CLN/REF: indexing typing, prune unreachable branches (#27351)

Author: jbrockmendel

pandas/core/frame.py

@@ -2889,11 +2889,11 @@ def _set_value(self, index, col, value, takeable=False):
 
     _set_value.__doc__ = set_value.__doc__
 
-    def _ixs(self, i, axis=0):
+    def _ixs(self, i: int, axis: int = 0):
         """
         Parameters
         ----------
-        i : int, slice, or sequence of integers
+        i : int
         axis : int
 
         Notes
@@ -2902,59 +2902,40 @@ def _ixs(self, i, axis=0):
         """
         # irow
         if axis == 0:
-            if isinstance(i, slice):
-                return self[i]
-            else:
-                label = self.index[i]
-                if isinstance(label, Index):
-                    # a location index by definition
-                    result = self.take(i, axis=axis)
-                    copy = True
-                else:
-                    new_values = self._data.fast_xs(i)
-                    if is_scalar(new_values):
-                        return new_values
-
-                    # if we are a copy, mark as such
-                    copy = (
-                        isinstance(new_values, np.ndarray) and new_values.base is None
-                    )
-                    result = self._constructor_sliced(
-                        new_values,
-                        index=self.columns,
-                        name=self.index[i],
-                        dtype=new_values.dtype,
-                    )
-                result._set_is_copy(self, copy=copy)
-                return result
+            label = self.index[i]
+            new_values = self._data.fast_xs(i)
+            if is_scalar(new_values):
+                return new_values
+
+            # if we are a copy, mark as such
+            copy = isinstance(new_values, np.ndarray) and new_values.base is None
+            result = self._constructor_sliced(
+                new_values,
+                index=self.columns,
+                name=self.index[i],
+                dtype=new_values.dtype,
+            )
+            result._set_is_copy(self, copy=copy)
+            return result
 
         # icol
         else:
             label = self.columns[i]
-            if isinstance(i, slice):
-                # need to return view
-                lab_slice = slice(label[0], label[-1])
-                return self.loc[:, lab_slice]
-            else:
-                if isinstance(label, Index):
-                    return self.take(i, axis=1)
 
-                index_len = len(self.index)
+            # if the values returned are not the same length
+            # as the index (iow a not found value), iget returns
+            # a 0-len ndarray. This is effectively catching
+            # a numpy error (as numpy should really raise)
+            values = self._data.iget(i)
 
-                # if the values returned are not the same length
-                # as the index (iow a not found value), iget returns
-                # a 0-len ndarray. This is effectively catching
-                # a numpy error (as numpy should really raise)
-                values = self._data.iget(i)
+            if len(self.index) and not len(values):
+                values = np.array([np.nan] * len(self.index), dtype=object)
+            result = self._box_col_values(values, label)
 
-                if index_len and not len(values):
-                    values = np.array([np.nan] * index_len, dtype=object)
-                result = self._box_col_values(values, label)
+            # this is a cached value, mark it so
+            result._set_as_cached(label, self)
 
-                # this is a cached value, mark it so
-                result._set_as_cached(label, self)
-
-                return result
+            return result
 
     def __getitem__(self, key):
         key = lib.item_from_zerodim(key)

pandas/core/generic.py

@@ -3495,7 +3495,7 @@ def __delitem__(self, key):
         deleted = False
 
         maybe_shortcut = False
-        if hasattr(self, "columns") and isinstance(self.columns, MultiIndex):
+        if self.ndim == 2 and isinstance(self.columns, MultiIndex):
             try:
                 maybe_shortcut = key not in self.columns._engine
             except TypeError:
@@ -5231,9 +5231,6 @@ def _dir_additions(self):
         }
         return super()._dir_additions().union(additions)
 
-    # ----------------------------------------------------------------------
-    # Getting and setting elements
-
     # ----------------------------------------------------------------------
     # Consolidation of internals