[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.

1 files changed, 18 insertions, 0 deletions

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()