Github user Krimit commented on a diff in the pull request:
https://github.com/apache/spark/pull/17673#discussion_r113600388
--- Diff: mllib/src/main/scala/org/apache/spark/ml/feature/Word2Vec.scala
---
@@ -194,6 +232,285 @@ final class Word2Vec @Since("1.4.0") (
@Since("1.4.1")
override def copy(extra: ParamMap): Word2Vec = defaultCopy(extra)
+
+ /**
+ * Similar to InitUnigramTable in the original code. Instead of using an
array of size 100 million
+ * like the original, we size it to be 20 times the vocabulary size.
+ * We sacrifice memory here, to get constant time lookups into this
array when generating
+ * negative samples.
+ */
+ private def generateUnigramTable(normalizedWeights: Array[Double],
tableSize: Int): Array[Int] = {
+ val table = Array.fill(tableSize)(0)
+ var a = 0
+ var i = 0
+ while (a < table.length) {
+ table.update(a, i)
+ if (a.toFloat / table.length >= normalizedWeights(i)) {
+ i = math.min(normalizedWeights.length - 1, i + 1)
--- End diff --
An ``if else`` here would be much more legible
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