[SPARK-11829] [ML] Add read/write to estimators under ml.feature (II)

[yanboliang]

Add read/write support to the following estimators under spark.ml:

• ChiSqSelector
• PCA
• VectorIndexer
• Word2Vec

[SparkQA]

Test build #46323 has finished for PR 9838 at commit 5e79781.

• This patch fails to build.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):\n * class LogisticRegressionModelWriter(instance: LogisticRegressionModel)\n * class ChiSqSelectorModelWriter(instance: ChiSqSelectorModel) extends MLWriter\n * class PCA (override val uid: String) extends Estimator[PCAModel] with PCAParams\n * class VectorIndexerModelWriter(instance: VectorIndexerModel) extends MLWriter\n * final class Word2Vec(override val uid: String) extends Estimator[Word2VecModel] with Word2VecBase\n * class Word2VecModelWriter(instance: Word2VecModel) extends MLWriter\n

[yanboliang]

Jenkins, test this please.

[SparkQA]

Test build #46326 has finished for PR 9838 at commit e3d5fc6.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):\n * class ChiSqSelectorModelWriter(instance: ChiSqSelectorModel) extends MLWriter\n * class PCA (override val uid: String) extends Estimator[PCAModel] with PCAParams\n * class VectorIndexerModelWriter(instance: VectorIndexerModel) extends MLWriter\n * final class Word2Vec(override val uid: String) extends Estimator[Word2VecModel] with Word2VecBase\n * class Word2VecModelWriter(instance: Word2VecModel) extends MLWriter\n

[SparkQA]

Test build #46327 has finished for PR 9838 at commit e3d5fc6.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):\n * class ChiSqSelectorModelWriter(instance: ChiSqSelectorModel) extends MLWriter\n * class PCA (override val uid: String) extends Estimator[PCAModel] with PCAParams\n * class VectorIndexerModelWriter(instance: VectorIndexerModel) extends MLWriter\n * final class Word2Vec(override val uid: String) extends Estimator[Word2VecModel] with Word2VecBase\n * class Word2VecModelWriter(instance: Word2VecModel) extends MLWriter\n

[yanboliang]

The same as StandardScalerModel, we can not construct PCAModel directly by specifying the variable k, so test estimator and model in one case with testEstimatorAndModelReadWrite.

[SparkQA]

Test build #46332 has finished for PR 9838 at commit ec969de.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):\n * class ChiSqSelectorModelWriter(instance: ChiSqSelectorModel) extends MLWriter\n * class PCA (override val uid: String) extends Estimator[PCAModel] with PCAParams\n * class VectorIndexerModelWriter(instance: VectorIndexerModel) extends MLWriter\n * final class Word2Vec(override val uid: String) extends Estimator[Word2VecModel] with Word2VecBase\n * class Word2VecModelWriter(instance: Word2VecModel) extends MLWriter\n

[mengxr]

Shall we keep them private[spark] for this release? We should not introduce unplanned APIs at this stage.

[mengxr]

LGTM except two minor issues commented inline.

[SparkQA]

Test build #46384 has finished for PR 9838 at commit 0cb01a3.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):\n * class ChiSqSelectorModelWriter(instance: ChiSqSelectorModel) extends MLWriter\n * class PCA (override val uid: String) extends Estimator[PCAModel] with PCAParams\n * class VectorIndexerModelWriter(instance: VectorIndexerModel) extends MLWriter\n * final class Word2Vec(override val uid: String) extends Estimator[Word2VecModel] with Word2VecBase\n * class Word2VecModelWriter(instance: Word2VecModel) extends MLWriter\n

[mengxr]

Merged into master and branch-1.6. Thanks!