viirya commented on a change in pull request #20146: [SPARK-11215][ML] Add
multiple columns support to StringIndexer
URL: https://github.com/apache/spark/pull/20146#discussion_r244529384
##########
File path: mllib/src/main/scala/org/apache/spark/ml/feature/StringIndexer.scala
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@@ -130,21 +166,78 @@ class StringIndexer @Since("1.4.0") (
@Since("1.4.0")
def setOutputCol(value: String): this.type = set(outputCol, value)
+ /** @group setParam */
+ @Since("3.0.0")
+ def setInputCols(value: Array[String]): this.type = set(inputCols, value)
+
+ /** @group setParam */
+ @Since("3.0.0")
+ def setOutputCols(value: Array[String]): this.type = set(outputCols, value)
+
+ private def countByValue(
+ dataset: Dataset[_],
+ inputCols: Array[String]): Array[OpenHashMap[String, Long]] = {
+
+ val aggregator = new StringIndexerAggregator(inputCols.length)
+ implicit val encoder = Encoders.kryo[Array[OpenHashMap[String, Long]]]
+
+ val selectedCols = inputCols.map { colName =>
+ val col = dataset.col(colName)
+ if (col.expr.dataType == StringType) {
+ col
+ } else {
+ // We don't count for NaN values. Because `StringIndexerAggregator`
only processes strings,
+ // we replace NaNs with null in advance.
+ new Column(If(col.isNaN.expr, Literal(null),
col.expr)).cast(StringType)
Review comment:
Replaced NaNs with null for numeric type inputs. Then
`StringIndexerAggregator` will skip null when doing aggregation.
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