From dbb0a4b263bc7ac8bcd80151a4c8b122de199da0 Mon Sep 17 00:00:00 2001
From: denon1 <gardnerjens@gmail.com>
Date: Sat, 1 Apr 2023 11:43:44 +0200
Subject: [PATCH] Change uses fold over foreach now

---
 .../EigenVectorsForSparseSymmetric.scala      | 25 ++++++++-----------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/src/scala/com/twitter/simclusters_v2/scalding/EigenVectorsForSparseSymmetric.scala b/src/scala/com/twitter/simclusters_v2/scalding/EigenVectorsForSparseSymmetric.scala
index 7171e0e7a..98313ba4a 100644
--- a/src/scala/com/twitter/simclusters_v2/scalding/EigenVectorsForSparseSymmetric.scala
+++ b/src/scala/com/twitter/simclusters_v2/scalding/EigenVectorsForSparseSymmetric.scala
@@ -44,22 +44,17 @@ object EigenVectorsForSparseSymmetric {
    * @return the constructed matrix
    */
   def getMatrix(nonzeros: Iterable[(Int, Int, Double)], nRows: Int, nCols: Int): Matrix = {
-    val matrix = new LinkedSparseMatrix(nRows, nCols)
-    var numEntries = 0
-    var maxRow = 0
-    var maxCol = 0
-
-    nonzeros.foreach {
-      case (i, j, v) =>
-        if (i > maxRow) {
-          maxRow = i
-        }
-        if (j > maxCol) {
-          maxCol = j
-        }
-        numEntries += 1
-        matrix.set(i, j, v)
+    val baseCase = (new LinkedSparseMatrix(nRows, nCols), 0, 0, 0)
+    val partialNonzeros = nonzeros.foldRight(baseCase)
+    val (matrix, numEntries, maxRow, maxCol) = partialNonzeros{
+      case ((i, j, v), (matrix, numEntries, maxRow, maxCol) ) => (i, j) match {
+        case (_, _) if (i > maxRow) && (j > maxCol) => (matrix.set(i, j, v), (numEntries += 1, i, j))
+        case (_, _) if (i > maxRow) => (matrix.set(i, j, v), (numEntries += 1, i, maxCol))
+        case (_, _) if (j > maxCol) => (matrix.set(i, j, v), (numEntries += 1, maxRow, j))
+        case (_, _) => (matrix.set(i, j, v), (numEntries += 1, maxRow, maxCol))
+      }
     }
+
     log.info(
       "Finished building matrix with %d entries and maxRow %d and maxCol %d"
         .format(numEntries, maxRow, maxCol))