ENH: add unit, as_unit to dt accessor

doc/source/reference/series.rst

@@ -326,6 +326,7 @@ Datetime properties
    Series.dt.days_in_month
    Series.dt.tz
    Series.dt.freq
+   Series.dt.unit
 
 Datetime methods
 ^^^^^^^^^^^^^^^^
@@ -346,6 +347,7 @@ Datetime methods
    Series.dt.ceil
    Series.dt.month_name
    Series.dt.day_name
+   Series.dt.as_unit
 
 Period properties
 ^^^^^^^^^^^^^^^^^
@@ -370,6 +372,7 @@ Timedelta properties
    Series.dt.microseconds
    Series.dt.nanoseconds
    Series.dt.components
+   Series.dt.unit
 
 Timedelta methods
 ^^^^^^^^^^^^^^^^^
@@ -380,6 +383,7 @@ Timedelta methods
 
    Series.dt.to_pytimedelta
    Series.dt.total_seconds
+   Series.dt.as_unit
 
 
 .. _api.series.str:

doc/source/whatsnew/v2.0.0.rst

@@ -289,6 +289,7 @@ Other enhancements
 - Improved error message in :func:`to_datetime` for non-ISO8601 formats, informing users about the position of the first error (:issue:`50361`)
 - Improved error message when trying to align :class:`DataFrame` objects (for example, in :func:`DataFrame.compare`) to clarify that "identically labelled" refers to both index and columns (:issue:`50083`)
 - Added :meth:`DatetimeIndex.as_unit` and :meth:`TimedeltaIndex.as_unit` to convert to different resolutions; supported resolutions are "s", "ms", "us", and "ns" (:issue:`50616`)
+- Added :meth:`Series.dt.unit` and :meth:`Series.dt.as_unit` to convert to different resolutions; supported resolutions are "s", "ms", "us", and "ns" (:issue:`51223`)
 - Added new argument ``dtype`` to :func:`read_sql` to be consistent with :func:`read_sql_query` (:issue:`50797`)
 -
 

pandas/core/arrays/datetimes.py

@@ -228,7 +228,9 @@ def _scalar_type(self) -> type[Timestamp]:
         "nanosecond",
     ]
     _other_ops: list[str] = ["date", "time", "timetz"]
-    _datetimelike_ops: list[str] = _field_ops + _object_ops + _bool_ops + _other_ops
+    _datetimelike_ops: list[str] = (
+        _field_ops + _object_ops + _bool_ops + _other_ops + ["unit"]
+    )
     _datetimelike_methods: list[str] = [
         "to_period",
         "tz_localize",
@@ -240,6 +242,7 @@ def _scalar_type(self) -> type[Timestamp]:
         "ceil",
         "month_name",
         "day_name",
+        "as_unit",
     ]
 
     # ndim is inherited from ExtensionArray, must exist to ensure

pandas/core/arrays/timedeltas.py

@@ -137,13 +137,14 @@ def _scalar_type(self) -> type[Timedelta]:
     _bool_ops: list[str] = []
     _object_ops: list[str] = ["freq"]
     _field_ops: list[str] = ["days", "seconds", "microseconds", "nanoseconds"]
-    _datetimelike_ops: list[str] = _field_ops + _object_ops + _bool_ops
+    _datetimelike_ops: list[str] = _field_ops + _object_ops + _bool_ops + ["unit"]
     _datetimelike_methods: list[str] = [
         "to_pytimedelta",
         "total_seconds",
         "round",
         "floor",
         "ceil",
+        "as_unit",
     ]
 
     # Note: ndim must be defined to ensure NaT.__richcmp__(TimedeltaArray)

pandas/core/indexes/accessors.py

@@ -140,10 +140,14 @@ def _delegate_method(self, name, *args, **kwargs):
 
 
 @delegate_names(
-    delegate=DatetimeArray, accessors=DatetimeArray._datetimelike_ops, typ="property"
+    delegate=DatetimeArray,
+    accessors=DatetimeArray._datetimelike_ops + ["unit"],
+    typ="property",
 )
 @delegate_names(
-    delegate=DatetimeArray, accessors=DatetimeArray._datetimelike_methods, typ="method"
+    delegate=DatetimeArray,
+    accessors=DatetimeArray._datetimelike_methods + ["as_unit"],
+    typ="method",
 )
 class DatetimeProperties(Properties):
     """

pandas/tests/series/accessors/test_cat_accessor.py

@@ -167,6 +167,7 @@ def test_dt_accessor_api_for_categorical(self, idx):
             ("floor", ("D",), {}),
             ("ceil", ("D",), {}),
             ("asfreq", ("D",), {}),
+            ("as_unit", ("s"), {}),
         ]
         if idx.dtype == "M8[ns]":
             # exclude dt64tz since that is already localized and would raise

pandas/tests/series/accessors/test_dt_accessor.py

@@ -55,6 +55,7 @@
     "day_name",
     "month_name",
     "isocalendar",
+    "as_unit",
 ]
 ok_for_td = TimedeltaArray._datetimelike_ops
 ok_for_td_methods = [
@@ -64,6 +65,7 @@
     "round",
     "floor",
     "ceil",
+    "as_unit",
 ]