On Mar 8, 6:49 pm, MRAB <pyt...@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
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