Modify a binary tree in python

Question

I have a binary tree with 7 elements which currently looks like this:

 1
 5 2
7 6 4 3

I am trying to traverse it in postorder and relable the elements as I go, so that it looks like this:

 7
 3 6
1 2 4 5

using the following function, which is part of my Tree class:

def relable(self, h):
 if self.root is not None:
 self._relable(self.root, h)
def _relable(self, node, h):
 if node is not None:
 self._relable(node.l, h-2)
 self._relable(node.r, h-1)
 node = Node(h)

The rest of my Tree class is more or less the same as the one here. I populated the tree by adding the numbers 1-7 in a loop.

However, when I call tree.relable(7), and then print the tree, the tree is the same. I'm guessing this has something to do with how Python passes arguments (I'm a C++ programmer) but I don't know how to fix this. The entirety of my code can be fount here.

Answer 1

node = Node(h) is just assigning a local variable, it doesn't have any effect on the node parameter that was passed to the function. You need to actually modify the node, i.e. node.v = h.