Dijkstra Algorithm Help

[yoro]

On Mar 8, 6:49 pm, MRAB <pyt... at mrabarnett.plus.com> wrote:
> On 08/03/2011 18:12, yoro wrote:
>
>
>
> > Hello,
>
> > I am having a little trouble writing Dijkstra's Algorithm, at the
> > point where I have to calculate the distance of each node from the
> > source - here is my code so far:
>
> > infinity = 1000000
> > invalid_node = -1
> > startNode = 0
>
> > class Node:
> >       distFromSource = infinity
> >       previous = invalid_node
> >       visited = False
>
> > def populateNodeTable():
> >      nodeTable = []
> >      index =0
> >      f = open('route.txt', 'r')
> >      for line in f:
> >        node = map(int, line.split(','))
>
> "node" will be a list of ints, but you're not doing anything with them.
>
>
>
> >        nodeTable.append(Node())
> >        print nodeTable[index].previous
> >        print nodeTable[index].distFromSource
> >        index +=1
> >      nodeTable[startNode].distFromSource = 0
>
> >      return nodeTable
>
> > def tentativeDistance(currentNode, nodeTable):
> >      nearestNeighbour = []
> >      for currentNode in nodeTable:
> >           if Node[currentNode].distFromSource +
> > #   currentDistance = + nodeTable[currentNode]
> > #      currentDistance = currentNode.distFromSource +
> > nodeTable.currentNode
> >           currentNode.previous = currentNode
> >           currentNode.length = currentDistance
> >           currentNode.visited = True
> >           currentNode +=1
> >           nearestNeighbour.append(currentNode)
> >           print nearestNeighbour
>
> >      return nearestNeighbour
>
> > currentNode = startNode
>
> > if __name__ == "__main__":
> >      populateNodeTable()
>
> The only effect of "populateNodeTable" is to return a node table, which
> is then discarded.
>
> >      tentativeDistance(currentNode,populateNodeTable())
>
> > As can be seen from the lines commented out, I have tried a few ways
> > of getting the distance though none of them has worked; I am not sure
> > on how I can resolve this problem
>
>

Thanks for replying, maybe i'm misunderstanding your comment -
nodeTable is used to store the distances from source of each node
within a text file, the file having the format :

1,2,3,4,5,6,7,8,9
1,2,3,4,5,6,7,8,9

Each of these nodes will have the same settings as set out in Class
Node, i.e. all having no previous nodes. I am then trying to pass this
parameter to the next function so that the distance from the start
node can be calculated