[SPARK-19319][BACKPORT-2.1][SPARKR] SparkR Kmeans summary returns error when the cluster size doesn't equal to k

## What changes were proposed in this pull request?

Backport fix of #16666

## How was this patch tested?

Backport unit tests

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

Closes #16761 from wangmiao1981/kmeansport.

[SPARK-16473][MLLIB] Fix BisectingKMeans Algorithm failing in edge case where no children exist in updateAssignments

## What changes were proposed in this pull request?

Fix a bug in which BisectingKMeans fails with error:
java.util.NoSuchElementException: key not found: 166
        at scala.collection.MapLike$class.default(MapLike.scala:228)
        at scala.collection.AbstractMap.default(Map.scala:58)
        at scala.collection.MapLike$class.apply(MapLike.scala:141)
        at scala.collection.AbstractMap.apply(Map.scala:58)
        at org.apache.spark.mllib.clustering.BisectingKMeans$$anonfun$org$apache$spark$mllib$clustering$BisectingKMeans$$updateAssignments$1$$anonfun$2.apply$mcDJ$sp(BisectingKMeans.scala:338)
        at org.apache.spark.mllib.clustering.BisectingKMeans$$anonfun$org$apache$spark$mllib$clustering$BisectingKMeans$$updateAssignments$1$$anonfun$2.apply(BisectingKMeans.scala:337)
        at org.apache.spark.mllib.clustering.BisectingKMeans$$anonfun$org$apache$spark$mllib$clustering$BisectingKMeans$$updateAssignments$1$$anonfun$2.apply(BisectingKMeans.scala:337)
        at scala.collection.TraversableOnce$$anonfun$minBy$1.apply(TraversableOnce.scala:231)
        at scala.collection.LinearSeqOptimized$class.foldLeft(LinearSeqOptimized.scala:111)
        at scala.collection.immutable.List.foldLeft(List.scala:84)
        at scala.collection.LinearSeqOptimized$class.reduceLeft(LinearSeqOptimized.scala:125)
        at scala.collection.immutable.List.reduceLeft(List.scala:84)
        at scala.collection.TraversableOnce$class.minBy(TraversableOnce.scala:231)
        at scala.collection.AbstractTraversable.minBy(Traversable.scala:105)
        at org.apache.spark.mllib.clustering.BisectingKMeans$$anonfun$org$apache$spark$mllib$clustering$BisectingKMeans$$updateAssignments$1.apply(BisectingKMeans.scala:337)
        at org.apache.spark.mllib.clustering.BisectingKMeans$$anonfun$org$apache$spark$mllib$clustering$BisectingKMeans$$updateAssignments$1.apply(BisectingKMeans.scala:334)
        at scala.collection.Iterator$$anon$11.next(Iterator.scala:328)
        at scala.collection.Iterator$$anon$14.hasNext(Iterator.scala:389)

## How was this patch tested?

The dataset was run against the code change to verify that the code works.  I will try to add unit tests to the code.

(Please explain how this patch was tested. E.g. unit tests, integration tests, manual tests)
(If this patch involves UI changes, please attach a screenshot; otherwise, remove this)

Please review http://spark.apache.org/contributing.html before opening a pull request.

Author: Ilya Matiach <ilmat@microsoft.com>

Closes #16355 from imatiach-msft/ilmat/fix-kmeans.

## What changes were proposed in this pull request?
This is a supplement to PR #16516 which did not make the value from `getFamily` case insensitive. Current tests of poisson/binomial glm with weight fail when specifying 'Poisson' or 'Binomial', because the calculation of `dispersion` and `pValue` checks the value of family retrieved from `getFamily`
```
model.getFamily == Binomial.name || model.getFamily == Poisson.name
```

## How was this patch tested?
Update existing tests for 'Poisson' and 'Binomial'.

yanboliang felixcheung imatiach-msft

Author: actuaryzhang <actuaryzhang10@gmail.com>

Closes #16675 from actuaryzhang/family.

(cherry picked from commit f067acef)
Signed-off-by: Yanbo Liang <ybliang8@gmail.com>

## What changes were proposed in this pull request?
MLlib ```GeneralizedLinearRegression``` ```family``` and ```link``` should be case insensitive. This is consistent with some other MLlib params such as [```featureSubsetStrategy```](https://github.com/apache/spark/blob/master/mllib/src/main/scala/org/apache/spark/ml/tree/treeParams.scala#L415

).

## How was this patch tested?
Update corresponding tests.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #16516 from yanboliang/spark-19133.

(cherry picked from commit 3dcad9fa)
Signed-off-by: Yanbo Liang <ybliang8@gmail.com>

## What changes were proposed in this pull request?
Back port the fix to SPARK-19066 to 2.1 branch.

## How was this patch tested?
Unit tests

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

Closes #16623 from wangmiao1981/bugport.

[SPARK-19110][ML][MLLIB] DistributedLDAModel returns different logPrior for original and loaded model

## What changes were proposed in this pull request?

While adding DistributedLDAModel training summary for SparkR, I found that the logPrior for original and loaded model is different.
For example, in the test("read/write DistributedLDAModel"), I add the test:
val logPrior = model.asInstanceOf[DistributedLDAModel].logPrior
val logPrior2 = model2.asInstanceOf[DistributedLDAModel].logPrior
assert(logPrior === logPrior2)
The test fails:
-4.394180878889078 did not equal -4.294290536919573

The reason is that `graph.vertices.aggregate(0.0)(seqOp, _ + _)` only returns the value of a single vertex instead of the aggregation of all vertices. Therefore, when the loaded model does the aggregation in a different order, it returns different `logPrior`.

Please refer to #16464 for details.
## How was this patch tested?
Add a new unit test for testing logPrior.

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

Closes #16491 from wangmiao1981/ldabug.

(cherry picked from commit 036b5034)
Signed-off-by: Joseph K. Bradley <joseph@databricks.com>

Remove spark-tag's compile-scope dependency (and, indirectly, spark-core's compile-scope transitive-dependency) on scalatest by splitting test-oriented tags into spark-tags' test JAR.

Alternative to #16303.

Author: Ryan Williams <ryan.blake.williams@gmail.com>

Closes #16311 from ryan-williams/tt.

(cherry picked from commit afd9bc1d)
Signed-off-by: Marcelo Vanzin <vanzin@cloudera.com>

## What changes were proposed in this pull request?

Updated Scala param and Python param to have quotes around the options making it easier for users to read.

## How was this patch tested?

Manually checked the docstrings

Author: krishnakalyan3 <krishnakalyan3@gmail.com>

Closes #16242 from krishnakalyan3/doc-string.

(cherry picked from commit c802ad87)
Signed-off-by: Sean Owen <sowen@cloudera.com>

## What changes were proposed in this pull request?

The API documentation build was failing when using Java 8 due to incorrect character `>` in Javadoc.

Replace `>` with literals in Javadoc to allow the build to pass.

## How was this patch tested?

Documentation was built and inspected manually to ensure it still displays correctly in the browser

```
cd docs && jekyll serve
```

Author: Michal Senkyr <mike.senkyr@gmail.com>

Closes #16201 from michalsenkyr/javadoc8-gt-fix.

(cherry picked from commit 11432483)
Signed-off-by: Sean Owen <sowen@cloudera.com>

## What changes were proposed in this pull request?
Reviewing SparkR ML wrappers API for 2.1 release, mainly two issues:
* Remove ```probabilityCol``` from the argument list of ```spark.logit``` and ```spark.randomForest```. Since it was used when making prediction and should be an argument of ```predict```, and we will work on this at [SPARK-18618](https://issues.apache.org/jira/browse/SPARK-18618

) in the next release cycle.
* Fix ```spark.als``` params to make it consistent with MLlib.

## How was this patch tested?
Existing tests.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #16169 from yanboliang/spark-18326.

(cherry picked from commit 97255497)
Signed-off-by: Yanbo Liang <ybliang8@gmail.com>

Poisson GLM fails for many standard data sets (see example in test or JIRA). The issue is incorrect initialization leading to almost zero probability and weights. Specifically, the mean is initialized as the response, which could be zero. Applying the log link results in very negative numbers (protected against -Inf), which again leads to close to zero probability and weights in the weighted least squares. Fix and test are included in the commits.

## What changes were proposed in this pull request?
Update initialization in Poisson GLM

## How was this patch tested?
Add test in GeneralizedLinearRegressionSuite

srowen sethah yanboliang HyukjinKwon mengxr

Author: actuaryzhang <actuaryzhang10@gmail.com>

Closes #16131 from actuaryzhang/master.

(cherry picked from commit b8280271)
Signed-off-by: Sean Owen <sowen@cloudera.com>

## What changes were proposed in this pull request?
Several cleanup and improvements for ```spark.logit```:
* ```summary``` should return coefficients matrix, and should output labels for each class if the model is multinomial logistic regression model.
* ```summary``` should not return ```areaUnderROC, roc, pr, ...```, since most of them are DataFrame which are less important for R users. Meanwhile, these metrics ignore instance weights (setting all to 1.0) which will be changed in later Spark version. In case it will introduce breaking changes, we do not expose them currently.
* SparkR test improvement: comparing the training result with native R glmnet.
* Remove argument ```aggregationDepth``` from ```spark.logit```, since it's an expert Param(related with Spark architecture and job execution) that would be used rarely by R users.

## How was this patch tested?
Unit tests.

The ```summary``` output after this change:
multinomial logistic regression:
```
> df <- suppressWarnings(createDataFrame(iris))
> model <- spark.logit(df, Species ~ ., regParam = 0.5)
> summary(model)
$coefficients
             versicolor  virginica   setosa
(Intercept)  1.514031    -2.609108   1.095077
Sepal_Length 0.02511006  0.2649821   -0.2900921
Sepal_Width  -0.5291215  -0.02016446 0.549286
Petal_Length 0.03647411  0.1544119   -0.190886
Petal_Width  0.000236092 0.4195804   -0.4198165
```
binomial logistic regression:
```
> df <- suppressWarnings(createDataFrame(iris))
> training <- df[df$Species %in% c("versicolor", "virginica"), ]
> model <- spark.logit(training, Species ~ ., regParam = 0.5)
> summary(model)
$coefficients
             Estimate
(Intercept)  -6.053815
Sepal_Length 0.2449379
Sepal_Width  0.1648321
Petal_Length 0.4730718
Petal_Width  1.031947
```

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #16117 from yanboliang/spark-18686.

(cherry picked from commit 90b59d1b)
Signed-off-by: Yanbo Liang <ybliang8@gmail.com>

## What changes were proposed in this pull request?
add `setFeaturesCol` and `setPredictionCol` for `OneVsRestModel`

## How was this patch tested?
added tests

Author: Zheng RuiFeng <ruifengz@foxmail.com>

Closes #16059 from zhengruifeng/ovrm_setCol.

(cherry picked from commit bdfe7f67)
Signed-off-by: Yanbo Liang <ybliang8@gmail.com>

[SPARK-18291][SPARKR][ML] Revert "[SPARK-18291][SPARKR][ML] SparkR glm predict should output original label when family = binomial."

## What changes were proposed in this pull request?
It's better we can fix this issue by providing an option ```type``` for users to change the ```predict``` output schema, then they could output probabilities, log-space predictions, or original labels. In order to not involve breaking API change for 2.1, so revert this change firstly and will add it back after [SPARK-18618](https://issues.apache.org/jira/browse/SPARK-18618

) resolved.

## How was this patch tested?
Existing unit tests.

This reverts commit daa975f4.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #16118 from yanboliang/spark-18291-revert.

(cherry picked from commit a985dd8e)
Signed-off-by: Joseph K. Bradley <joseph@databricks.com>

## What changes were proposed in this pull request?

Similar to SPARK-18401, as a classification algorithm, logistic regression should support output original label instead of supporting index label.

In this PR, original label output is supported and test cases are modified and added. Document is also modified.

## How was this patch tested?

Unit tests.

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

Closes #15910 from wangmiao1981/audit.

(cherry picked from commit 2eb6764f)
Signed-off-by: Yanbo Liang <ybliang8@gmail.com>

## What changes were proposed in this pull request?
API review for 2.1, except ```LSH``` related classes which are still under development.

## How was this patch tested?
Only doc changes, no new tests.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #16009 from yanboliang/spark-18318.

(cherry picked from commit 60022bfd)
Signed-off-by: Joseph K. Bradley <joseph@databricks.com>

## What changes were proposed in this pull request?

Fix a broadcasted variable leak occurring at each invocation of CostFun in L-BFGS.

## How was this patch tested?

UTests + check that fixed fatal memory consumption on Criteo's use cases.

This contribution is made on behalf of Criteo S.A.
(http://labs.criteo.com/

) under the terms of the Apache v2 License.

Author: Anthony Truchet <a.truchet@criteo.com>

Closes #16040 from AnthonyTruchet/SPARK-18612-lbfgs-cost-fun.

(cherry picked from commit c5a64d76)
Signed-off-by: Sean Owen <sowen@cloudera.com>

## What changes were proposed in this pull request?
make a pass through the items marked as Experimental or DeveloperApi and see if any are stable enough to be unmarked. Also check for items marked final or sealed to see if they are stable enough to be opened up as APIs.

Some discussions in the jira: https://issues.apache.org/jira/browse/SPARK-18319



## How was this patch tested?
existing ut

Author: Yuhao <yuhao.yang@intel.com>
Author: Yuhao Yang <hhbyyh@gmail.com>

Closes #15972 from hhbyyh/experimental21.

(cherry picked from commit 9b670bca)
Signed-off-by: Joseph K. Bradley <joseph@databricks.com>

## What changes were proposed in this pull request?
Mainly two changes:
* Move DT/RF/GBT Param setter methods to subclasses.
* Deprecate corresponding setter methods in the model classes.

See discussion here https://github.com/apache/spark/pull/15913#discussion_r89662469

.

## How was this patch tested?
Existing tests.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #16017 from yanboliang/spark-18592.

(cherry picked from commit 95f79850)
Signed-off-by: Joseph K. Bradley <joseph@databricks.com>

## What changes were proposed in this pull request?

Currently, single line comment does not mark down backticks to `<code>..</code>` but prints as they are (`` `..` ``). For example, the line below:

```scala
/** Return an RDD with the pairs from `this` whose keys are not in `other`. */
```

So, we could work around this as below:

```scala
/**
 * Return an RDD with the pairs from `this` whose keys are not in `other`.
 */
```

- javadoc

  - **Before**
    ![2016-11-29 10 39 14](https://cloud.githubusercontent.com/assets/6477701/20693606/e64c8f90-b622-11e6-8dfc-4a029216e23d.png)

  - **After**
    ![2016-11-29 10 39 08](https://cloud.githubusercontent.com/assets/6477701/20693607/e7280d36-b622-11e6-8502-d2e21cd5556b.png)

- scaladoc (this one looks fine either way)

  - **Before**
    ![2016-11-29 10 38 22](https://cloud.githubusercontent.com/assets/6477701/20693640/12c18aa8-b623-11e6-901a-693e2f6f8066.png)

  - **After**
    ![2016-11-29 10 40 05](https://cloud.githubusercontent.com/assets/6477701/20693642/14eb043a-b623-11e6-82ac-7cd0000106d1.png

)

I suspect this is related with SPARK-16153 and genjavadoc issue in ` typesafehub/genjavadoc#85`.

## How was this patch tested?

I found them via

```
grep -r "\/\*\*.*\`" . | grep .scala
````

and then checked if each is in the public API documentation with manually built docs (`jekyll build`) with Java 7.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #16050 from HyukjinKwon/javadoc-markdown.

(cherry picked from commit 1a870090)
Signed-off-by: Sean Owen <sowen@cloudera.com>

[SPARK-3359][DOCS] Make javadoc8 working for unidoc/genjavadoc compatibility in Java API documentation

## What changes were proposed in this pull request?

This PR make `sbt unidoc` complete with Java 8.

This PR roughly includes several fixes as below:

- Fix unrecognisable class and method links in javadoc by changing it from `[[..]]` to `` `...` ``

  ```diff
  - * A column that will be computed based on the data in a [[DataFrame]].
  + * A column that will be computed based on the data in a `DataFrame`.
  ```

- Fix throws annotations so that they are recognisable in javadoc

- Fix URL links to `<a href="http..."></a>`.

  ```diff
  - * [[http://en.wikipedia.org/wiki/Decision_tree_learning Decision tree]] model for regression.
  + * <a href="http://en.wikipedia.org/wiki/Decision_tree_learning">
  + * Decision tree (Wikipedia)</a> model for regression.
  ```

  ```diff
  -   * see http://en.wikipedia.org/wiki/Receiver_operating_characteristic
  +   * see <a href="http://en.wikipedia.org/wiki/Receiver_operating_characteristic">
  +   * Receiver operating characteristic (Wikipedia)</a>
  ```

- Fix < to > to

  - `greater than`/`greater than or equal to` or `less than`/`less than or equal to` where applicable.

  - Wrap it with `{{{...}}}` to print them in javadoc or use `{code ...}` or `{literal ..}`. Please refer https://github.com/apache/spark/pull/16013#discussion_r89665558



- Fix `</p>` complaint

## How was this patch tested?

Manually tested by `jekyll build` with Java 7 and 8

```
java version "1.7.0_80"
Java(TM) SE Runtime Environment (build 1.7.0_80-b15)
Java HotSpot(TM) 64-Bit Server VM (build 24.80-b11, mixed mode)
```

```
java version "1.8.0_45"
Java(TM) SE Runtime Environment (build 1.8.0_45-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.45-b02, mixed mode)
```

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #16013 from HyukjinKwon/SPARK-3359-errors-more.

(cherry picked from commit f830bb91)
Signed-off-by: Sean Owen <sowen@cloudera.com>

## What changes were proposed in this pull request?

(1) Change output schema to `Array of Vector` instead of `Vectors`
(2) Use `numHashTables` as the dimension of Array
(3) Rename `RandomProjection` to `BucketedRandomProjectionLSH`, `MinHash` to `MinHashLSH`
(4) Make `randUnitVectors/randCoefficients` private
(5) Make Multi-Probe NN Search and `hashDistance` private for future discussion

Saved for future PRs:
(1) AND-amplification and `numHashFunctions` as the dimension of Vector are saved for a future PR.
(2) `hashDistance` and MultiProbe NN Search needs more discussion. The current implementation is just a backward compatible one.

## How was this patch tested?
Related unit tests are modified to make sure the performance of LSH are ensured, and the outputs of the APIs meets expectation.

Author: Yun Ni <yunn@uber.com>
Author: Yunni <Euler57721@gmail.com>

Closes #15874 from Yunni/SPARK-18408-yunn-api-improvements.

(cherry picked from commit 05f7c6ff)
Signed-off-by: Joseph K. Bradley <joseph@databricks.com>

## What changes were proposed in this pull request?
Remove deprecated methods for ML.

## How was this patch tested?
Existing tests.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #15913 from yanboliang/spark-18481.

(cherry picked from commit c4a7eef0)
Signed-off-by: Yanbo Liang <ybliang8@gmail.com>

[SPARK-3359][BUILD][DOCS] More changes to resolve javadoc 8 errors that will help unidoc/genjavadoc compatibility

## What changes were proposed in this pull request?

This PR only tries to fix things that looks pretty straightforward and were fixed in other previous PRs before.

This PR roughly fixes several things as below:

- Fix unrecognisable class and method links in javadoc by changing it from `[[..]]` to `` `...` ``

  ```
  [error] .../spark/sql/core/target/java/org/apache/spark/sql/streaming/DataStreamReader.java:226: error: reference not found
  [error]    * Loads text files and returns a {link DataFrame} whose schema starts with a string column named
  ```

- Fix an exception annotation and remove code backticks in `throws` annotation

  Currently, sbt unidoc with Java 8 complains as below:

  ```
  [error] .../java/org/apache/spark/sql/streaming/StreamingQuery.java:72: error: unexpected text
  [error]    * throws StreamingQueryException, if <code>this</code> query has terminated with an exception.
  ```

  `throws` should specify the correct class name from `StreamingQueryException,` to `StreamingQueryException` without backticks. (see [JDK-8007644](https://bugs.openjdk.java.net/browse/JDK-8007644)).

- Fix `[[http..]]` to `<a href="http..."></a>`.

  ```diff
  -   * [[https://blogs.oracle.com/java-platform-group/entry/diagnosing_tls_ssl_and_https Oracle
  -   * blog page]].
  +   * <a href="https://blogs.oracle.com/java-platform-group/entry/diagnosing_tls_ssl_and_https

">
  +   * Oracle blog page</a>.
  ```

   `[[http...]]` link markdown in scaladoc is unrecognisable in javadoc.

- It seems class can't have `return` annotation. So, two cases of this were removed.

  ```
  [error] .../java/org/apache/spark/mllib/regression/IsotonicRegression.java:27: error: invalid use of return
  [error]    * return New instance of IsotonicRegression.
  ```

- Fix < to `&lt;` and > to `&gt;` according to HTML rules.

- Fix `</p>` complaint

- Exclude unrecognisable in javadoc, `constructor`, `todo` and `groupname`.

## How was this patch tested?

Manually tested by `jekyll build` with Java 7 and 8

```
java version "1.7.0_80"
Java(TM) SE Runtime Environment (build 1.7.0_80-b15)
Java HotSpot(TM) 64-Bit Server VM (build 24.80-b11, mixed mode)
```

```
java version "1.8.0_45"
Java(TM) SE Runtime Environment (build 1.8.0_45-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.45-b02, mixed mode)
```

Note: this does not yet make sbt unidoc suceed with Java 8 yet but it reduces the number of errors with Java 8.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #15999 from HyukjinKwon/SPARK-3359-errors.

(cherry picked from commit 51b1c155)
Signed-off-by: Sean Owen <sowen@cloudera.com>

## What changes were proposed in this pull request?
add `setFeaturesCol` and `setPredictionCol` for BiKModel and GMModel
add `setProbabilityCol` for GMModel
## How was this patch tested?
existing tests

Author: Zheng RuiFeng <ruifengz@foxmail.com>

Closes #15957 from zhengruifeng/bikm_set.

(cherry picked from commit 2dfabec3)
Signed-off-by: Yanbo Liang <ybliang8@gmail.com>

## What changes were proposed in this pull request?
* Fix SparkR ```spark.glm``` errors when fitting on collinear data, since ```standard error of coefficients, t value and p value``` are not available in this condition.
* Scala/Python GLM summary should throw exception if users get ```standard error of coefficients, t value and p value``` but the underlying WLS was solved by local "l-bfgs".

## How was this patch tested?
Add unit tests.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #15930 from yanboliang/spark-18501.

(cherry picked from commit 982b82e3)
Signed-off-by: Yanbo Liang <ybliang8@gmail.com>

## What changes were proposed in this pull request?

Add model summary APIs for `GaussianMixtureModel` and `BisectingKMeansModel` in pyspark.

## How was this patch tested?

Unit tests.

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

Closes #15777 from sethah/pyspark_cluster_summaries.

(cherry picked from commit e811fbf9)
Signed-off-by: Yanbo Liang <ybliang8@gmail.com>

## What changes were proposed in this pull request?

This is a follow up to some of the discussion [here](https://github.com/apache/spark/pull/15593

). During LogisticRegression training, we store the coefficients combined with intercepts as a flat vector, but a more natural abstraction is a matrix. Here, we refactor the code to use matrix where possible, which makes the code more readable and greatly simplifies the indexing.

Note: We do not use a Breeze matrix for the cost function as was mentioned in the linked PR. This is because LBFGS/OWLQN require an implicit `MutableInnerProductModule[DenseMatrix[Double], Double]` which is not natively defined in Breeze. We would need to extend Breeze in Spark to define it ourselves. Also, we do not modify the `regParamL1Fun` because OWLQN in Breeze requires a `MutableEnumeratedCoordinateField[(Int, Int), DenseVector[Double]]` (since we still use a dense vector for coefficients). Here again we would have to extend Breeze inside Spark.

## How was this patch tested?

This is internal code refactoring - the current unit tests passing show us that the change did not break anything. No added functionality in this patch.

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

Closes #15893 from sethah/logreg_refactor.

(cherry picked from commit 856e0042)
Signed-off-by: DB Tsai <dbtsai@dbtsai.com>

[SPARK-18445][BUILD][DOCS] Fix the markdown for `Note:`/`NOTE:`/`Note that`/`'''Note:'''` across Scala/Java API documentation

It seems in Scala/Java,

- `Note:`
- `NOTE:`
- `Note that`
- `'''Note:'''`
- `note`

This PR proposes to fix those to `note` to be consistent.

**Before**

- Scala
  ![2016-11-17 6 16 39](https://cloud.githubusercontent.com/assets/6477701/20383180/1a7aed8c-acf2-11e6-9611-5eaf6d52c2e0.png)

- Java
  ![2016-11-17 6 14 41](https://cloud.githubusercontent.com/assets/6477701/20383096/c8ffc680-acf1-11e6-914a-33460bf1401d.png)

**After**

- Scala
  ![2016-11-17 6 16 44](https://cloud.githubusercontent.com/assets/6477701/20383167/09940490-acf2-11e6-937a-0d5e1dc2cadf.png)

- Java
  ![2016-11-17 6 13 39](https://cloud.githubusercontent.com/assets/6477701/20383132/e7c2a57e-acf1-11e6-9c47-b849674d4d88.png

)

The notes were found via

```bash
grep -r "NOTE: " . | \ # Note:|NOTE:|Note that|'''Note:'''
grep -v "// NOTE: " | \  # starting with // does not appear in API documentation.
grep -E '.scala|.java' | \ # java/scala files
grep -v Suite | \ # exclude tests
grep -v Test | \ # exclude tests
grep -e 'org.apache.spark.api.java' \ # packages appear in API documenation
-e 'org.apache.spark.api.java.function' \ # note that this is a regular expression. So actual matches were mostly `org/apache/spark/api/java/functions ...`
-e 'org.apache.spark.api.r' \
...
```

```bash
grep -r "Note that " . | \ # Note:|NOTE:|Note that|'''Note:'''
grep -v "// Note that " | \  # starting with // does not appear in API documentation.
grep -E '.scala|.java' | \ # java/scala files
grep -v Suite | \ # exclude tests
grep -v Test | \ # exclude tests
grep -e 'org.apache.spark.api.java' \ # packages appear in API documenation
-e 'org.apache.spark.api.java.function' \
-e 'org.apache.spark.api.r' \
...
```

```bash
grep -r "Note: " . | \ # Note:|NOTE:|Note that|'''Note:'''
grep -v "// Note: " | \  # starting with // does not appear in API documentation.
grep -E '.scala|.java' | \ # java/scala files
grep -v Suite | \ # exclude tests
grep -v Test | \ # exclude tests
grep -e 'org.apache.spark.api.java' \ # packages appear in API documenation
-e 'org.apache.spark.api.java.function' \
-e 'org.apache.spark.api.r' \
...
```

```bash
grep -r "'''Note:'''" . | \ # Note:|NOTE:|Note that|'''Note:'''
grep -v "// '''Note:''' " | \  # starting with // does not appear in API documentation.
grep -E '.scala|.java' | \ # java/scala files
grep -v Suite | \ # exclude tests
grep -v Test | \ # exclude tests
grep -e 'org.apache.spark.api.java' \ # packages appear in API documenation
-e 'org.apache.spark.api.java.function' \
-e 'org.apache.spark.api.r' \
...
```

And then fixed one by one comparing with API documentation/access modifiers.

After that, manually tested via `jekyll build`.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #15889 from HyukjinKwon/SPARK-18437.

(cherry picked from commit d5b1d5fc)
Signed-off-by: Sean Owen <sowen@cloudera.com>

## What changes were proposed in this pull request?
1, There are two `[Graph.partitionBy]` in `graphx-programming-guide.md`, the first one had no effert.
2, `DataFrame`, `Transformer`, `Pipeline` and `Parameter`  in `ml-pipeline.md` were linked to `ml-guide.html` by mistake.
3, `PythonMLLibAPI` in `mllib-linear-methods.md` was not accessable, because class `PythonMLLibAPI` is private.
4, Other link updates.
## How was this patch tested?
 manual tests

Author: Zheng RuiFeng <ruifengz@foxmail.com>

Closes #15912 from zhengruifeng/md_fix.

(cherry picked from commit cdaf4ce9)
Signed-off-by: Sean Owen <sowen@cloudera.com>