implementation of interval function

arrow/arrow.py

@@ -312,6 +312,49 @@ def span_range(cls, frame, start, end, tz=None, limit=None):
         _range = cls.range(frame, start, end, tz, limit)
         return [r.span(frame) for r in _range]
 
+    @classmethod
+    def interval(cls, frame, start, end, interval=1, tz=None):
+        ''' Returns an array of tuples, each :class:`Arrow <arrow.arrow.Arrow>` objects,
+        representing a series of intervals between two inputs.
+
+        :param frame: the timeframe.  Can be any ``datetime`` property (day, hour, minute...).
+        :param start: A datetime expression, the start of the range.
+        :param end: (optional) A datetime expression, the end of the range.
+        :param interval: (optional) Time interval for the given time frame.
+        :param tz: (optional) A timezone expression.  Defaults to UTC.
+        
+        Supported frame values: year, quarter, month, week, day, hour, minute, second
+
+        Recognized datetime expressions:
+
+            - An :class:`Arrow <arrow.arrow.Arrow>` object.
+            - A ``datetime`` object.
+
+        Recognized timezone expressions:
+
+            - A ``tzinfo`` object.
+            - A ``str`` describing a timezone, similar to 'US/Pacific', or 'Europe/Berlin'.
+            - A ``str`` in ISO-8601 style, as in '+07:00'.
+            - A ``str``, one of the following:  'local', 'utc', 'UTC'.
+
+        Usage:
+
+            >>> start = datetime(2013, 5, 5, 12, 30)
+            >>> end = datetime(2013, 5, 5, 17, 15)
+            >>> for r in arrow.Arrow.interval('hour', start, end, 2):
+            ...     print r
+            ...
+            (<Arrow [2013-05-05T12:00:00+00:00]>, <Arrow [2013-05-05T13:59:59.999999+00:00]>)
+            (<Arrow [2013-05-05T14:00:00+00:00]>, <Arrow [2013-05-05T15:59:59.999999+00:00]>)
+            (<Arrow [2013-05-05T16:00:00+00:00]>, <Arrow [2013-05-05T17:59:59.999999+00:0]>)
+        '''
+        if interval < 1:
+            raise ValueError("interval has to be a positive integer")
+
+        spanRange = cls.span_range(frame,start,end,tz)
+
+        bound = (len(spanRange) // interval) * interval
+        return [ (spanRange[i][0],spanRange[i+ interval - 1][1]) for i in range(0,bound, interval) ]
 
     # representations
 

tests/arrow_tests.py

@@ -923,6 +923,23 @@ def test_aware_tz(self):
             assertEqual(f.tzinfo, tz.gettz('US/Central'))
             assertEqual(c.tzinfo, tz.gettz('US/Central'))
 
+class ArrowIntervalTests(Chai):
+
+    def test_incorrect_input(self):
+        correct = True
+        try:
+            result = arrow.Arrow.interval('month', datetime(2013, 1, 2), datetime(2013, 4, 15),0)
+        except:
+            correct = False
+
+        assertEqual(correct,False)
+
+    def test_correct(self):
+        result = arrow.Arrow.interval('hour', datetime(2013, 5, 5, 12, 30), datetime(2013, 5, 5, 17, 15),2)
+
+        assertEqual(result,[(arrow.Arrow(2013, 5, 5, 12), arrow.Arrow(2013, 5, 5, 13, 59, 59, 999999)),
+            (arrow.Arrow(2013, 5, 5, 14), arrow.Arrow(2013, 5, 5, 15, 59, 59, 999999)),
+            (arrow.Arrow(2013, 5, 5, 16), arrow.Arrow(2013, 5, 5, 17, 59, 59, 999999))])
 
 class ArrowSpanTests(Chai):