update checkInputColumn to print more info if needed

Author: rekhajoshm

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

@@ -24,8 +24,7 @@ import scala.annotation.varargs
 import scala.collection.mutable
 
 import org.apache.spark.annotation.AlphaComponent
-import org.apache.spark.ml.util.{SchemaUtils, Identifiable}
-import org.apache.spark.sql.types.{DataType, StructType}
+import org.apache.spark.ml.util.Identifiable
 
 /**
  * :: AlphaComponent ::
@@ -381,18 +380,6 @@ 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.
    */

mllib/src/main/scala/org/apache/spark/ml/util/SchemaUtils.scala

@@ -34,10 +34,11 @@ object SchemaUtils {
    * @param colName  column name
    * @param dataType  required column data type
    */
-  def checkColumnType(schema: StructType, colName: String, dataType: DataType): Unit = {
+  def checkColumnType(schema: StructType, colName: String, dataType: DataType,
+                      msg: String = ""): Unit = {
     val actualDataType = schema(colName).dataType
     require(actualDataType.equals(dataType),
-      s"Column $colName must be of type $dataType but was actually $actualDataType.")
+      s"Column $colName must be of type $dataType but was actually $actualDataType.$msg")
   }
 
   /**