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REF: simplify merge code #53808

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Merged
merged 2 commits into from
Jun 23, 2023
Merged

REF: simplify merge code #53808

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7c07ad3
REF: simplify merge code
jbrockmendel Jun 22, 2023
e6f0313
typing
jbrockmendel Jun 23, 2023
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101 changes: 53 additions & 48 deletions pandas/core/reshape/merge.py
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Original file line number Diff line number Diff line change
Expand Up @@ -717,13 +717,23 @@ def __init__(
self.left_on = self.right_on = [cross_col]
self._cross = cross_col

# note this function has side effects
(
self.left_join_keys,
self.right_join_keys,
self.join_names,
left_drop,
right_drop,
) = self._get_merge_keys()

if left_drop:
self.left = self.left._drop_labels_or_levels(left_drop)

if right_drop:
self.right = self.right._drop_labels_or_levels(right_drop)

self._maybe_require_matching_dtypes(self.left_join_keys, self.right_join_keys)
self._validate_tolerance(self.left_join_keys)

# validate the merge keys dtypes. We may need to coerce
# to avoid incompatible dtypes
self._maybe_coerce_merge_keys()
Expand All @@ -732,7 +742,17 @@ def __init__(
# check if columns specified as unique
# are in fact unique.
if validate is not None:
self._validate(validate)
self._validate_validate_kwd(validate)

def _maybe_require_matching_dtypes(
self, left_join_keys: list[ArrayLike], right_join_keys: list[ArrayLike]
) -> None:
# Overridden by AsOfMerge
pass

def _validate_tolerance(self, left_join_keys: list[ArrayLike]) -> None:
# Overridden by AsOfMerge
pass

@final
def _reindex_and_concat(
Expand Down Expand Up @@ -1127,24 +1147,21 @@ def _create_join_index(
index = index.append(Index([fill_value]))
return index.take(indexer)

@final
def _get_merge_keys(
self,
) -> tuple[list[ArrayLike], list[ArrayLike], list[Hashable]]:
) -> tuple[
list[ArrayLike],
list[ArrayLike],
list[Hashable],
list[Hashable],
list[Hashable],
]:
"""
Note: has side effects (copy/delete key columns)

Parameters
----------
left
right
on

Returns
-------
left_keys, right_keys, join_names
left_keys, right_keys, join_names, left_drop, right_drop
"""
# left_keys, right_keys entries can actually be anything listlike
# with a 'dtype' attr
left_keys: list[ArrayLike] = []
right_keys: list[ArrayLike] = []
join_names: list[Hashable] = []
Expand Down Expand Up @@ -1264,13 +1281,7 @@ def _get_merge_keys(
else:
left_keys = [self.left.index._values]

if left_drop:
self.left = self.left._drop_labels_or_levels(left_drop)

if right_drop:
self.right = self.right._drop_labels_or_levels(right_drop)

return left_keys, right_keys, join_names
return left_keys, right_keys, join_names, left_drop, right_drop

@final
def _maybe_coerce_merge_keys(self) -> None:
Expand Down Expand Up @@ -1556,7 +1567,8 @@ def _validate_left_right_on(self, left_on, right_on):

return left_on, right_on

def _validate(self, validate: str) -> None:
@final
def _validate_validate_kwd(self, validate: str) -> None:
# Check uniqueness of each
if self.left_index:
left_unique = self.orig_left.index.is_unique
Expand Down Expand Up @@ -1811,19 +1823,14 @@ def __init__(
def get_result(self, copy: bool | None = True) -> DataFrame:
join_index, left_indexer, right_indexer = self._get_join_info()

llabels, rlabels = _items_overlap_with_suffix(
self.left._info_axis, self.right._info_axis, self.suffixes
)

left_join_indexer: npt.NDArray[np.intp] | None
right_join_indexer: npt.NDArray[np.intp] | None

if self.fill_method == "ffill":
if left_indexer is None:
raise TypeError("left_indexer cannot be None")
left_indexer, right_indexer = cast(np.ndarray, left_indexer), cast(
np.ndarray, right_indexer
)
left_indexer = cast("npt.NDArray[np.intp]", left_indexer)
right_indexer = cast("npt.NDArray[np.intp]", right_indexer)
left_join_indexer = libjoin.ffill_indexer(left_indexer)
right_join_indexer = libjoin.ffill_indexer(right_indexer)
else:
Expand Down Expand Up @@ -1888,6 +1895,18 @@ def __init__(
self.allow_exact_matches = allow_exact_matches
self.direction = direction

# check 'direction' is valid
if self.direction not in ["backward", "forward", "nearest"]:
raise MergeError(f"direction invalid: {self.direction}")

# validate allow_exact_matches
if not is_bool(self.allow_exact_matches):
msg = (
"allow_exact_matches must be boolean, "
f"passed {self.allow_exact_matches}"
)
raise MergeError(msg)

_OrderedMerge.__init__(
self,
left,
Expand Down Expand Up @@ -1975,17 +1994,12 @@ def _validate_left_right_on(self, left_on, right_on):
left_on = self.left_by + list(left_on)
right_on = self.right_by + list(right_on)

# check 'direction' is valid
if self.direction not in ["backward", "forward", "nearest"]:
raise MergeError(f"direction invalid: {self.direction}")

return left_on, right_on

def _get_merge_keys(
self,
) -> tuple[list[ArrayLike], list[ArrayLike], list[Hashable]]:
# note this function has side effects
(left_join_keys, right_join_keys, join_names) = super()._get_merge_keys()
def _maybe_require_matching_dtypes(
self, left_join_keys: list[ArrayLike], right_join_keys: list[ArrayLike]
) -> None:
# TODO: why do we do this for AsOfMerge but not the others?

# validate index types are the same
for i, (lk, rk) in enumerate(zip(left_join_keys, right_join_keys)):
Expand All @@ -2012,6 +2026,7 @@ def _get_merge_keys(
)
raise MergeError(msg)

def _validate_tolerance(self, left_join_keys: list[ArrayLike]) -> None:
# validate tolerance; datetime.timedelta or Timedelta if we have a DTI
if self.tolerance is not None:
if self.left_index:
Expand Down Expand Up @@ -2046,16 +2061,6 @@ def _get_merge_keys(
else:
raise MergeError("key must be integer, timestamp or float")

# validate allow_exact_matches
if not is_bool(self.allow_exact_matches):
msg = (
"allow_exact_matches must be boolean, "
f"passed {self.allow_exact_matches}"
)
raise MergeError(msg)

return left_join_keys, right_join_keys, join_names

def _get_join_indexers(self) -> tuple[npt.NDArray[np.intp], npt.NDArray[np.intp]]:
"""return the join indexers"""

Expand Down