wip

Author: MarcoGorelli

pandas/core/interchange/column.py

@@ -202,14 +202,7 @@ def describe_null(self):
             column_null_dtype = ColumnNullType.USE_BITMASK
             null_value = 0
             if ~self._col.isna().any():
-                try:
-                    null, value = _NULL_DESCRIPTION[kind]
-                except KeyError as err:
-                    raise NotImplementedError(
-                        f"Data type {kind} not yet supported"
-                    ) from err
-
-                return null, value
+                return column_null_dtype, None
             return column_null_dtype, null_value
         try:
             null, value = _NULL_DESCRIPTION[kind]

pandas/core/interchange/from_dataframe.py

@@ -300,11 +300,12 @@ def string_column_to_ndarray(col: Column) -> tuple[np.ndarray, Any]:
     if null_kind in (ColumnNullType.USE_BITMASK, ColumnNullType.USE_BYTEMASK):
         assert buffers["validity"], "Validity buffers cannot be empty for masks"
         valid_buff, valid_dtype = buffers["validity"]
-        null_pos = buffer_to_ndarray(
-            valid_buff, valid_dtype, offset=col.offset, length=col.size()
-        )
-        if sentinel_val == 0:
-            null_pos = ~null_pos
+        if valid_buff is not None:
+            null_pos = buffer_to_ndarray(
+                valid_buff, valid_dtype, offset=col.offset, length=col.size()
+            )
+            if sentinel_val == 0:
+                null_pos = ~null_pos
 
     # Assemble the strings from the code units
     str_list: list[None | float | str] = [None] * col.size()
@@ -527,11 +528,12 @@ def set_nulls(
     elif null_kind in (ColumnNullType.USE_BITMASK, ColumnNullType.USE_BYTEMASK):
         assert validity, "Expected to have a validity buffer for the mask"
         valid_buff, valid_dtype = validity
-        null_pos = buffer_to_ndarray(
-            valid_buff, valid_dtype, offset=col.offset, length=col.size()
-        )
-        if sentinel_val == 0:
-            null_pos = ~null_pos
+        if valid_buff is not None:
+            null_pos = buffer_to_ndarray(
+                valid_buff, valid_dtype, offset=col.offset, length=col.size()
+            )
+            if sentinel_val == 0:
+                null_pos = ~null_pos
     elif null_kind in (ColumnNullType.NON_NULLABLE, ColumnNullType.USE_NAN):
         pass
     else: