Add property to MLWritable.write method, so we can use .write instead of .write()

Add a new test to ml/test.py to check whether the write is a property.
./python/run-tests --python-executables=python2.7 --modules=pyspark-ml

Will test against the following Python executables: ['python2.7']
Will test the following Python modules: ['pyspark-ml']
Finished test(python2.7): pyspark.ml.evaluation (11s)
Finished test(python2.7): pyspark.ml.clustering (16s)
Finished test(python2.7): pyspark.ml.classification (24s)
Finished test(python2.7): pyspark.ml.recommendation (24s)
Finished test(python2.7): pyspark.ml.feature (39s)
Finished test(python2.7): pyspark.ml.regression (26s)
Finished test(python2.7): pyspark.ml.tuning (15s)
Finished test(python2.7): pyspark.ml.tests (30s)
Tests passed in 55 seconds

Author: wm624@hotmail.com <wm624@hotmail.com>

Closes #11945 from wangmiao1981/fix_property.

## What changes were proposed in this pull request?

Added MLReadable and MLWritable to Decision Tree Classifier and Regressor. Added doctests.

## How was this patch tested?

Python Unit tests. Tests added to check persistence in DecisionTreeClassifier and DecisionTreeRegressor.

Author: GayathriMurali <gayathri.m.softie@gmail.com>

Closes #11892 from GayathriMurali/SPARK-13949.

## What changes were proposed in this pull request?

This patch adds type conversion functionality for parameters in Pyspark. A `typeConverter` field is added to the constructor of `Param` class. This argument is a function which converts values passed to this param to the appropriate type if possible. This is beneficial so that the params can fail at set time if they are given inappropriate values, but even more so because coherent error messages are now provided when Py4J cannot cast the python type to the appropriate Java type.

This patch also adds a `TypeConverters` class with factory methods for common type conversions. Most of the changes involve adding these factory type converters to existing params. The previous solution to this issue, `expectedType`, is deprecated and can be removed in 2.1.0 as discussed on the Jira.

## How was this patch tested?

Unit tests were added in python/pyspark/ml/tests.py to test parameter type conversion. These tests check that values that should be convertible are converted correctly, and that the appropriate errors are thrown when invalid values are provided.

Author: sethah <seth.hendrickson16@gmail.com>

Closes #11663 from sethah/SPARK-13068-tc.

Adds support for saving and loading nested ML Pipelines from Python.  Pipeline and PipelineModel do not extend JavaWrapper, but they are able to utilize the JavaMLWriter, JavaMLReader implementations.

Also:
* Separates out interfaces from Java wrapper implementations for MLWritable, MLReadable, MLWriter, MLReader.
* Moves methods _stages_java2py, _stages_py2java into Pipeline, PipelineModel as _transfer_stage_from_java, _transfer_stage_to_java

Added new unit test for nested Pipelines.  Abstracted validity check into a helper method for the 2 unit tests.

Author: Joseph K. Bradley <joseph@databricks.com>

Closes #11866 from jkbradley/nested-pipeline-io.
Closes #11835

## What changes were proposed in this pull request?

Add export/import for all estimators and transformers(which have Scala implementation) under pyspark/ml/classification.py.

## How was this patch tested?

./python/run-tests
./dev/lint-python
Unit tests added to check persistence in Logistic Regression

Author: GayathriMurali <gayathri.m.softie@gmail.com>

Closes #11707 from GayathriMurali/SPARK-13034.

## What changes were proposed in this pull request?

JIRA issue: https://issues.apache.org/jira/browse/SPARK-13038

1. Add load/save to PySpark Pipeline and PipelineModel

2. Add `_transfer_stage_to_java()` and `_transfer_stage_from_java()` for `JavaWrapper`.

## How was this patch tested?

Test with doctest.

Author: Xusen Yin <yinxusen@gmail.com>

Closes #11683 from yinxusen/SPARK-13038-only.

[SPARK-13625][PYSPARK][ML] Added a check to see if an attribute is a property when getting param list

## What changes were proposed in this pull request?

Added a check in pyspark.ml.param.Param.params() to see if an attribute is a property (decorated with `property`) before checking if it is a `Param` instance.  This prevents the property from being invoked to 'get' this attribute, which could possibly cause an error.

## How was this patch tested?

Added a test case with a class has a property that will raise an error when invoked and then call`Param.params` to verify that the property is not invoked, but still able to find another property in the class.  Also ran pyspark-ml test before fix that will trigger an error, and again after the fix to verify that the error was resolved and the method was working properly.

Author: Bryan Cutler <cutlerb@gmail.com>

Closes #11476 from BryanCutler/pyspark-ml-property-attr-SPARK-13625.

## What changes were proposed in this pull request?
The changes proposed were to add train-validation-split to pyspark.ml.tuning.

## How was the this patch tested?
This patch was tested through unit tests located in pyspark/ml/test.py.

This is my original work and I license it to Spark.

Author: JeremyNixon <jnixon2@gmail.com>

Closes #11335 from JeremyNixon/tvs_pyspark.

Pyspark Params class has a method `hasParam(paramName)` which returns `True` if the class has a parameter by that name, but throws an `AttributeError` otherwise. There is not currently a way of getting a Boolean to indicate if a class has a parameter. With Spark 2.0 we could modify the existing behavior of `hasParam` or add an additional method with this functionality.

In Python:
```python
from pyspark.ml.classification import NaiveBayes
nb = NaiveBayes()
print nb.hasParam("smoothing")
print nb.hasParam("notAParam")
```
produces:
> True
> AttributeError: 'NaiveBayes' object has no attribute 'notAParam'

However, in Scala:
```scala
import org.apache.spark.ml.classification.NaiveBayes
val nb  = new NaiveBayes()
nb.hasParam("smoothing")
nb.hasParam("notAParam")
```
produces:
> true
> false

cc holdenk

Author: sethah <seth.hendrickson16@gmail.com>

Closes #10962 from sethah/SPARK-13047.

Test cases should be removed from annotation of ```setXXX``` function, otherwise it will be parts of [Python API docs](https://spark.apache.org/docs/latest/api/python/pyspark.ml.html#pyspark.ml.clustering.KMeans.setInitMode).
cc mengxr jkbradley

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #10975 from yanboliang/clustering-cleanup.

* Implement ```MLWriter/MLWritable/MLReader/MLReadable``` for PySpark.
* Making ```LinearRegression``` to support ```save/load``` as example. After this merged, the work for other transformers/estimators will be easy, then we can list and distribute the tasks to the community.

cc mengxr jkbradley

Author: Yanbo Liang <ybliang8@gmail.com>
Author: Joseph K. Bradley <joseph@databricks.com>

Closes #10469 from yanboliang/spark-11939.

The current python ml params require cut-and-pasting the param setup and description between the class & ```__init__``` methods. Remove this possible case of errors & simplify use of custom params by adding a ```_copy_new_parent``` method to param so as to avoid cut and pasting (and cut and pasting at different indentation levels urgh).

Author: Holden Karau <holden@us.ibm.com>

Closes #10216 from holdenk/SPARK-10509-excessive-param-boiler-plate-code.

This is #9263 from gliptak (improving grouping/display of test case results) with a small fix of bisecting k-means unit test.

Author: Gábor Lipták <gliptak@gmail.com>
Author: Xiangrui Meng <meng@databricks.com>

Closes #10850 from mengxr/SPARK-11295.

This reverts commit c6f971b4.

SPARK-11295 Add packages to JUnit output for Python tests

This improves grouping/display of test case results.

Author: Gábor Lipták <gliptak@gmail.com>

Closes #9263 from gliptak/SPARK-11295.

From JIRA:
Currently, PySpark wrappers for spark.ml Scala classes are brittle when accepting Param types. E.g., Normalizer's "p" param cannot be set to "2" (an integer); it must be set to "2.0" (a float). Fixing this is not trivial since there does not appear to be a natural place to insert the conversion before Python wrappers call Java's Params setter method.

A possible fix will be to include a method "_checkType" to PySpark's Param class which checks the type, prints an error if needed, and converts types when relevant (e.g., int to float, or scipy matrix to array). The Java wrapper method which copies params to Scala can call this method when available.

This fix instead checks the types at set time since I think failing sooner is better, but I can switch it around to check at copy time if that would be better. So far this only converts int to float and other conversions (like scipymatrix to array) are left for the future.

Author: Holden Karau <holden@us.ibm.com>

Closes #9581 from holdenk/SPARK-7675-PySpark-sparkml-Params-type-conversion.

WIP

Author: Gábor Lipták <gliptak@gmail.com>

Closes #8323 from gliptak/SPARK-7021.

Namely "." shows up in some places in the template when using the param docstring and not in others

Author: Holden Karau <holden@pigscanfly.ca>

Closes #9017 from holdenk/SPARK-10767-Make-pyspark-shared-params-codegen-more-consistent.

As ```assertEquals``` is deprecated, so we need to change ```assertEquals``` to ```assertEqual``` for existing python unit tests.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #8814 from yanboliang/spark-10615.

Add a python API for the Stop Words Remover.

Author: Holden Karau <holden@pigscanfly.ca>

Closes #8118 from holdenk/SPARK-9679-python-StopWordsRemover.

* Added isLargerBetter() method to Pyspark Evaluator to match the Scala version.
* JavaEvaluator delegates isLargerBetter() to underlying Scala object.
* Added check for isLargerBetter() in CrossValidator to determine whether to use argmin or argmax.
* Added test cases for where smaller is better (RMSE) and larger is better (R-Squared).

(This contribution is my original work and that I license the work to the project under Sparks' open source license)

Author: noelsmith <mail@noelsmith.com>

Closes #8399 from noel-smith/pyspark-rmse-xval-fix.

Python API for N-gram feature transformer

Author: Feynman Liang <fliang@databricks.com>

Closes #6960 from feynmanliang/ngram-featurizer-python and squashes the following commits:

f9e37c9 [Feynman Liang] Remove debugging code
4dd81f4 [Feynman Liang] Fix typo and doctest
06c79ac [Feynman Liang] Style guide
26c1175 [Feynman Liang] Add python NGram API

[SPARK-7511] [MLLIB] pyspark ml seed param should be random by default or 42 is quite funny but not very random

Author: Holden Karau <holden@pigscanfly.ca>

Closes #6139 from holdenk/SPARK-7511-pyspark-ml-seed-param-should-be-random-by-default-or-42-is-quite-funny-but-not-very-random and squashes the following commits:

591f8e5 [Holden Karau] specify old seed for doc tests
2470004 [Holden Karau] Fix a bunch of seeds with default values to have None as the default which will then result in using the hash of the class name
cbad96d [Holden Karau] Add the setParams function that is used in the real code
423b8d7 [Holden Karau] Switch the test code to behave slightly more like production code. also don't check the param map value only check for key existence
140d25d [Holden Karau] remove extra space
926165a [Holden Karau] Add some missing newlines for pep8 style
8616751 [Holden Karau] merge in master
58532e6 [Holden Karau] its the __name__ method, also treat None values as not set
56ef24a [Holden Karau] fix test and regenerate base
afdaa5c [Holden Karau] make sure different classes have different results
68eb528 [Holden Karau] switch default seed to hash of type of self
89c4611 [Holden Karau] Merge branch 'master' into SPARK-7511-pyspark-ml-seed-param-should-be-random-by-default-or-42-is-quite-funny-but-not-very-random
31cd96f [Holden Karau] specify the seed to randomforestregressor test
e1b947f [Holden Karau] Style fixes
ce90ec8 [Holden Karau] merge in master
bcdf3c9 [Holden Karau] update docstring seeds to none and some other default seeds from 42
65eba21 [Holden Karau] pep8 fixes
0e3797e [Holden Karau] Make seed default to random in more places
213a543 [Holden Karau] Simplify the generated code to only include set default if there is a default rather than having None is note None in the generated code
1ff17c2 [Holden Karau] Make the seed random for HasSeed in python

This PR makes pipeline stages in Python copyable and hence simplifies some implementations. It also includes the following changes:

1. Rename `paramMap` and `defaultParamMap` to `_paramMap` and `_defaultParamMap`, respectively.
2. Accept a list of param maps in `fit`.
3. Use parent uid and name to identify param.

jkbradley

Author: Xiangrui Meng <meng@databricks.com>
Author: Joseph K. Bradley <joseph@databricks.com>

Closes #6088 from mengxr/SPARK-7380 and squashes the following commits:

413c463 [Xiangrui Meng] remove unnecessary doc
4159f35 [Xiangrui Meng] Merge remote-tracking branch 'apache/master' into SPARK-7380
611c719 [Xiangrui Meng] fix python style
68862b8 [Xiangrui Meng] update _java_obj initialization
927ad19 [Xiangrui Meng] fix ml/tests.py
0138fc3 [Xiangrui Meng] update feature transformers and fix a bug in RegexTokenizer
9ca44fb [Xiangrui Meng] simplify Java wrappers and add tests
c7d84ef [Xiangrui Meng] update ml/tests.py to test copy params
7e0d27f [Xiangrui Meng] merge master
46840fb [Xiangrui Meng] update wrappers
b6db1ed [Xiangrui Meng] update all self.paramMap to self._paramMap
46cb6ed [Xiangrui Meng] merge master
a163413 [Xiangrui Meng] fix style
1042e80 [Xiangrui Meng] Merge remote-tracking branch 'apache/master' into SPARK-7380
9630eae [Xiangrui Meng] fix Identifiable._randomUID
13bd70a [Xiangrui Meng] update ml/tests.py
64a536c [Xiangrui Meng] use _fit/_transform/_evaluate to simplify the impl
02abf13 [Xiangrui Meng] Merge remote-tracking branch 'apache/master' into copyable-python
66ce18c [Joseph K. Bradley] some cleanups before sending to Xiangrui
7431272 [Joseph K. Bradley] Rebased with master

Modified 2 files:
python/pyspark/ml/param/_shared_params_code_gen.py
python/pyspark/ml/param/shared.py

Generated shared.py on Linux using Python 2.6.6 on Redhat Enterprise Linux Server 6.6.
python _shared_params_code_gen.py > shared.py

Only changed maxIter, regParam, rawPredictionCol based on strings from SharedParamsCodeGen.scala.  Note warning was displayed when committing shared.py:
warning: LF will be replaced by CRLF in python/pyspark/ml/param/shared.py.

Author: Glenn Weidner <gweidner@us.ibm.com>

Closes #6023 from gweidner/br-7427 and squashes the following commits:

db72e32 [Glenn Weidner] [SPARK-7427] [PySpark] Make sharedParams match in Scala, Python
825e4a9 [Glenn Weidner] [SPARK-7427] [PySpark] Make sharedParams match in Scala, Python
e6a865e [Glenn Weidner] [SPARK-7427] [PySpark] Make sharedParams match in Scala, Python
1eee702 [Glenn Weidner] Merge remote-tracking branch 'upstream/master'
1ac10e5 [Glenn Weidner] Merge remote-tracking branch 'upstream/master'
cafd104 [Glenn Weidner] Merge remote-tracking branch 'upstream/master'
9bea1eb [Glenn Weidner] Merge remote-tracking branch 'upstream/master'
4a35c20 [Glenn Weidner] Merge remote-tracking branch 'upstream/master'
9790cbe [Glenn Weidner] Merge remote-tracking branch 'upstream/master'
d9c30f4 [Glenn Weidner] [SPARK-7275] [SQL] [WIP] Make LogicalRelation public

Fixes bug with PySpark cvModel not having UID
Also made small PySpark fixes: Evaluator should inherit from Params.  MockModel should inherit from Model.

CC: mengxr

Author: Joseph K. Bradley <joseph@databricks.com>

Closes #5968 from jkbradley/pyspark-cv-uid and squashes the following commits:

57f13cd [Joseph K. Bradley] Made CrossValidatorModel call parent init in PySpark

Same as #5431 but for Python. jkbradley

Author: Xiangrui Meng <meng@databricks.com>

Closes #5534 from mengxr/SPARK-6893 and squashes the following commits:

d3b519b [Xiangrui Meng] address comments
ebaccc6 [Xiangrui Meng] style update
fce244e [Xiangrui Meng] update explainParams with test
4d6b07a [Xiangrui Meng] add tests
5294500 [Xiangrui Meng] update default param handling in python

This PR adds Python API for ML pipeline and parameters. The design doc can be found on the JIRA page. It includes transformers and an estimator to demo the simple text classification example code.

TODO:
- [x] handle parameters in LRModel
- [x] unit tests
- [x] missing some docs

CC: davies jkbradley

Author: Xiangrui Meng <meng@databricks.com>
Author: Davies Liu <davies@databricks.com>

Closes #4151 from mengxr/SPARK-4586 and squashes the following commits:

415268e [Xiangrui Meng] remove inherit_doc from __init__
edbd6fe [Xiangrui Meng] move Identifiable to ml.util
44c2405 [Xiangrui Meng] Merge pull request #2 from davies/ml
dd1256b [Xiangrui Meng] Merge remote-tracking branch 'apache/master' into SPARK-4586
14ae7e2 [Davies Liu] fix docs
54ca7df [Davies Liu] fix tests
78638df [Davies Liu] Merge branch 'SPARK-4586' of github.com:mengxr/spark into ml
fc59a02 [Xiangrui Meng] Merge remote-tracking branch 'apache/master' into SPARK-4586
1dca16a [Davies Liu] refactor
090b3a3 [Davies Liu] Merge branch 'master' of github.com:apache/spark into ml
0882513 [Xiangrui Meng] update doc style
a4f4dbf [Xiangrui Meng] add unit test for LR
7521d1c [Xiangrui Meng] add unit tests to HashingTF and Tokenizer
ba0ba1e [Xiangrui Meng] add unit tests for pipeline
0586c7b [Xiangrui Meng] add more comments to the example
5153cff [Xiangrui Meng] simplify java models
036ca04 [Xiangrui Meng] gen numFeatures
46fa147 [Xiangrui Meng] update mllib/pom.xml to include python files in the assembly
1dcc17e [Xiangrui Meng] update code gen and make param appear in the doc
f66ba0c [Xiangrui Meng] make params a property
d5efd34 [Xiangrui Meng] update doc conf and move embedded param map to instance attribute
f4d0fe6 [Xiangrui Meng] use LabeledDocument and Document in example
05e3e40 [Xiangrui Meng] update example
d3e8dbe [Xiangrui Meng] more docs optimize pipeline.fit impl
56de571 [Xiangrui Meng] fix style
d0c5bb8 [Xiangrui Meng] a working copy
bce72f4 [Xiangrui Meng] Merge remote-tracking branch 'apache/master' into SPARK-4586
17ecfb9 [Xiangrui Meng] code gen for shared params
d9ea77c [Xiangrui Meng] update doc
c18dca1 [Xiangrui Meng] make the example working
dadd84e [Xiangrui Meng] add base classes and docs
a3015cf [Xiangrui Meng] add Estimator and Transformer
46eea43 [Xiangrui Meng] a pipeline in python
33b68e0 [Xiangrui Meng] a working LR