### What changes were proposed in this pull request?
This PR proposes to reorder the items in User Guide in PySpark documentation in order to place general guides first and advance ones later.
### Why are the changes needed?
For users to more easily follow.
### Does this PR introduce _any_ user-facing change?
Yes, it changes the order in the items in documentation .
### How was this patch tested?
Manually verified the documentation after building:
<img width="768" alt="Screen Shot 2021-03-22 at 2 38 41 PM" src="https://user-images.githubusercontent.com/6477701/111945072-5537d680-8b1c-11eb-9f43-02f3ad63a509.png">
FWIW, the current page: https://spark.apache.org/docs/latest/api/python/user_guide/index.htmlCloses#31922 from HyukjinKwon/SPARK-34818.
Authored-by: HyukjinKwon <gurwls223@apache.org>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
### What changes were proposed in this pull request?
This PR proposes:
- Change http to https for better security
- Change http://apache-spark-developers-list.1001551.n3.nabble.com/ to official mailing list link (https://mail-archives.apache.org/mod_mbox/spark-dev/)
### Why are the changes needed?
For better security, and to use official link.
### Does this PR introduce _any_ user-facing change?
Yes, It exposes more secure and correct links to the PySpark end users in PySpark documentation.
### How was this patch tested?
I manually checked if each link works
Closes#31616 from HyukjinKwon/minor-https.
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:
- Add a link of quick start in PySpark docs into "Programming Guides" in Spark main docs
- `ML` / `MLlib` -> `MLlib (DataFrame-based)` / `MLlib (RDD-based)` in API reference page
- Mention other user guides as well because the guide such as [ML](http://spark.apache.org/docs/latest/ml-guide.html) and [SQL](http://spark.apache.org/docs/latest/sql-programming-guide.html).
- Mention other migration guides as well because PySpark can get affected by it.
### Why are the changes needed?
For better documentation.
### Does this PR introduce _any_ user-facing change?
It fixes user-facing docs. However, it's not released out yet.
### How was this patch tested?
Manually tested by running:
```bash
cd docs
SKIP_SCALADOC=1 SKIP_RDOC=1 SKIP_SQLDOC=1 jekyll serve --watch
```
Closes#31082 from HyukjinKwon/SPARK-34041.
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 document PySpark specific packaging guidelines.
### Why are the changes needed?
To have a single place for PySpark users, and better documentation.
### Does this PR introduce _any_ user-facing change?
Yes
### How was this patch tested?
```
cd python/docs
make clean html
```
Closes#29806 from fhoering/add_doc_python_packaging.
Lead-authored-by: Fabian Höring <f.horing@criteo.com>
Co-authored-by: Hyukjin Kwon <gurwls223@gmail.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
### What changes were proposed in this pull request?
This PR proposes to move Arrow usage guide from Spark documentation site to PySpark documentation site (at "User Guide").
Here is the demo for reviewing quicker: https://hyukjin-spark.readthedocs.io/en/stable/user_guide/arrow_pandas.html
### Why are the changes needed?
To have a single place for PySpark users, and better documentation.
### Does this PR introduce _any_ user-facing change?
Yes, it will move https://spark.apache.org/docs/latest/sql-pyspark-pandas-with-arrow.html to our PySpark documentation.
### How was this patch tested?
```bash
cd docs
SKIP_SCALADOC=1 SKIP_RDOC=1 SKIP_SQLDOC=1 jekyll serve --watch
```
and
```bash
cd python/docs
make clean html
```
Closes#29548 from HyukjinKwon/SPARK-32183.
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 redesign the PySpark documentation.
I made a demo site to make it easier to review: https://hyukjin-spark.readthedocs.io/en/stable/reference/index.html.
Here is the initial draft for the final PySpark docs shape: https://hyukjin-spark.readthedocs.io/en/latest/index.html.
In more details, this PR proposes:
1. Use [pydata_sphinx_theme](https://github.com/pandas-dev/pydata-sphinx-theme) theme - [pandas](https://pandas.pydata.org/docs/) and [Koalas](https://koalas.readthedocs.io/en/latest/) use this theme. The CSS overwrite is ported from Koalas. The colours in the CSS were actually chosen by designers to use in Spark.
2. Use the Sphinx option to separate `source` and `build` directories as the documentation pages will likely grow.
3. Port current API documentation into the new style. It mimics Koalas and pandas to use the theme most effectively.
One disadvantage of this approach is that you should list up APIs or classes; however, I think this isn't a big issue in PySpark since we're being conservative on adding APIs. I also intentionally listed classes only instead of functions in ML and MLlib to make it relatively easier to manage.
### Why are the changes needed?
Often I hear the complaints, from the users, that current PySpark documentation is pretty messy to read - https://spark.apache.org/docs/latest/api/python/index.html compared other projects such as [pandas](https://pandas.pydata.org/docs/) and [Koalas](https://koalas.readthedocs.io/en/latest/).
It would be nicer if we can make it more organised instead of just listing all classes, methods and attributes to make it easier to navigate.
Also, the documentation has been there from almost the very first version of PySpark. Maybe it's time to update it.
### Does this PR introduce _any_ user-facing change?
Yes, PySpark API documentation will be redesigned.
### How was this patch tested?
Manually tested, and the demo site was made to show.
Closes#29188 from HyukjinKwon/SPARK-32179.
Authored-by: HyukjinKwon <gurwls223@apache.org>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
