Question

I’m running into trouble with some Python stuff. I have a list that has seven copies of a class and I am intending to change just the values of one of them but whenever I do it changes the value for all.

Here is the class:

class Node:
  previous = -1
  distFromSrc = 1000000
  visited = False

And here is how I create the list:

def createNodeTable(network):
  nodeTable = []
  for line in network:
    nodeTable.append(Node)
  return nodeTable

‘network’ is a list of length 7 so when I print the ‘nodeTable[x].visited’ before I attempt to make any changes to the values I get ‘False’ for every one.

If I call the following function however all of the ‘.visited’ values change to false not just the one I am intending to change.

Whatever ‘currentNode’ is changed to I get the same issue:

def setVisited(currentNode, nodeTable):
  nodeTable[currentNode].visited = True
  return nodeTable

Is there an issue with the setVisited function or is it to with the nodeTable? I don’t even know where to start to try to fix this.

Answer 1

nodeTable.append(Node)

The problem lies in that line. What you are doing there is that you append the type (or class) to the list. So you end up with a list of seven times the exact same type reference.

What you should do instead is creating instances of said type. You can do that by calling it.

nodeTable.append(Node())