cleaning up and organizing old problems (builtin)

src/USEFUL/basic_examples/example_OrderedDict.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python
+
+__author__ = "bt3"
+
+from collections import OrderedDict
+
+def  OrderedDict_example():
+    ''' show some examples for OrderedDict '''
+    ''' keep the order of insertion.
+        maintains a doubly linked list, so size is more than twice than normal dict'''
+
+
+    pairs = [('a', 1), ('b',2), ('c',3)]
+
+    d1 = {}
+    for key, value in pairs:
+        if key not in d1:
+            d1[key] = []
+        d1[key].append(value)
+    for key in d1:
+        print(key, d1[key])
+
+    d2 = OrderedDict(pairs)
+    for key in d2:
+        print(key, d2[key])
+
+
+if __name__ == '__main__':
+    OrderedDict_example()
+
+