### What changes were proposed in this pull request?
Prevent unnecessary copies of data during conversion from Arrow to Pandas.
### Why are the changes needed?
During conversion of pyarrow data to Pandas, columns are checked for timestamp types and then modified to correct for local timezone. If the data contains no timestamp types, then unnecessary copies of the data can be made. This is most prevalent when checking columns of a pandas DataFrame where each series is assigned back to the DataFrame, regardless if it had timestamps. See https://www.mail-archive.com/devarrow.apache.org/msg17008.html and ARROW-7596 for discussion.
### Does this PR introduce any user-facing change?
No
### How was this patch tested?
Existing tests
Closes#27358 from BryanCutler/pyspark-pandas-timestamp-copy-fix-SPARK-30640.
Authored-by: Bryan Cutler <cutlerb@gmail.com>
Signed-off-by: Bryan Cutler <cutlerb@gmail.com>
### What changes were proposed in this pull request?
In the PR, I propose to remove the SQL config `spark.sql.execution.pandas.respectSessionTimeZone` which has been deprecated since Spark 2.3.
### Why are the changes needed?
To improve code maintainability.
### Does this PR introduce any user-facing change?
Yes.
### How was this patch tested?
by running python tests, https://spark.apache.org/docs/latest/building-spark.html#pyspark-tests-with-maven-or-sbtCloses#27218 from MaxGekk/remove-respectSessionTimeZone.
Authored-by: Maxim Gekk <max.gekk@gmail.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
### What changes were proposed in this pull request?
This is a followup of https://github.com/apache/spark/pull/27109. It should match the parameter lists in `createDataFrame`.
### Why are the changes needed?
To pass parameters supposed to pass.
### Does this PR introduce any user-facing change?
No (it's only in master)
### How was this patch tested?
Manually tested and existing tests should cover.
Closes#27225 from HyukjinKwon/SPARK-30434-followup.
Authored-by: HyukjinKwon <gurwls223@apache.org>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
### What changes were proposed in this pull request?
This PR proposes to move pandas related functionalities into pandas package. Namely:
```bash
pyspark/sql/pandas
├── __init__.py
├── conversion.py # Conversion between pandas <> PySpark DataFrames
├── functions.py # pandas_udf
├── group_ops.py # Grouped UDF / Cogrouped UDF + groupby.apply, groupby.cogroup.apply
├── map_ops.py # Map Iter UDF + mapInPandas
├── serializers.py # pandas <> PyArrow serializers
├── types.py # Type utils between pandas <> PyArrow
└── utils.py # Version requirement checks
```
In order to separately locate `groupby.apply`, `groupby.cogroup.apply`, `mapInPandas`, `toPandas`, and `createDataFrame(pdf)` under `pandas` sub-package, I had to use a mix-in approach which Scala side uses often by `trait`, and also pandas itself uses this approach (see `IndexOpsMixin` as an example) to group related functionalities. Currently, you can think it's like Scala's self typed trait. See the structure below:
```python
class PandasMapOpsMixin(object):
def mapInPandas(self, ...):
...
return ...
# other Pandas <> PySpark APIs
```
```python
class DataFrame(PandasMapOpsMixin):
# other DataFrame APIs equivalent to Scala side.
```
Yes, This is a big PR but they are mostly just moving around except one case `createDataFrame` which I had to split the methods.
### Why are the changes needed?
There are pandas functionalities here and there and I myself gets lost where it was. Also, when you have to make a change commonly for all of pandas related features, it's almost impossible now.
Also, after this change, `DataFrame` and `SparkSession` become more consistent with Scala side since pandas is specific to Python, and this change separates pandas-specific APIs away from `DataFrame` or `SparkSession`.
### Does this PR introduce any user-facing change?
No.
### How was this patch tested?
Existing tests should cover. Also, I manually built the PySpark API documentation and checked.
Closes#27109 from HyukjinKwon/pandas-refactoring.
Authored-by: HyukjinKwon <gurwls223@apache.org>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
