Binary Search Tree - storing reference to parent node

Question

I hope someone can help me, I'm not a programming professional, but am using Python to learn and experiment with binary trees.

Below is the code I have, and have attempted to try and store a reference to a node's parent in it's node, the storing of it's parent node, won't work for leaf nodes though. Is there a way of doing this during the process of building the tree?

I'd also like to know for a given node, whether is's a 'Left or 'Right' node. I thought seeing as the node is stored in an instance of TreeNode.left or TreeNode.right, I might be able to get a reference to this in Python, as in n._name_ or something like that. Could you tell me the correct way to find whether a node is left or right?

My ultimate goal will be to visualise my tree through a level order traversal.

class TreeNode:
 left, right, data = None, None, 0

def __init__(self,nodeData, left = None, right = None, parent = None):
 self.nodeData = nodeData
 self.left = left
 self.right = right
 self.parent = self

class Tree:
 def __init__(self):
  self.root = None

 def addNode(self, inputData):
  return TreeNode(inputData)

 def insertNode(self, parent, root, inputData):
  if root == None:
   return self.addNode(inputData)
  else:
   root.parent = parent
   if inputData <= root.nodeData:
    root.left = self.insertNode(root, root.left, inputData)
   else:
    root.right = self.insertNode(root, root.right, inputData)
   return root

Answer 1

There are many, many things wrong with this. Since it's homework, I'll supply one hint.

def __init__(self,nodeData, left = None, right = None, parent = None):
 self.nodeData = nodeData
 self.left = left
 self.right = right
 self.parent = self

Why isn't self.parent set to parent?