CODEWITHSUNDEEP
pythonjsongraph
Kamal
Kamal

Reputation: 630

Getting a has no attribute error in python, not sure why because the attributes are clearly defined

So I'm working on a program which involves representing airline flights as a graph. I have a GraphImplementation.py file here, which implements the graph:

class Node:
    def __init__(self, city, code, country, continent, tZone, lat, long, pop, region):
    self.city = city
    self.code = code
    self.country = country
    self.continent = continent
    self.tZone = tZone
    self.lat = lat
    self.long = long
    self.pop = pop
    self.region = region
    self.connections = {}

def addNeighbor(self, neighborNode, length=0):
    self.connections[neighborNode] = length

def __str__(self):
    return str(self.city) + ' connections: ' + str([x.city for x in self.connections])

def getConnections(self):
    return self.connections.keys()

def getCity(self):
    return self.city

def getWeight(self,node):
    return self.connections[node]

class Graph:
def __init__(self):
    self.nodeList = {}
    self.nodeCnt = 0

def addNode(self, newNode):
    self.nodeCnt = self.nodeCnt + 1
    self.nodeList[newNode.city] = newNode
    return newNode

def getNode(self,city):
    if city in self.nodeList:
        return self.nodeList[city]
    else:
        return None

def __contains__(self,n):
    return n in self.nodeList

def addEdge(self,f, fNode, t, tNode, cost=0):
    if f not in self.nodeList:
        nv = self.addNode(fNode)
    if t not in self.nodeList:
        nv = self.addNode(tNode)
    self.nodeList[f].addNeighbor(self.nodeList[t], cost)

def getNodes(self):
    return self.nodeList.keys()

def longestFlight(self):
    print "enter"
    longestFlight = None
    maxCost = None
    for nodeCity, node in nodeList.iteritems():
        for connection, cost in node.connections.iteritems():
            print cost
            if cost > maxCost:
                maxCost = cost
                longestFlight = node.city + " to " + connection.city

    return longestFlight    

def __iter__(self):
    return iter(self.nodeList.values())

As you can see, the method "longestFlight()", which returns a string containing the longest flight, is clearly defined.

Below is the main program where I try to invoke the longestFlight() method (prior to this i load the graph data from a json file).

import json
import GraphImplementation as G
from ParseJson import parseJSONToGraph

def main():
jsonFile = open("map_data.json")
jsonData = json.load(jsonFile)
graph = G.Graph()
graph = parseJSONToGraph(graph, jsonData)

cont = 'y'
#Enter main loop
while cont == 'y':
    print " Menu options:"
    print " 1: get longest flight "
    menuChoice = raw_input("Enter menu choice: ")
    print menuChoice
    if int(menuChoice) == 1:
        print graph.longestFlight() + "\n"

    cont = raw_input("Do you want to continue? (y/n)")




if __name__ == "__main__":
    main()

When I run my main program and I try to invoke the longestFlight() method on my graph however (on line 24), I get the following error from python: Traceback (most recent call last):

  File "main.py", line 32, in <module>
    main()
  File "main.py", line 24, in main
    print graph.longestFlight() + "\n"
AttributeError: Graph instance has no attribute 'longestFlight'

Upvotes: 0

Views: 328

Answers (1)

JGerulskis
JGerulskis

Reputation: 808

Your indentation is not correct on your classes. When compiled the compiler doesnt think the longestFlight() function belongs to graph therefor giving you AttributeError: Graph instance has no attribute 'longestFlight'. Tab in your methods below your class headings like this:

class Graph:
    # other functions indented like this also
    def longestFlight():
        # do whatever

Upvotes: 1

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