spark-instrumented-optimizer/python/docs/pyspark.sql.rst
HyukjinKwon ee8d661058 [SPARK-30434][PYTHON][SQL] Move pandas related functionalities into 'pandas' sub-package
### 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>
2020-01-09 10:22:50 +09:00

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pyspark.sql module
==================
Module Context
--------------
.. automodule:: pyspark.sql
:members:
:undoc-members:
:inherited-members:
:exclude-members: builder
.. We need `exclude-members` to prevent default description generations
as a workaround for old Sphinx (< 1.6.6).
pyspark.sql.types module
------------------------
.. automodule:: pyspark.sql.types
:members:
:undoc-members:
pyspark.sql.functions module
----------------------------
.. automodule:: pyspark.sql.functions
:members:
:undoc-members:
pyspark.sql.avro.functions module
---------------------------------
.. automodule:: pyspark.sql.avro.functions
:members:
:undoc-members:
pyspark.sql.streaming module
----------------------------
.. automodule:: pyspark.sql.streaming
:members:
:undoc-members: