REF: share check_value_size (pandas-dev#40009)

Author: jbrockmendel

pandas/core/arrays/_mixins.py

@@ -23,7 +23,6 @@
 from pandas.util._validators import validate_fillna_kwargs
 
 from pandas.core.dtypes.common import is_dtype_equal
-from pandas.core.dtypes.inference import is_array_like
 from pandas.core.dtypes.missing import array_equivalent
 
 from pandas.core import missing
@@ -275,15 +274,7 @@ def fillna(
         value, method = validate_fillna_kwargs(value, method)
 
         mask = self.isna()
-
-        # TODO: share this with EA base class implementation
-        if is_array_like(value):
-            if len(value) != len(self):
-                raise ValueError(
-                    f"Length of 'value' does not match. Got ({len(value)}) "
-                    f" expected {len(self)}"
-                )
-            value = value[mask]
+        value = missing.check_value_size(value, mask, len(self))
 
         if mask.any():
             if method is not None:

pandas/core/arrays/base.py

@@ -44,7 +44,6 @@
 
 from pandas.core.dtypes.cast import maybe_cast_to_extension_array
 from pandas.core.dtypes.common import (
-    is_array_like,
     is_dtype_equal,
     is_list_like,
     is_scalar,
@@ -58,13 +57,15 @@
 )
 from pandas.core.dtypes.missing import isna
 
-from pandas.core import ops
+from pandas.core import (
+    missing,
+    ops,
+)
 from pandas.core.algorithms import (
     factorize_array,
     isin,
     unique,
 )
-from pandas.core.missing import get_fill_func
 from pandas.core.sorting import (
     nargminmax,
     nargsort,
@@ -696,18 +697,11 @@ def fillna(self, value=None, method=None, limit=None):
         value, method = validate_fillna_kwargs(value, method)
 
         mask = self.isna()
-
-        if is_array_like(value):
-            if len(value) != len(self):
-                raise ValueError(
-                    f"Length of 'value' does not match. Got ({len(value)}) "
-                    f"expected {len(self)}"
-                )
-            value = value[mask]
+        value = missing.check_value_size(value, mask, len(self))
 
         if mask.any():
             if method is not None:
-                func = get_fill_func(method)
+                func = missing.get_fill_func(method)
                 new_values = func(self.astype(object), limit=limit, mask=mask)
                 new_values = self._from_sequence(new_values, dtype=self.dtype)
             else:

pandas/core/arrays/string_arrow.py

@@ -33,13 +33,13 @@
     is_integer_dtype,
     is_scalar,
 )
+from pandas.core import missing
 from pandas.core.arraylike import OpsMixin
 from pandas.core.arrays.base import ExtensionArray
 from pandas.core.indexers import (
     check_array_indexer,
     validate_indices,
 )
-from pandas.core.missing import get_fill_func
 
 try:
     import pyarrow as pa
@@ -380,18 +380,11 @@ def fillna(self, value=None, method=None, limit=None):
         value, method = validate_fillna_kwargs(value, method)
 
         mask = self.isna()
-
-        if is_array_like(value):
-            if len(value) != len(self):
-                raise ValueError(
-                    f"Length of 'value' does not match. Got ({len(value)}) "
-                    f"expected {len(self)}"
-                )
-            value = value[mask]
+        value = missing.check_value_size(value, mask, len(self))
 
         if mask.any():
             if method is not None:
-                func = get_fill_func(method)
+                func = missing.get_fill_func(method)
                 new_values = func(self.to_numpy(object), limit=limit, mask=mask)
                 new_values = self._from_sequence(new_values)
             else:

pandas/core/missing.py

@@ -29,6 +29,7 @@
 from pandas.core.dtypes.cast import infer_dtype_from
 from pandas.core.dtypes.common import (
     ensure_float64,
+    is_array_like,
     is_integer_dtype,
     is_numeric_v_string_like,
     needs_i8_conversion,
@@ -39,6 +40,21 @@
     from pandas import Index
 
 
+def check_value_size(value, mask: np.ndarray, length: int):
+    """
+    Validate the size of the values passed to ExtensionArray.fillna.
+    """
+    if is_array_like(value):
+        if len(value) != length:
+            raise ValueError(
+                f"Length of 'value' does not match. Got ({len(value)}) "
+                f" expected {length}"
+            )
+        value = value[mask]
+
+    return value
+
+
 def mask_missing(arr: ArrayLike, values_to_mask) -> np.ndarray:
     """
     Return a masking array of same size/shape as arr