add a traversal func

lambdaplus · lambdaplus · commit 4fc6b520eda0 · 2016-07-24T15:27:07.000+08:00
diff --git a/traversal.py b/traversal.py
@@ -0,0 +1,34 @@
+# -*- coding: utf-8 -*-
+'''
+from collections import Iterable
+def flat(items, L=None):
+	if L is None:
+		L = []
+	for item in items:
+		if isinstance(item, Iterable):
+			return flat(item, L)
+		else:
+			L.append(item)
+
+	return L
+			
+if __name__ == "__main__":
+	items = [1, 2, [3, 4, [5, 6, 7], 8, 9]]
+	new_items = flat(items)
+	print(new_items)
+'''
+from collections import Iterable
+def flat(items, ignore_types=(str, bytes)):
+	'''
+	http://python3-cookbook.readthedocs.io/zh_CN/latest/c04/p14_flattening_nested_sequence.html
+	'''
+	for item in items:
+		if isinstance(item, Iterable) and not isinstance(item, ignore_types):
+			yield from flat(item)
+		else:
+			yield item
+
+if __name__ == "__main__":
+	items = [1, 2, [3, 4, [5, 6, 7], 8], 9]
+	for i in flat(items):
+		print(i)
