[SPARK-20736][Python] PySpark StringIndexer supports StringOrderType

python/pyspark/ml/feature.py

@@ -2115,22 +2115,32 @@ class StringIndexer(JavaEstimator, HasInputCol, HasOutputCol, HasHandleInvalid,
     .. versionadded:: 1.4.0
     """
 
+    stringOrderType = Param(Params._dummy(), "stringOrderType",
+                            "How to order labels of string column. The first label after " +
+                            "ordering is assigned an index of 0. Supported options: " +
+                            "frequencyDesc, frequencyAsc, alphabetDsec, alphabetAsc.",
+                            typeConverter=TypeConverters.toString)
+
     @keyword_only
-    def __init__(self, inputCol=None, outputCol=None, handleInvalid="error"):
+    def __init__(self, inputCol=None, outputCol=None, handleInvalid="error",
+                 stringOrderType="frequencyDesc"):
         """
-        __init__(self, inputCol=None, outputCol=None, handleInvalid="error")
+        __init__(self, inputCol=None, outputCol=None, handleInvalid="error", \
+                 stringOrderType="frequencyDesc")
         """
         super(StringIndexer, self).__init__()
         self._java_obj = self._new_java_obj("org.apache.spark.ml.feature.StringIndexer", self.uid)
-        self._setDefault(handleInvalid="error")
+        self._setDefault(handleInvalid="error", stringOrderType="frequencyDesc")
         kwargs = self._input_kwargs
         self.setParams(**kwargs)
 
     @keyword_only
     @since("1.4.0")
-    def setParams(self, inputCol=None, outputCol=None, handleInvalid="error"):
+    def setParams(self, inputCol=None, outputCol=None, handleInvalid="error",
+                  stringOrderType="frequencyDesc"):
         """
-        setParams(self, inputCol=None, outputCol=None, handleInvalid="error")
+        setParams(self, inputCol=None, outputCol=None, handleInvalid="error", \
+                  stringOrderType="frequencyDesc")
         Sets params for this StringIndexer.
         """
         kwargs = self._input_kwargs
@@ -2139,6 +2149,20 @@ def setParams(self, inputCol=None, outputCol=None, handleInvalid="error"):
     def _create_model(self, java_model):
         return StringIndexerModel(java_model)
 
+    @since("2.3.0")
+    def setStringOrderType(self, value):
+        """
+        Sets the value of :py:attr:`stringOrderType`.
+        """
+        return self._set(stringOrderType=value)
+
+    @since("2.3.0")
+    def getStringOrderType(self):
+        """
+        Gets the value of :py:attr:`stringOrderType` or its default value.
+        """
+        return self.getOrDefault(self.stringOrderType)
+
 
 class StringIndexerModel(JavaModel, JavaMLReadable, JavaMLWritable):
     """