REF: IntervalIndex.intersection match pattern in other intersection methods (#38190)

Author: jbrockmendel

pandas/core/indexes/base.py

@@ -2828,8 +2828,8 @@ def intersection(self, other, sort=False):
 
  if not is_dtype_equal(self.dtype, other.dtype):
  dtype = find_common_type([self.dtype, other.dtype])
- this = self.astype(dtype)
- other = other.astype(dtype)
+ this = self.astype(dtype, copy=False)
+ other = other.astype(dtype, copy=False)
  return this.intersection(other, sort=sort)
 
  result = self._intersection(other, sort=sort)

pandas/core/indexes/interval.py

@@ -967,9 +967,20 @@ def intersection(self, other, sort=False) -> Index:
  self._assert_can_do_setop(other)
  other, _ = self._convert_can_do_setop(other)
 
+ if self.equals(other) and not self.has_duplicates:
+ return self._get_reconciled_name_object(other)
+
  if not isinstance(other, IntervalIndex):
  return self.astype(object).intersection(other)
 
+ result = self._intersection(other, sort=sort)
+ return self._wrap_setop_result(other, result)
+
+ def _intersection(self, other, sort):
+ """
+ intersection specialized to the case with matching dtypes.
+ """
+ # For IntervalIndex we also know other.closed == self.closed
  if self.left.is_unique and self.right.is_unique:
  taken = self._intersection_unique(other)
  elif other.left.is_unique and other.right.is_unique and self.isna().sum() <= 1:
@@ -983,7 +994,7 @@ def intersection(self, other, sort=False) -> Index:
  if sort is None:
  taken = taken.sort_values()
 
- return self._wrap_setop_result(other, taken)
+ return taken
 
  def _intersection_unique(self, other: "IntervalIndex") -> "IntervalIndex":
  """

pandas/core/indexes/multi.py

@@ -3723,7 +3723,7 @@ def _convert_can_do_setop(self, other):
  try:
  other = MultiIndex.from_tuples(other)
  except (ValueError, TypeError) as err:
- # ValueError raised by tupels_to_object_array if we
+ # ValueError raised by tuples_to_object_array if we
  # have non-object dtype
  raise TypeError(msg) from err
  else: