python 函式對映 Python對映函式

我需要一些關於python的map函式的幫助。我正在嘗試執行此**，但出現錯誤：

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這是我的確切**，以及每個函式的輸出：infinity = 1000000

invalid_node = -1

startnode = 0

#values to assign to each node

class node:

def __init__(self):

self.distfromsource = infinity

self.previous = invalid_node

self.visited = false

#read in all network nodes

#node = the distance values between nodes

def network():

f = open ('network.txt', 'r')

thenetwork = [[int(networknode) for networknode in line.split(',')] for line in f.readlines()]

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

print thenetwork

return thenetwork

#for each node assign default values

#populate table with default values

def populatenodetable():

nodetable =

index = 0

f = open('network.txt', 'r')

for line in f:

networknode = map(int, line.split(','))

print "the previous node is " ,nodetable[index].previous

print "the distance from source is " ,nodetable[index].distfromsource

#print networknode

index +=1

nodetable[startnode].distfromsource = 0

return nodetable

currentnode = startnode

#find the nearest neighbour to a particular node

def nearestneighbour(currentnode, thenetwork):

listofneighbours =

nodeindex = 0

for networknode in thenetwork[currentnode]:

if networknode != 0 and nodetable[nodeindex].visited == false:

nodeindex +=1

print "the nearest neighbours are", listofneighbours

## #print node.distfromsource, node.previous, node.visited

return listofneighbours

def tentativedistance (thenetwork, listofneighbours):

shortestpath =

for nodeindex in thenetwork:

currentdistance = listofneighbours[nodeindex] + startnode

print currentdistance

if currentdistance[thenetwork][nodeindex] < node.distfromsource:

thenetwork[node].previous = nodeindex

thenetwork[node].distfromsource = nodeindex

thenetwork[node].visited = true;

nodeindex +=1

print shortestpath

if __name__ == "__main__":

nodetable = populatenodetable()

#nodetable = populatenodetable(self)

thenetwork = network()

#listofneighbours = nearestneighbour(currentnode, thenetwork)

#tentativedistance(thenetwork, listofneighbours)

我的網路功能的輸出是乙個二維列表：

^$我的populatenodetable函式的輸出是：the previous node is -1