Update managers.py

When a loc indexer goes to create a fresh array to hold values from an Extension Array, it makes the array allocation based on the na_value of the EA, but that na_value may be smaller than the size of the things that the EA can hold (such as complex128).  Note that np.nan is itself a legitimate complex128 value.

If the allocated array cannot hold the values from the block manager, and if the EA is not immutable, it will try a second strategy of allocating an array based on the dtype of the values of the blocks.  If the blocks hold complex numbers, the array will be properly sized.

This should close pandas-dev#54445.

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

Author: MichaelTiemannOSC

pandas/core/internals/managers.py

@@ -983,11 +983,18 @@ def fast_xs(self, loc: int) -> SingleBlockManager:
             )
             result = ensure_wrapped_if_datetimelike(result)
 
-        for blk in self.blocks:
-            # Such assignment may incorrectly coerce NaT to None
-            # result[blk.mgr_locs] = blk._slice((slice(None), loc))
-            for i, rl in enumerate(blk.mgr_locs):
-                result[rl] = blk.iget((i, loc))
+        try:
+            for blk in self.blocks:
+                # Such assignment may incorrectly coerce NaT to None
+                # result[blk.mgr_locs] = blk._slice((slice(None), loc))
+                for i, rl in enumerate(blk.mgr_locs):
+                    result[rl] = blk.iget((i, loc))
+        except TypeError:
+            if isinstance(dtype, ExtensionDtype) and not immutable_ea:
+                values = [v[loc] for v in self.arrays]
+                result = cls._from_sequence(values, dtype)
+            else:
+                raise TypeError
 
         if immutable_ea:
             dtype = cast(ExtensionDtype, dtype)