ENH: add iso-format support to to_timedelta (#21877) (#21933)

Author: fjdiod

doc/source/whatsnew/v0.24.0.txt

@@ -119,6 +119,7 @@ Other Enhancements
 - :meth:`Series.nlargest`, :meth:`Series.nsmallest`, :meth:`DataFrame.nlargest`, and :meth:`DataFrame.nsmallest` now accept the value ``"all"`` for the ``keep`` argument. This keeps all ties for the nth largest/smallest value (:issue:`16818`)
 - :class:`IntervalIndex` has gained the :meth:`~IntervalIndex.set_closed` method to change the existing ``closed`` value (:issue:`21670`)
 - :func:`~DataFrame.to_csv` and :func:`~DataFrame.to_json` now support ``compression='infer'`` to infer compression based on filename (:issue:`15008`)
+- :func:`to_timedelta` now supports iso-formated timedelta strings (:issue:`21877`)
 -
 
 .. _whatsnew_0240.api_breaking:

pandas/_libs/tslibs/timedeltas.pyx

@@ -183,7 +183,11 @@ cpdef convert_to_timedelta64(object ts, object unit):
  ts = cast_from_unit(ts, unit)
  ts = np.timedelta64(ts)
  elif is_string_object(ts):
- ts = np.timedelta64(parse_timedelta_string(ts))
+ if len(ts) > 0 and ts[0] == 'P':
+ ts = parse_iso_format_string(ts)
+ else:
+ ts = parse_timedelta_string(ts)
+ ts = np.timedelta64(ts)
  elif hasattr(ts, 'delta'):
  ts = np.timedelta64(delta_to_nanoseconds(ts), 'ns')
 

pandas/tests/indexes/timedeltas/test_construction.py

@@ -44,6 +44,13 @@ def test_constructor(self):
  tm.assert_index_equal(TimedeltaIndex([400, 450, 1200], unit='ms'),
  expected)
 
+ def test_constructor_iso(self):
+ # GH #21877
+ expected = timedelta_range('1s', periods=9, freq='s')
+ durations = ['P0DT0H0M{}S'.format(i) for i in range(1, 10)]
+ result = to_timedelta(durations)
+ tm.assert_index_equal(result, expected)
+
  def test_constructor_coverage(self):
  rng = timedelta_range('1 days', periods=10.5)
  exp = timedelta_range('1 days', periods=10)

pandas/tests/scalar/timedelta/test_timedelta.py

@@ -233,6 +233,11 @@ def check(value):
  assert tup.microseconds == 999
  assert tup.nanoseconds == 0
 
+ def test_iso_conversion(self):
+ # GH #21877
+ expected = Timedelta(1, unit='s')
+ assert to_timedelta('P0DT0H0M1S') == expected
+
  def test_nat_converters(self):
  assert to_timedelta('nat', box=False).astype('int64') == iNaT
  assert to_timedelta('nan', box=False).astype('int64') == iNaT