Implement map also for Pandas 2.0.2

Implement `map` for PintArrays also only with Pandas 2.0.2 interfaces.

Signed-off-by: Michael Tiemann <[email protected]>

Author: MichaelTiemannOSC

CHANGES

@@ -5,7 +5,8 @@ pint-pandas Changelog
 ----------------
 
 <<<<<<< HEAD
-- Support for Pandas version 2.1.0 (including dtype-preserving `PintArray.map`) #196
+- Support for Pandas version 2.1.0. #196
+- Support for dtype-preserving `PintArray.map` for both Pandas 2.0.2 and Pandas 2.1. #196
 - Support for <NA> values in columns with integer magnitudes
 - Support for magnitudes of any type, such as complex128 or tuples #146
 - Support for pandas 2.0, allowing `.cumsum, .cummax, .cummin` methods for `Series` and `DataFrame`. #186

pint_pandas/pint_array.py

@@ -844,9 +844,14 @@ def map(self, mapper, na_action=None):
         If mapper is a function, operate on the magnitudes of the array and
 
         """
-        from pandas.core.algorithms import map_array
+        if pandas_version_info < (2, 1):
+            ser = pd.Series(self._to_array_of_quantity())
+            arr = ser.map(mapper, na_action).values
+        else:
+            from pandas.core.algorithms import map_array
+
+            arr = map_array(self, mapper, na_action)
 
-        arr = map_array(self, mapper, na_action)
         master_scalar = None
         try:
             master_scalar = next(i for i in arr if hasattr(i, "units"))