SPARK-7137: Add checkInputColumn back to Params and print more info

Author: rekhajoshm

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

@@ -24,7 +24,8 @@ import scala.annotation.varargs
 import scala.collection.mutable
 
 import org.apache.spark.annotation.AlphaComponent
-import org.apache.spark.ml.util.Identifiable
+import org.apache.spark.ml.util.{SchemaUtils, Identifiable}
+import org.apache.spark.sql.types.{DataType, StructType}
 
 /**
  * :: AlphaComponent ::
@@ -380,6 +381,18 @@ trait Params extends Identifiable with Serializable {
     this
   }
 
+  /**
+  * Check whether the given schema contains an input column.
+  * @param colName  Input column name
+  * @param dataType  Input column DataType
+  */
+  protected def checkInputColumn(schema: StructType, colName: String, dataType: DataType): Unit = {
+    val actualDataType = schema(colName).dataType
+    SchemaUtils.checkColumnType(schema, colName, dataType)
+    require(actualDataType.equals(dataType), s"Input column Name: $colName Description: ${getParam(colName)}")
+  }
+
+
   /**
    * Gets the default value of a parameter.
    */