DOC: Update documentation for date_range(), bdate_range(), and interv…

…al_range() to include timedelta as a possible data type for the freq parameter (#48631)

* Update documentation for date_range(), bdate_range(), and interval_range() to include timedelta as a possible data type for the freq parameter

* Add test case for date_range construction using datetime.timedelta

pandas/core/indexes/datetimes.py

@@ -966,7 +966,7 @@ def date_range(
         Right bound for generating dates.
     periods : int, optional
         Number of periods to generate.
-    freq : str or DateOffset, default 'D'
+    freq : str, datetime.timedelta, or DateOffset, default 'D'
         Frequency strings can have multiples, e.g. '5H'. See
         :ref:`here <timeseries.offset_aliases>` for a list of
         frequency aliases.
@@ -1163,7 +1163,7 @@ def bdate_range(
         Right bound for generating dates.
     periods : int, default None
         Number of periods to generate.
-    freq : str or DateOffset, default 'B' (business daily)
+    freq : str, datetime.timedelta, or DateOffset, default 'B' (business daily)
         Frequency strings can have multiples, e.g. '5H'.
     tz : str or None
         Time zone name for returning localized DatetimeIndex, for example

pandas/core/indexes/interval.py

@@ -969,7 +969,7 @@ def interval_range(
         Right bound for generating intervals.
     periods : int, default None
         Number of periods to generate.
-    freq : numeric, str, or DateOffset, default None
+    freq : numeric, str, datetime.timedelta, or DateOffset, default None
         The length of each interval. Must be consistent with the type of start
         and end, e.g. 2 for numeric, or '5H' for datetime-like.  Default is 1
         for numeric and 'D' for datetime-like.

pandas/tests/indexes/datetimes/test_date_range.py

@@ -432,6 +432,13 @@ def test_date_range_businesshour(self):
         rng = date_range("2014-07-04 09:00", "2014-07-08 16:00", freq="BH")
         tm.assert_index_equal(idx, rng)
 
+    def test_date_range_timedelta(self):
+        start = "2020-01-01"
+        end = "2020-01-11"
+        rng1 = date_range(start, end, freq="3D")
+        rng2 = date_range(start, end, freq=timedelta(days=3))
+        tm.assert_index_equal(rng1, rng2)
+
     def test_range_misspecified(self):
         # GH #1095
         msg = (