jorisvandenbossche commented on code in PR #13409:
URL: https://github.com/apache/arrow/pull/13409#discussion_r1038133124
##########
python/pyarrow/_dataset.pyx:
##########
@@ -385,6 +416,32 @@ cdef class Dataset(_Weakrefable):
"""The common schema of the full Dataset"""
return pyarrow_wrap_schema(self.dataset.schema())
+ def filter(self, expression):
+ """
+ Apply a row filter to the dataset.
+
+ Parameters
+ ----------
+ expression : Expression
+ The filter that should be applied to the dataset.
+
+ Returns
+ -------
+ Dataset
+ """
+ cdef:
+ Dataset filtered_dataset
+
+ new_filter = expression
+ current_filter = self._scan_options.get("filter")
+ if current_filter is not None and new_filter is not None:
+ new_filter = current_filter & new_filter
Review Comment:
Ah, that was not clear to me (and should also be documented then).
Personally I would also not expect such behaviour, since that seems to go
against my expectation for composable method chains (based on my experience
with pandas, and from a quick check also not what dplyr filter does when
passing no filter), where each method does something in addition to the
previous one, and not undo it.
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