REF: re-use sequence_to_datetimes in try_datetime (#40191)

Author: jbrockmendel

pandas/core/arrays/datetimes.py

@@ -1905,13 +1905,16 @@ def std(
 
 
 def sequence_to_datetimes(
-    data, allow_object: bool = False
+    data, allow_object: bool = False, require_iso8601: bool = False
 ) -> Union[np.ndarray, DatetimeArray]:
     """
     Parse/convert the passed data to either DatetimeArray or np.ndarray[object].
     """
     result, tz, freq = sequence_to_dt64ns(
-        data, allow_object=allow_object, allow_mixed=True
+        data,
+        allow_object=allow_object,
+        allow_mixed=True,
+        require_iso8601=require_iso8601,
     )
     if result.dtype == object:
         return result
@@ -1932,6 +1935,7 @@ def sequence_to_dt64ns(
     *,
     allow_object: bool = False,
     allow_mixed: bool = False,
+    require_iso8601: bool = False,
 ):
     """
     Parameters
@@ -1949,6 +1953,8 @@ def sequence_to_dt64ns(
         data contains more than one timezone.
     allow_mixed : bool, default False
         Interpret integers as timestamps when datetime objects are also present.
+    require_iso8601 : bool, default False
+        Only consider ISO-8601 formats when parsing strings.
 
     Returns
     -------
@@ -2017,6 +2023,7 @@ def sequence_to_dt64ns(
                 yearfirst=yearfirst,
                 allow_object=allow_object,
                 allow_mixed=allow_mixed,
+                require_iso8601=require_iso8601,
             )
             if tz and inferred_tz:
                 #  two timezones: convert to intended from base UTC repr
@@ -2083,8 +2090,8 @@ def objects_to_datetime64ns(
     yearfirst,
     utc=False,
     errors="raise",
-    require_iso8601=False,
-    allow_object=False,
+    require_iso8601: bool = False,
+    allow_object: bool = False,
     allow_mixed: bool = False,
 ):
     """

pandas/core/dtypes/cast.py

@@ -1519,40 +1519,25 @@ def maybe_infer_to_datetimelike(value: Union[np.ndarray, List]):
     def try_datetime(v: np.ndarray) -> ArrayLike:
         # Coerce to datetime64, datetime64tz, or in corner cases
         #  object[datetimes]
-        from pandas.core.arrays.datetimes import (
-            DatetimeArray,
-            objects_to_datetime64ns,
-            tz_to_dtype,
-        )
+        from pandas.core.arrays.datetimes import sequence_to_datetimes
 
         try:
             # GH#19671 we pass require_iso8601 to be relatively strict
             #  when parsing strings.
-            vals, tz = objects_to_datetime64ns(
-                v,
-                require_iso8601=True,
-                dayfirst=False,
-                yearfirst=False,
-                allow_object=True,
-            )
+            dta = sequence_to_datetimes(v, require_iso8601=True, allow_object=True)
         except (ValueError, TypeError):
             # e.g. <class 'numpy.timedelta64'> is not convertible to datetime
             return v.reshape(shape)
         else:
-            # we might have a sequence of the same-datetimes with tz's
-            # if so coerce to a DatetimeIndex; if they are not the same,
-            # then these stay as object dtype, xref GH#19671
-
-            if vals.dtype == object:
+            if dta.dtype == object or dta.tz is None:
+                # GH#19671 if we have mixed timezones we may have object-dtype
+                #  here.
                 # This is reachable bc allow_object=True, means we cast things
                 #  to mixed-tz datetime objects (mostly).  Only 1 test
                 #  relies on this behavior, see GH#40111
-                return vals.reshape(shape)
-
-            dta = DatetimeArray._simple_new(vals.view("M8[ns]"), dtype=tz_to_dtype(tz))
-            if dta.tz is None:
-                # TODO(EA2D): conditional reshape kludge unnecessary with 2D EAs
-                return dta._ndarray.reshape(shape)
+                # FIXME: conditional reshape is kludgy
+                return np.asarray(dta).reshape(shape)
+            # otherwise we have dt64tz
             return dta
 
     def try_timedelta(v: np.ndarray) -> np.ndarray: