节点的节点列表。现在，所有其他函数都正常工作，所有参数传递都应该正常运行。但是，my nearestNeighbour函数会抛出此错误消息：

如果节点！= 0和 theNetwork [currentNode] .visited == false：AttributeError：'list'对象没有'已访问'属性

（对于布局抱歉，还没有完全理解代码引用的使用）

Answer 1

那是因为theNetwork[currentNode]返回一个列表。换句话说：theNetwork是一个列表列表。

这是完成它的路线：

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

Answer 2

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 3

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

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

也许你想要的东西是：

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

Python - 传递函数参数

3 个答案: