binary tree issue: unorderable types: str() < int()

Question

I am trying to create a binary tree. I am testing what I have with the test code at the bottom but I receive the error message "elif var < here._variable: TypeError: unorderable types: str() < int()" any insight would be great

class vartree:

    class Node:

        __slots__= "_left", "_value", "_variable", "_right"
        def __init__ (self, l, var,val,r):
             self._left = l
             self._variable = var
             self._value = val
             self._right = r

    def __init__(self):
        self._root = None

    def _search (self, here, var):
        if  here is None:
            return self.Node(None, var, '0', None)

        elif var < here._variable:
            return self._search(here._left, var)

        elif var > here._variable:
            return self._search(here._right, var)

        else:
            return here._value

    def _insert(self, here, var, val):
        if here is None:
            return self.Node(None, val, var, None)

        elif var < here._variable:
            return self.Node(self._insert(here._left, var, val), here._value, here._variable, here._right)

        elif var > here._variable:
            return self.Node(here._left , here._value, here._variable, self._insert(here._right, var, val))

        else:
            return var

    def assign(self, var, val):
        self._root = self._insert(self._root, var, val)
        #self._insert(self._root, var, val)

    def lookup(self, var):
        return self._search(self._root, var)


if __name__ == "__main__":
    T = vartree()
    T.assign("x",9)
    T.lookup("x")

Answer 1

The problem is that one is an integer and the other a string at the line at which error occurs. After analyzing your code, i think i know why this is happening. Do this:

In your _insert() function, change this line:

  return self.Node(None, val, var, None)

to this:

return self.Node(None, var, val, None)

Hope this help :)