[SPARK-6893][ML] default pipeline parameter handling in python

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

1 files changed, 50 insertions, 2 deletions

diff --git a/python/pyspark/ml/tests.py b/python/pyspark/ml/tests.py
index b627c2b4e9..3a42bcf723 100644
--- a/python/pyspark/ml/tests.py
+++ b/python/pyspark/ml/tests.py
@@ -33,6 +33,7 @@ else:
 from pyspark.tests import ReusedPySparkTestCase as PySparkTestCase
 from pyspark.sql import DataFrame
 from pyspark.ml.param import Param
+from pyspark.ml.param.shared import HasMaxIter, HasInputCol
 from pyspark.ml.pipeline import Transformer, Estimator, Pipeline
 
 
@@ -46,7 +47,7 @@ class MockTransformer(Transformer):
 
     def __init__(self):
         super(MockTransformer, self).__init__()
-        self.fake = Param(self, "fake", "fake", None)
+        self.fake = Param(self, "fake", "fake")
         self.dataset_index = None
         self.fake_param_value = None
 
@@ -62,7 +63,7 @@ class MockEstimator(Estimator):
 
     def __init__(self):
         super(MockEstimator, self).__init__()
-        self.fake = Param(self, "fake", "fake", None)
+        self.fake = Param(self, "fake", "fake")
         self.dataset_index = None
         self.fake_param_value = None
         self.model = None
@@ -111,5 +112,52 @@ class PipelineTests(PySparkTestCase):
         self.assertEqual(6, dataset.index)
 
 
+class TestParams(HasMaxIter, HasInputCol):
+    """
+    A subclass of Params mixed with HasMaxIter and HasInputCol.
+    """
+
+    def __init__(self):
+        super(TestParams, self).__init__()
+        self._setDefault(maxIter=10)
+
+
+class ParamTests(PySparkTestCase):
+
+    def test_param(self):
+        testParams = TestParams()
+        maxIter = testParams.maxIter
+        self.assertEqual(maxIter.name, "maxIter")
+        self.assertEqual(maxIter.doc, "max number of iterations")
+        self.assertTrue(maxIter.parent is testParams)
+
+    def test_params(self):
+        testParams = TestParams()
+        maxIter = testParams.maxIter
+        inputCol = testParams.inputCol
+
+        params = testParams.params
+        self.assertEqual(params, [inputCol, maxIter])
+
+        self.assertTrue(testParams.hasDefault(maxIter))
+        self.assertFalse(testParams.isSet(maxIter))
+        self.assertTrue(testParams.isDefined(maxIter))
+        self.assertEqual(testParams.getMaxIter(), 10)
+        testParams.setMaxIter(100)
+        self.assertTrue(testParams.isSet(maxIter))
+        self.assertEquals(testParams.getMaxIter(), 100)
+
+        self.assertFalse(testParams.hasDefault(inputCol))
+        self.assertFalse(testParams.isSet(inputCol))
+        self.assertFalse(testParams.isDefined(inputCol))
+        with self.assertRaises(KeyError):
+            testParams.getInputCol()
+
+        self.assertEquals(
+            testParams.explainParams(),
+            "\n".join(["inputCol: input column name (undefined)",
+                       "maxIter: max number of iterations (default: 10, current: 100)"]))
+
+
 if __name__ == "__main__":
     unittest.main()