AlenkaF commented on code in PR #49355:
URL: https://github.com/apache/arrow/pull/49355#discussion_r2894392453
##########
docs/source/python/dataset.rst:
##########
@@ -569,6 +569,29 @@ calculate the average of a column without loading the
entire column into memory:
... count += batch.num_rows
>>> mean_a = col2_sum/count
+The ``filter`` argument of :meth:`Dataset.to_batches` (and
:func:`~Dataset.to_table`)
+expects a boolean :class:`~pyarrow.dataset.Expression`, which can be
constructed using
+:func:`pyarrow.dataset.field` and its operator overloads. However, if you
already have
+filters in the DNF (Disjunctive Normal Form) list-of-tuples format accepted by
+:class:`pyarrow.parquet.ParquetDataset`, you can convert them to an
``Expression``
+using :func:`pyarrow.parquet.filters_to_expression`:
+
+.. code-block:: python
+
+ >>> import pyarrow.parquet as pq
+ >>> import pyarrow.compute as pc
+ >>> dataset = ds.dataset(base / "parquet_dataset", format="parquet")
Review Comment:
This part also doesn't have to be run again. We could print the table
though, so it would be more clear what the `a_sum` result means?
```suggestion
>>> dataset.to_table(columns=['a'])
```
##########
docs/source/python/dataset.rst:
##########
@@ -569,6 +569,29 @@ calculate the average of a column without loading the
entire column into memory:
... count += batch.num_rows
>>> mean_a = col2_sum/count
+The ``filter`` argument of :meth:`Dataset.to_batches` (and
:func:`~Dataset.to_table`)
+expects a boolean :class:`~pyarrow.dataset.Expression`, which can be
constructed using
+:func:`pyarrow.dataset.field` and its operator overloads. However, if you
already have
+filters in the DNF (Disjunctive Normal Form) list-of-tuples format accepted by
+:class:`pyarrow.parquet.ParquetDataset`, you can convert them to an
``Expression``
+using :func:`pyarrow.parquet.filters_to_expression`:
+
+.. code-block:: python
+
+ >>> import pyarrow.parquet as pq
+ >>> import pyarrow.compute as pc
Review Comment:
```suggestion
```
These can be removed as we have imported them above. IMHO the code is
clearer if we do not repeat the imports.
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