Initial data commit

Task/Visualize-a-tree/Python/visualize-a-tree-6.py

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+'''Visualize a tree'''
+
+from itertools import (chain, repeat, starmap)
+from operator import (add)
+
+
+# drawTree :: Tree a -> String
+def drawTree(tree):
+    '''ASCII diagram of a tree.'''
+    return '\n'.join(draw(tree))
+
+
+# draw :: Tree a -> [String]
+def draw(node):
+    '''List of the lines of an ASCII
+       diagram of a tree.'''
+    def shift(first, other, xs):
+        return list(starmap(
+            add,
+            zip(
+                chain([first], repeat(other, len(xs) - 1)),
+                xs
+            )
+        ))
+
+    def drawSubTrees(xs):
+        return (
+            (
+                ['│'] + shift(
+                    '├─ ', '│  ', draw(xs[0])
+                ) + drawSubTrees(xs[1:])
+            ) if 1 < len(xs) else ['│'] + shift(
+                '└─ ', '   ', draw(xs[0])
+            )
+        ) if xs else []
+
+    return (str(root(node))).splitlines() + (
+        drawSubTrees(nest(node))
+    )
+
+
+# TEST ----------------------------------------------------
+# main :: IO ()
+def main():
+    '''Test'''
+
+    # tree :: Tree Int
+    tree = Node(1)([
+        Node(2)([
+            Node(4)([
+                Node(7)([])
+            ]),
+            Node(5)([])
+        ]),
+        Node(3)([
+            Node(6)([
+                Node(8)([]),
+                Node(9)([])
+            ])
+        ])
+    ])
+
+    print(drawTree(tree))
+
+
+# GENERIC -------------------------------------------------
+
+
+# Node :: a -> [Tree a] -> Tree a
+def Node(v):
+    '''Contructor for a Tree node which connects a
+       value of some kind to a list of zero or
+       more child trees.'''
+    return lambda xs: {'root': v, 'nest': xs}
+
+
+# nest :: Tree a -> [Tree a]
+def nest(tree):
+    '''Accessor function for children of tree node.'''
+    return tree['nest'] if 'nest' in tree else None
+
+
+# root :: Dict -> a
+def root(dct):
+    '''Accessor function for data of tree node.'''
+    return dct['root'] if 'root' in dct else None
+
+
+# MAIN ---
+if __name__ == '__main__':
+    main()