minor updates

Author: mengxr

mllib/src/main/scala/org/apache/spark/mllib/linalg/Vectors.scala

@@ -195,10 +195,8 @@ class SparseVector(
 
   require(indices.length == values.length)
 
-  override def toString: String = {
-    Seq(size, indices.mkString("[", ",", "]"), values.mkString("[", ",", "]"))
-      .mkString("(", ",", ")")
-  }
+  override def toString: String =
+    "(%s,%s,%s)".format(size, indices.mkString("[", ",", "]"), values.mkString("[", ",", "]"))
 
   override def toArray: Array[Double] = {
     val data = new Array[Double](size)

mllib/src/main/scala/org/apache/spark/mllib/regression/LabeledPoint.scala

@@ -29,7 +29,7 @@ import org.apache.spark.SparkException
  */
 case class LabeledPoint(label: Double, features: Vector) {
   override def toString: String = {
-    Seq(label, features).mkString("(", ",", ")")
+    "(%s,%s)".format(label, features)
   }
 }