Added added generic tree in python, issue no. BaReinhard#347

data_structures/generic_tree/python/gt.py

@@ -0,0 +1,238 @@
+# Trees:
+#   http://en.wikipedia.org/wiki/Tree_(data_structure)
+#   http://en.wikipedia.org/wiki/Tree_traversal
+#   http://en.wikipedia.org/wiki/Binary_tree
+
+class BinaryTree(object):
+    """Binary tree."""
+    def __init__(self, name='', left=None, right=None):
+        self.name = name
+        self.left = left
+        self.right = right
+    def __str__(self):
+        return str(self.name)
+
+def walk_btree_df_preorder(node, visit):
+    """Depth-first pre-order."""
+    if node is None:
+        return
+    visit(node)
+    walk_btree_df_preorder(node.left, visit)
+    walk_btree_df_preorder(node.right, visit)
+
+def walk_btree_df_inorder(node, visit):
+    """Depth-first in-order."""
+    if node is None:
+        return
+    walk_btree_df_inorder(node.left, visit)
+    visit(node)
+    walk_btree_df_inorder(node.right, visit)
+
+def walk_btree_df_postorder(node, visit):
+    """Depth-first post-order."""
+    if node is None:
+        return
+    walk_btree_df_postorder(node.left, visit)
+    walk_btree_df_postorder(node.right, visit)
+    visit(node)
+
+def walk_btree_df_preorder_iter(node, visit):
+    parent = []
+    while parent or node:
+        if node:
+            visit(node)
+            if node.right:
+                parent.append(node.right)
+            node = node.left
+        else:
+            node = parent.pop()
+
+def walk_btree_df_inorder_iter(node, visit):
+    parent = []
+    while parent or node:
+        if node:
+            parent.append(node)
+            node = node.left
+        else:
+            node = parent.pop()
+            visit(node)
+            node = node.right
+
+def walk_btree_df_postorder_iter(node, visit):
+    parent = []
+    last_visited = None
+    while parent or node:
+        if node:
+            parent.append(node)
+            node = node.left
+        else:
+            peeknode = parent[-1]
+            if peeknode.right and last_visited != peeknode.right:
+                node = peeknode.right
+            else:
+                visit(peeknode)
+                last_visited = parent.pop()
+
+def walk_btree_bf_iter(node, visit):
+    to_visit = [node]
+    while to_visit:
+        new_to_visit = []
+        for node in to_visit:
+            if node:
+                visit(node)
+                new_to_visit.append(node.left)
+                new_to_visit.append(node.right)
+        to_visit = new_to_visit
+
+def walk_btree_df_preorder_gen(node):
+    parent = []
+    while parent or node:
+        if node:
+            yield node
+            if node.right:
+                parent.append(node.right)
+            node = node.left
+        else:
+            node = parent.pop()
+
+def walk_btree_df_inorder_gen(node):
+    parent = []
+    while parent or node:
+        if node:
+            parent.append(node)
+            node = node.left
+        else:
+            node = parent.pop()
+            yield node
+            node = node.right
+
+def walk_btree_df_postorder_gen(node):
+    parent = []
+    last_visited = None
+    while parent or node:
+        if node:
+            parent.append(node)
+            node = node.left
+        else:
+            peeknode = parent[-1]
+            if peeknode.right and last_visited != peeknode.right:
+                node = peeknode.right
+            else:
+                yield peeknode
+                last_visited = parent.pop()
+
+def walk_btree_bf_gen(node):
+    to_visit = [node]
+    while to_visit:
+        new_to_visit = []
+        for node in to_visit:
+            if node:
+                yield node
+                new_to_visit.append(node.left)
+                new_to_visit.append(node.right)
+        to_visit = new_to_visit
+
+
+class Tree(object):
+    """Generic tree."""
+    def __init__(self, name='', children=None):
+        self.name = name
+        if children is None:
+            children = []
+        self.children = children
+    def __str__(self):
+        return str(self.name)
+
+def walk_tree_df_preorder(node, visit):
+    """Depth-first pre-order."""
+    visit(node)
+    for child in node.children:
+        walk_tree_df_preorder(child, visit)
+
+def walk_tree_df_postorder(node, visit):
+    """Depth-first post-order."""
+    for child in node.children:
+        walk_tree_df_preorder(child, visit)
+    visit(node)
+
+def walk_tree_bf(node, visit):
+    """Breadth-first (level order)."""
+    to_visit = [node]
+    while to_visit:
+        new_to_visit = []
+        for node in to_visit:
+            visit(node)
+            new_to_visit.extend(node.children)
+        to_visit = new_to_visit
+
+def walk_tree_bf_gen(node):
+    """Breadth-first (generator)."""
+    to_visit = [node]
+    while to_visit:
+        new_to_visit = []
+        for node in to_visit:
+            yield node
+            new_to_visit.extend(node.children)
+        to_visit = new_to_visit
+
+
+if __name__ == '__main__':
+    T = Tree
+    BT = BinaryTree
+    def visit(n):
+        print n
+    #    *
+    #   / \
+    #  1   +
+    #     / \
+    #    2   -
+    #       / \
+    #      3   4
+    bt = BT('*', BT(1), BT('+', BT(2), BT('-', BT(3), BT(4))))
+    print '->Binary Tree, Depth-First, Pre-Order'
+    walk_btree_df_preorder(bt, visit)
+    print '->Binary Tree, Depth-First, In-Order'
+    walk_btree_df_inorder(bt, visit)
+    print '->Binary Tree, Depth-First, Post-Order'
+    walk_btree_df_postorder(bt, visit)
+
+    print '->Binary Tree, Depth-First, Pre-Order (iteractive)'
+    walk_btree_df_preorder_iter(bt, visit)
+    print '->Binary Tree, Depth-First, In-Order (iteractive)'
+    walk_btree_df_inorder_iter(bt, visit)
+    print '->Binary Tree, Depth-First, Post-Order (iteractive)'
+    walk_btree_df_postorder_iter(bt, visit)
+
+    print '->Binary Tree, Depth-First, Pre-Order (generator)'
+    for n in walk_btree_df_preorder_gen(bt):
+        print n
+    print '->Binary Tree, Depth-First, In-Order (generator)'
+    for n in walk_btree_df_inorder_gen(bt):
+        print n
+    print '->Binary Tree, Depth-First, Post-Order (generator)'
+    for n in walk_btree_df_postorder_gen(bt):
+        print n
+    print '->Binary Tree, Breadth-First (generator)'
+    for n in walk_btree_bf_gen(bt):
+        print n
+
+    #           if
+    #         /  | \
+    #       /    |   \
+    #     cond  true false
+    #      |     |     |
+    #    equal  print end
+    #     /\     |
+    #    x  y   OK
+    t = T('if', [T('cond', [T('equal', [T('x'), T('y')])]),
+                 T('true', [T('print', [T('OK')])]),
+                 T('false', [T('end')])])
+    print '=>Tree, Depth-Frist, Pre-Order'
+    walk_tree_df_preorder(t, visit)
+    print '=>Tree, Depth-Frist, Post-Order'
+    walk_tree_df_postorder(t, visit)
+    print '=>Tree, Breadth-Frist'
+    walk_tree_bf(t, visit)
+    print '=>Tree, Breadth-Frist (generator)'
+    for n in walk_tree_bf_gen(t):
+        print n