Passing Functions

[yoro]

Hi,

I am having an issue with passing values from one function to another
- I am trying to fill a list in one function using the values
contained in other functions as seen below:

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

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

So, I am trying to look at the values provided by the network
function, set all nodes to 'visited = false' in populateNodeTable
function and then determine the nodes' nearest neighbour by looking at
the values provided in the previous function, though I get this error
message:

if node != 0 and currentNode.visited == false:
AttributeError: 'int' object has no attribute 'visited'

I'm not sure what to try next

 

[alex23]

Hi,

I am having an issue with passing values from one function to another
- I am trying to fill a list in one function using the values
contained in other functions as seen below:

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

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

So, I am trying to look at the values provided by the network
function,  set all nodes to 'visited = false' in populateNodeTable
function and then determine the nodes' nearest neighbour by looking at
the values provided in the previous function, though I get this error
message:

if node != 0 and currentNode.visited == false:
AttributeError: 'int' object has no attribute 'visited'

I'm not sure what to try next

Well, for starters, you're not actually instantiating any Nodes:

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

You're returning a list of integers, none of which have the visited
attribute.

At the very least, you need a constructor on your Node class:

class Node:
def __init__(self, distFromSource=infinity, previous=invalid_node,
visited=False):
self.distFromSource = distFromSource
self.previous = previous
self.visited = False

Now, I'm _assuming_ your network.txt file consists of 3 number
separated by commas, so in network() it should probably be something
like:

def network():
with open('network.txt', 'r') as f:
network_data = ([int(node) for node in line.split(',')] for line
in f.readlines())
theNetwork = [Node(*data) for data in network_data]
return theNetwork

The with statement ensures the file is closed at the end of the block.
'network_data' is a generator that reads each line and splits it into
a list of ints: '[x, y, z]'
'Node(*data)' takes a list of ints and creates a node from those
values.

Since both populateNodeTable and nearestNeighbour relay on nodeTable,
you might be better off making a NodeTable class.

None of this is tested, sorry, but hopefully it'll set you in the
right direction.

 

[MRAB]

Hi,

I am having an issue with passing values from one function to another
- I am trying to fill a list in one function using the values
contained in other functions as seen below:

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

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

So, I am trying to look at the values provided by the network
function, set all nodes to 'visited = false' in populateNodeTable
function and then determine the nodes' nearest neighbour by looking at
the values provided in the previous function, though I get this error
message:

if node != 0 and currentNode.visited == false:
AttributeError: 'int' object has no attribute 'visited'

I'm not sure what to try next

In nearestNeighbour, 'currentNode' is an int because that's what you're
passing in ... except that you aren't.

You're passing in the value of the global 'currentNode', which doesn't
exist. Perhaps you meant 'startNode'?

When I run the above program I get:

Traceback (most recent call last):
File "C:\Documents and Settings\Administrator\Desktop\network.py",
line 49, in <module>
nearestNeighbour(currentNode, theNetwork, )
NameError: name 'currentNode' is not defined

 

[yoro]

Hi,

I am having an issue with passing values from one function to another
- I am trying to fill a list in one function using the values
contained in other functions as seen below:

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

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

So, I am trying to look at the values provided by the network
function,  set all nodes to 'visited = false' in populateNodeTable
function and then determine the nodes' nearest neighbour by looking at
the values provided in the previous function, though I get this error
message:

if node != 0 and currentNode.visited == false:
AttributeError: 'int' object has no attribute 'visited'

I'm not sure what to try next

In nearestNeighbour, 'currentNode' is an int because that's what you're
passing in ... except that you aren't.

You're passing in the value of the global 'currentNode', which doesn't
exist. Perhaps you meant 'startNode'?

When I run the above program I get:

Traceback (most recent call last):
   File "C:\Documents and Settings\Administrator\Desktop\network.py",
line 49, in <module>
     nearestNeighbour(currentNode, theNetwork, )
NameError: name 'currentNode' is not defined

I've found the error, I had to type in:

for node in nodeTable:
if node != 0 and Node.visited == False:

 

[John Nagle]

I've found the error, I had to type in:

for node in nodeTable:
if node != 0 and Node.visited == False:

That's just your first error.
(Also, you shouldn't have anything but Node items in
nodeTable, so you don't need the "node != 0".)

The biggest problem is at

#Values to assign to each node
Those are variables of the entire class. Every
instance of Node shares the same variables. You
need

class Node:
def __init__(self) :
self.distFromSource = infinity
self.previous = invalid_node
self.visited = False

John Nagle