Introduction

In computer science, a tree is a data structure that is modeled after nature.  Unlike trees in nature, the tree data structure is upside down: the root of the tree is on top. A tree consists of nodes and its connections are called edges. The bottom nodes are also named leaf nodes. A tree may not have a cycle.

 

A tree with eight nodes. The root of the tree (5) is on top.

Python does not have built-in support for trees.

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• Practice Python with interactive exercises
• Practice Python with interactive exercises

Binary tree

A binary tree is a data structure where every node has at most two children (left and right child).   The root of a tree is on top. Every node below has a node above known as the parent node.We define a class thee which has a left and right attribute. From this binary tree we define the root (top of the three) and a left and right node.

#!/usr/bin/env python
class Tree(object):
    def __init__(self):
        self.left = None
        self.right = None
        self.data = None
root = Tree()
root.data = "root"
root.left = Tree()
root.left.data = "left"
root.right = Tree()
root.right.data = "right"
print(root.left.data)

You could then further create the tree like this:

#!/usr/bin/env python
class Tree(object):
    def __init__(self):
        self.left = None
        self.right = None
        self.data = None
root = Tree()
root.data = "root"
root.left = Tree()
root.left.data = "left"
root.right = Tree()
root.right.data = "right"
root.left.left = Tree()
root.left.left.data = "left 2"
root.left.right = Tree()
root.left.right.data = "left-right"