BUG: TimedeltaIndex.__repr__ with non-nano and round values

doc/source/whatsnew/v2.2.0.rst

@@ -296,7 +296,7 @@ Datetimelike
 
 Timedelta
 ^^^^^^^^^
--
+- Bug in rendering (``__repr__``) of :class:`TimedeltaIndex` and :class:`Series` with timedelta64 values with non-nanosecond resolution entries that are all multiples of 24 hours failing to use the compact representation used in the nanosecond cases (:issue:`??`)
 -
 
 Timezones

pandas/core/arrays/datetimelike.py

@@ -41,6 +41,7 @@
     iNaT,
     ints_to_pydatetime,
     ints_to_pytimedelta,
+    periods_per_day,
     to_offset,
 )
 from pandas._libs.tslibs.fields import (
@@ -2312,6 +2313,31 @@ def interpolate(
             return self
         return type(self)._simple_new(out_data, dtype=self.dtype)
 
+    # --------------------------------------------------------------
+    # Unsorted
+
+    @property
+    def _is_dates_only(self) -> bool:
+        """
+        Check if we are round times at midnight (and no timezone), which will
+        be given a more compact __repr__ than other cases. For TimedeltaArray
+        we are checking for multiples of 24H.
+        """
+        if not lib.is_np_dtype(self.dtype):
+            # i.e. we have a timezone
+            return False
+
+        values_int = self.asi8
+        consider_values = values_int != iNaT
+        dtype = cast(np.dtype, self.dtype)  # since we checked tz above
+        reso = get_unit_from_dtype(dtype)
+        ppd = periods_per_day(reso)
+
+        # TODO: can we reuse is_date_array_normalized?  would need a skipna kwd
+        #  (first attempt at this was less performant than this implementation)
+        even_days = np.logical_and(consider_values, values_int % ppd != 0).sum() == 0
+        return even_days
+
 
 # -------------------------------------------------------------------
 # Shared Constructor Helpers

pandas/io/formats/format.py

@@ -106,7 +106,6 @@
         SequenceNotStr,
         StorageOptions,
         WriteBuffer,
-        npt,
     )
 
     from pandas import (
@@ -1814,15 +1813,7 @@ def get_format_timedelta64(
 
     If box, then show the return in quotes
     """
-    values_int = values.view(np.int64)
-    values_int = cast("npt.NDArray[np.int64]", values_int)
-
-    consider_values = values_int != iNaT
-
-    one_day_nanos = 86400 * 10**9
-    not_midnight = values_int % one_day_nanos != 0
-    both = np.logical_and(consider_values, not_midnight)
-    even_days = both.sum() == 0
+    even_days = values._is_dates_only
 
     if even_days:
         format = None

pandas/tests/indexes/timedeltas/test_formats.py

@@ -8,6 +8,17 @@
 
 
 class TestTimedeltaIndexRendering:
+    def test_repr_round_days_non_nano(self):
+        # we should get "1 days", not "1 days 00:00:00" with non-nano
+        tdi = TimedeltaIndex(["1 days"], freq="D").as_unit("s")
+        result = repr(tdi)
+        expected = "TimedeltaIndex(['1 days'], dtype='timedelta64[s]', freq='D')"
+        assert result == expected
+
+        result2 = repr(Series(tdi))
+        expected2 = "0   1 days\ndtype: timedelta64[s]"
+        assert result2 == expected2
+
     @pytest.mark.parametrize("method", ["__repr__", "__str__"])
     def test_representation(self, method):
         idx1 = TimedeltaIndex([], freq="D")