utils: add new module with random utility functions

calebasse/utils.py

@@ -0,0 +1,25 @@
+from datetime import timedelta, datetime
+
+__EPOCH = datetime(day=5,month=1,year=1970)
+
+def __date_to_datetime(date):
+    return datetime(date.year, date.month, date.day)
+
+def weeks_since_epoch(date):
+    days_since_epoch = (__date_to_datetime(date) - __EPOCH).days
+    return days_since_epoch // 7
+
+def weekday_ranks(date):
+    '''Returns n so that if date occurs on a certain weekday, this is the
+    n-th weekday of the month counting from 0. Also return 4 if this the
+    last suck weekday of the month. '''
+    n = 0
+    month = date.month
+    i = date - timedelta(days=7)
+    while i.month == month:
+        n += 1
+        i = i - timedelta(days=7)
+    if (date+timedelta(days=7)).month != month and n != 4:
+        return n, 4
+    else:
+        return n,