overload StringArrayParam.w

Author: mengxr

mllib/src/main/scala/org/apache/spark/ml/param/params.scala

@@ -22,7 +22,7 @@ import java.util.NoSuchElementException
 
 import scala.annotation.varargs
 import scala.collection.mutable
-import scala.reflect.ClassTag
+import scala.collection.JavaConverters._
 
 import org.apache.spark.annotation.AlphaComponent
 import org.apache.spark.ml.util.Identifiable
@@ -228,7 +228,8 @@ class StringArrayParam(parent: Params, name: String, doc: String, isValid: Array
 
   override def w(value: Array[String]): ParamPair[Array[String]] = super.w(value)
 
-  private[param] def wCast(value: Seq[String]): ParamPair[Array[String]] = w(value.toArray)
+  /** Creates a param pair with a [[java.util.List]] of values (for Java and Python). */
+  def w(value: java.util.List[String]): ParamPair[Array[String]] = w(value.asScala.toArray)
 }
 
 /**
@@ -323,13 +324,7 @@ trait Params extends Identifiable with Serializable {
    * Sets a parameter in the embedded param map.
    */
   protected final def set[T](param: Param[T], value: T): this.type = {
-    shouldOwn(param)
-    if (param.isInstanceOf[StringArrayParam] && value.isInstanceOf[Seq[_]]) {
-      paramMap.put(param.asInstanceOf[StringArrayParam].wCast(value.asInstanceOf[Seq[String]]))
-    } else {
-      paramMap.put(param.w(value))
-    }
-    this
+    set(param -> value)
   }
 
   /**
@@ -339,6 +334,15 @@ trait Params extends Identifiable with Serializable {
     set(getParam(param), value)
   }
 
+  /**
+   * Sets a parameter in the embedded param map.
+   */
+  protected final def set(paramPair: ParamPair[_]): this.type = {
+    shouldOwn(paramPair.param)
+    paramMap.put(paramPair)
+    this
+  }
+
   /**
    * Optionally returns the user-supplied value of a param.
    */

python/pyspark/ml/wrapper.py

@@ -68,9 +68,8 @@ def _transfer_params_to_java(self, params, java_obj):
         for param in self.params:
             if param in paramMap:
                 value = paramMap[param]
-                if isinstance(value, list):
-                    value = _jvm().PythonUtils.toSeq(value)
-                java_obj.set(param.name, value)
+                java_param = java_obj.getParam(param.name)
+                java_obj.set(java_param.w(value))
 
     def _empty_java_param_map(self):
         """
@@ -82,7 +81,8 @@ def _create_java_param_map(self, params, java_obj):
         paramMap = self._empty_java_param_map()
         for param, value in params.items():
             if param.parent is self:
-                paramMap.put(java_obj.getParam(param.name), value)
+                java_param = java_obj.getParam(param.name)
+                paramMap.put(java_param.w(value))
         return paramMap