Fix Issue #21336: Defeault behavior for resolution property in Timestamps

doc/source/whatsnew/v0.23.2.txt

@@ -75,4 +75,4 @@ Bug Fixes
 
 **Other**
 
--
+- Timestamp resolution returns a :class:`Timedelta` (in nanoseconds) rather than a normal `timedelta` object (in microseconds) (:issue:`21336`)

doc/source/whatsnew/v0.24.0.txt

@@ -193,4 +193,3 @@ Other
 - :meth: `~pandas.io.formats.style.Styler.background_gradient` now takes a ``text_color_threshold`` parameter to automatically lighten the text color based on the luminance of the background color. This improves readability with dark background colors without the need to limit the background colormap range. (:issue:`21258`)
 -
 -
--

pandas/_libs/tslibs/timedeltas.pyx

@@ -795,7 +795,11 @@ cdef class _Timedelta(timedelta):
 
     @property
     def resolution(self):
-        """ return a string representing the lowest resolution that we have """
+        """
+        Return a string representing the lowest resolution that we have.
+        Note that this is nonstandard behavior.
+        To retrieve a timedelta object use the resolution_timedelta property
+        """
 
         self._ensure_components()
         if self._ns:
@@ -813,6 +817,32 @@ cdef class _Timedelta(timedelta):
         else:
             return "D"
 
+    @property
+    def resolution_timedelta(self):
+        """
+        Return a timedelta object (rather than a string)
+        representing the lowest resolution we have.
+        to retrieve a string use the resolution property.
+        """
+
+        self._ensure_components()
+        if self._ns:
+            # At time of writing datetime.timedelta doesn't
+            # support nanoseconds as a keyword argument.
+            return timedelta(microseconds=0.1)
+        elif self._us:
+            return timedelta(microseconds=1)
+        elif self._ms:
+            return timedelta(milliseconds=1)
+        elif self._s:
+            return timedelta(seconds=1)
+        elif self._m:
+            return timedelta(minutes=1)
+        elif self._h:
+            return timedelta(hours=1)
+        else:
+            return timedelta(days=1)
+
     @property
     def nanoseconds(self):
         """

pandas/_libs/tslibs/timestamps.pyx

@@ -400,12 +400,17 @@ cdef class _Timestamp(datetime):
     def asm8(self):
         return np.datetime64(self.value, 'ns')
 
+    @property
+    def resolution(self):
+        """ Return resolution in a native pandas format. """
+        # GH 21336
+        return Timedelta(nanoseconds=1)
+
     def timestamp(self):
         """Return POSIX timestamp as float."""
         # py27 compat, see GH#17329
         return round(self.value / 1e9, 6)
 
-
 # ----------------------------------------------------------------------
 
 # Python front end to C extension type _Timestamp

pandas/tests/scalar/timedelta/test_timedelta.py

@@ -588,3 +588,31 @@ def test_components(self):
         result = s.dt.components
         assert not result.iloc[0].isna().all()
         assert result.iloc[1].isna().all()
+
+    def test_resolution(self):
+        # GH 21344
+        assert Timedelta(nanoseconds=30).resolution == 'N'
+        # Note that datetime.timedelta doesn't offer
+        # finer resolution than microseconds
+        assert Timedelta(nanoseconds=30).resolution_timedelta.resolution == \
+            timedelta(0, 0, 1)
+
+        assert Timedelta(microseconds=30).resolution == 'U'
+        assert Timedelta(microseconds=30).resolution_timedelta.resolution == \
+            timedelta(0, 0, 1)
+
+        assert Timedelta(milliseconds=30).resolution == 'L'
+        assert Timedelta(milliseconds=30).resolution_timedelta.resolution == \
+            timedelta(0, 0, 1)
+
+        assert Timedelta(seconds=30).resolution == 'S'
+        assert Timedelta(seconds=30).resolution_timedelta.resolution == \
+            timedelta(0, 0, 1)
+
+        assert Timedelta(minutes=30).resolution == 'T'
+        assert Timedelta(minutes=30).resolution_timedelta.resolution == \
+            timedelta(0, 0, 1)
+
+        assert Timedelta(hours=2).resolution == 'H'
+        assert Timedelta(hours=2).resolution_timedelta.resolution == \
+            timedelta(0, 0, 1)

pandas/tests/scalar/timestamp/test_timestamp.py

@@ -172,6 +172,11 @@ def test_woy_boundary(self):
                                2005, 1, 1), (2005, 1, 2)]])
         assert (result == [52, 52, 53, 53]).all()
 
+    def test_resolution(self):
+        # GH 21336
+        dt = Timestamp('2100-01-01 00:00:00')
+        assert dt.resolution == Timedelta(nanoseconds=1)
+
 
 class TestTimestampConstructors(object):