[SPARK-8525] [MLLIB] fix LabeledPoint parser when there is a whitespace between label and features vector

fix LabeledPoint parser when there is a whitespace between label and features vector, e.g.
(y, [x1, x2, x3])

Author: Oleksiy Dyagilev <oleksiy_dyagilev@epam.com>

Closes #6954 from fe2s/SPARK-8525 and squashes the following commits:

0755b9d [Oleksiy Dyagilev] [SPARK-8525][MLLIB] addressing comment, removing dep on commons-lang
c1abc2b [Oleksiy Dyagilev] [SPARK-8525][MLLIB] fix LabeledPoint parser when there is a whitespace on specific position

(cherry picked from commit a8031183af)
Signed-off-by: Xiangrui Meng <meng@databricks.com>

mllib/src/main/scala/org/apache/spark/mllib/util/NumericParser.scala

@@ -98,6 +98,8 @@ private[mllib] object NumericParser {
         }
       } else if (token == ")") {
         parsing = false
+      } else if (token.trim.isEmpty){
+          // ignore whitespaces between delim chars, e.g. ", ["
       } else {
         // expecting a number
         items.append(parseDouble(token))

mllib/src/test/scala/org/apache/spark/mllib/regression/LabeledPointSuite.scala

@@ -31,6 +31,11 @@ class LabeledPointSuite extends SparkFunSuite {
     }
   }
 
+  test("parse labeled points with whitespaces") {
+    val point = LabeledPoint.parse("(0.0, [1.0, 2.0])")
+    assert(point === LabeledPoint(0.0, Vectors.dense(1.0, 2.0)))
+  }
+
   test("parse labeled points with v0.9 format") {
     val point = LabeledPoint.parse("1.0,1.0 0.0 -2.0")
     assert(point === LabeledPoint(1.0, Vectors.dense(1.0, 0.0, -2.0)))

mllib/src/test/scala/org/apache/spark/mllib/util/NumericParserSuite.scala

@@ -37,4 +37,11 @@ class NumericParserSuite extends SparkFunSuite {
       }
     }
   }
+
+  test("parser with whitespaces") {
+    val s = "(0.0, [1.0, 2.0])"
+    val parsed = NumericParser.parse(s).asInstanceOf[Seq[_]]
+    assert(parsed(0).asInstanceOf[Double] === 0.0)
+    assert(parsed(1).asInstanceOf[Array[Double]] === Array(1.0, 2.0))
+  }
 }