add depth for readability

Author: mengxr

mllib/src/main/scala/org/apache/spark/mllib/linalg/distributed/RowMatrix.scala

@@ -109,7 +109,7 @@ class RowMatrix(
       seqOp = (U, v) => {
         RowMatrix.dspr(1.0, v, U.data)
         U
-      }, combOp = (U1, U2) => U1 += U2, 2)
+      }, combOp = (U1, U2) => U1 += U2, depth = 2)
 
     RowMatrix.triuToFull(n, GU.data)
   }
@@ -293,7 +293,7 @@ class RowMatrix(
       seqOp = (s: (Long, BDV[Double]), v: Vector) => (s._1 + 1L, s._2 += v.toBreeze),
       combOp = (s1: (Long, BDV[Double]), s2: (Long, BDV[Double])) =>
         (s1._1 + s2._1, s1._2 += s2._2),
-      2)
+      depth = 2)
 
     updateNumRows(m)
 

mllib/src/test/scala/org/apache/spark/mllib/rdd/RDDFunctionsSuite.scala

@@ -51,16 +51,16 @@ class RDDFunctionsSuite extends FunSuite with LocalSparkContext {
     val rdd = sc.makeRDD(-1000 until 1000, 10)
     def seqOp = (c: Long, x: Int) => c + x
     def combOp = (c1: Long, c2: Long) => c1 + c2
-    for (level <- 1 until 10) {
-      val sum = rdd.treeAggregate(0L)(seqOp, combOp, level)
+    for (depth <- 1 until 10) {
+      val sum = rdd.treeAggregate(0L)(seqOp, combOp, depth)
       assert(sum === -1000L)
     }
   }
 
   test("treeReduce") {
     val rdd = sc.makeRDD(-1000 until 1000, 10)
-    for (level <- 1 until 10) {
-      val sum = rdd.treeReduce(_ + _, level)
+    for (depth <- 1 until 10) {
+      val sum = rdd.treeReduce(_ + _, depth)
       assert(sum === -1000)
     }
   }