calculating depth of a binary tree in Python

Question

I am new to programming and am trying to calculate the depth of a binary tree in Python . I believe that my error is because depth is a method of the Node class and not a regula

Answer 1

def depth(self):
    if self.left == None and self.right == None:
        return 1

    return max(depth(self.left), depth(self.right)) + 1

should be

def depth(self):
    return max(self.left.depth() if self.left else 0, self.right.depth() if self.right else 0) + 1

A more readable version:

def depth(self):
    left_depth = self.left.depth() if self.left else 0
    right_depth = self.right.depth() if self.right else 0
    return max(left_depth, right_depth) + 1

The issue is that there is no function depth. It's a method of the Node object, so you would need to call it from the object itself (left and right). I shortened the code to self.left.depth() if self.left else 0 and self.right.depth() if self.right else 0 in order to remove the checks you previously have (they're implicit now) since I believe it is entirely possible that the left is None while the right is a Node or vice versa, which would cause the original code to throw an AttributeError since None does not have a method depth.

Edit

In response to the question about the if else block:

The line gives if is true-y (treated as true), and if is false-y (treated as false)