[SPARK-13034] PySpark ml.classification support export/import

## 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.

2 files changed, 61 insertions, 9 deletions

diff --git a/python/pyspark/ml/classification.py b/python/pyspark/ml/classification.py
index ec8834a89e..16ad76483d 100644
--- a/python/pyspark/ml/classification.py
+++ b/python/pyspark/ml/classification.py
@@ -18,7 +18,7 @@
 import warnings
 
 from pyspark import since
-from pyspark.ml.util import keyword_only
+from pyspark.ml.util import *
 from pyspark.ml.wrapper import JavaEstimator, JavaModel
 from pyspark.ml.param.shared import *
 from pyspark.ml.regression import (
@@ -38,7 +38,7 @@ __all__ = ['LogisticRegression', 'LogisticRegressionModel',
 class LogisticRegression(JavaEstimator, HasFeaturesCol, HasLabelCol, HasPredictionCol, HasMaxIter,
                          HasRegParam, HasTol, HasProbabilityCol, HasRawPredictionCol,
                          HasElasticNetParam, HasFitIntercept, HasStandardization, HasThresholds,
-                         HasWeightCol):
+                         HasWeightCol, MLWritable, MLReadable):
     """
     Logistic regression.
     Currently, this class only supports binary classification.
@@ -69,6 +69,18 @@ class LogisticRegression(JavaEstimator, HasFeaturesCol, HasLabelCol, HasPredicti
     Traceback (most recent call last):
         ...
     TypeError: Method setParams forces keyword arguments.
+    >>> lr_path = temp_path + "/lr"
+    >>> lr.save(lr_path)
+    >>> lr2 = LogisticRegression.load(lr_path)
+    >>> lr2.getMaxIter()
+    5
+    >>> model_path = temp_path + "/lr_model"
+    >>> model.save(model_path)
+    >>> model2 = LogisticRegressionModel.load(model_path)
+    >>> model.coefficients[0] == model2.coefficients[0]
+    True
+    >>> model.intercept == model2.intercept
+    True
 
     .. versionadded:: 1.3.0
     """
@@ -186,7 +198,7 @@ class LogisticRegression(JavaEstimator, HasFeaturesCol, HasLabelCol, HasPredicti
                                  " threshold (%g) and thresholds (equivalent to %g)" % (t2, t))
 
 
-class LogisticRegressionModel(JavaModel):
+class LogisticRegressionModel(JavaModel, MLWritable, MLReadable):
     """
     Model fitted by LogisticRegression.
 
@@ -589,7 +601,7 @@ class GBTClassificationModel(TreeEnsembleModels):
 
 @inherit_doc
 class NaiveBayes(JavaEstimator, HasFeaturesCol, HasLabelCol, HasPredictionCol, HasProbabilityCol,
-                 HasRawPredictionCol):
+                 HasRawPredictionCol, MLWritable, MLReadable):
     """
     Naive Bayes Classifiers.
     It supports both Multinomial and Bernoulli NB. Multinomial NB
@@ -623,6 +635,18 @@ class NaiveBayes(JavaEstimator, HasFeaturesCol, HasLabelCol, HasPredictionCol, H
     >>> test1 = sc.parallelize([Row(features=Vectors.sparse(2, [0], [1.0]))]).toDF()
     >>> model.transform(test1).head().prediction
     1.0
+    >>> nb_path = temp_path + "/nb"
+    >>> nb.save(nb_path)
+    >>> nb2 = NaiveBayes.load(nb_path)
+    >>> nb2.getSmoothing()
+    1.0
+    >>> model_path = temp_path + "/nb_model"
+    >>> model.save(model_path)
+    >>> model2 = NaiveBayesModel.load(model_path)
+    >>> model.pi == model2.pi
+    True
+    >>> model.theta == model2.theta
+    True
 
     .. versionadded:: 1.5.0
     """
@@ -696,7 +720,7 @@ class NaiveBayes(JavaEstimator, HasFeaturesCol, HasLabelCol, HasPredictionCol, H
         return self.getOrDefault(self.modelType)
 
 
-class NaiveBayesModel(JavaModel):
+class NaiveBayesModel(JavaModel, MLWritable, MLReadable):
     """
     Model fitted by NaiveBayes.
 
@@ -853,17 +877,27 @@ class MultilayerPerceptronClassificationModel(JavaModel):
 
 if __name__ == "__main__":
     import doctest
+    import pyspark.ml.classification
     from pyspark.context import SparkContext
     from pyspark.sql import SQLContext
-    globs = globals().copy()
+    globs = pyspark.ml.classification.__dict__.copy()
     # The small batch size here ensures that we see multiple batches,
     # even in these small test examples:
     sc = SparkContext("local[2]", "ml.classification tests")
     sqlContext = SQLContext(sc)
     globs['sc'] = sc
     globs['sqlContext'] = sqlContext
-    (failure_count, test_count) = doctest.testmod(
-        globs=globs, optionflags=doctest.ELLIPSIS)
-    sc.stop()
+    import tempfile
+    temp_path = tempfile.mkdtemp()
+    globs['temp_path'] = temp_path
+    try:
+        (failure_count, test_count) = doctest.testmod(globs=globs, optionflags=doctest.ELLIPSIS)
+        sc.stop()
+    finally:
+        from shutil import rmtree
+        try:
+            rmtree(temp_path)
+        except OSError:
+            pass
     if failure_count:
         exit(-1)
diff --git a/python/pyspark/ml/tests.py b/python/pyspark/ml/tests.py
index c76f893e43..9783ce7e77 100644
--- a/python/pyspark/ml/tests.py
+++ b/python/pyspark/ml/tests.py
@@ -499,6 +499,24 @@ class PersistenceTest(PySparkTestCase):
         except OSError:
             pass
 
+    def test_logistic_regression(self):
+        lr = LogisticRegression(maxIter=1)
+        path = tempfile.mkdtemp()
+        lr_path = path + "/logreg"
+        lr.save(lr_path)
+        lr2 = LogisticRegression.load(lr_path)
+        self.assertEqual(lr2.uid, lr2.maxIter.parent,
+                         "Loaded LogisticRegression instance uid (%s) "
+                         "did not match Param's uid (%s)"
+                         % (lr2.uid, lr2.maxIter.parent))
+        self.assertEqual(lr._defaultParamMap[lr.maxIter], lr2._defaultParamMap[lr2.maxIter],
+                         "Loaded LogisticRegression instance default params did not match " +
+                         "original defaults")
+        try:
+            rmtree(path)
+        except OSError:
+            pass
+
     def test_pipeline_persistence(self):
         sqlContext = SQLContext(self.sc)
         temp_path = tempfile.mkdtemp()