reorganize dir

Signed-off-by: Mia Steinkirch <mia.steinkirch@gmail.com>

ebook_src/USEFUL/basic_examples/example_counter.py

@@ -0,0 +1,32 @@
+#!/usr/bin/env python
+
+__author__ = "bt3"
+
+from collections import Counter
+
+def  Counter_example():
+    ''' it is a dictionary that maps the items to the number of occurrences '''
+    seq1 = [1, 2, 3, 5, 1, 2, 5, 5, 2, 5, 1, 4]
+    seq_counts = Counter(seq1)
+    print(seq_counts)
+
+    ''' we can increment manually or use the update() method '''
+    seq2 = [1, 2, 3]
+    seq_counts.update(seq2)
+    print(seq_counts)
+
+    seq3 = [1, 4, 3]
+    for key in seq3:
+        seq_counts[key] += 1
+    print(seq_counts)
+
+    ''' also, we can use set operations such as a-b or a+b '''
+    seq_counts_2 = Counter(seq3)
+    print(seq_counts_2)
+    print(seq_counts + seq_counts_2)
+    print(seq_counts - seq_counts_2)
+
+if __name__ == '__main__':
+    Counter_example()
+
+