srowen 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_r245676396
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File path: mllib/src/main/scala/org/apache/spark/ml/feature/StringIndexer.scala
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@@ -172,37 +274,77 @@ object StringIndexer extends
DefaultParamsReadable[StringIndexer] {
@Since("1.6.0")
override def load(path: String): StringIndexer = super.load(path)
+
+ // Returns a function used to sort strings by frequency (ascending or
descending).
+ // In case of equal frequency, it sorts strings by alphabet (ascending).
+ private[feature] def getSortFunc(
+ ascending: Boolean): ((String, Long), (String, Long)) => Boolean = {
+ if (ascending) {
+ (a: (String, Long), b: (String, Long)) => {
+ if (a._2 == b._2) {
+ a._1 < b._1
+ } else {
+ a._2 < b._2
+ }
+ }
+ } else {
+ (a: (String, Long), b: (String, Long)) => {
+ if (a._2 == b._2) {
+ a._1 < b._1
+ } else {
+ a._2 > b._2
+ }
+ }
+ }
+ }
}
/**
* Model fitted by [[StringIndexer]].
*
- * @param labels Ordered list of labels, corresponding to indices to be
assigned.
+ * @param labelsArray Array of ordered list of labels, corresponding to
indices to be assigned
+ * for each input column.
*
- * @note During transformation, if the input column does not exist,
- * `StringIndexerModel.transform` would return the input dataset unmodified.
+ * @note During transformation, if any input column does not exist,
+ * `StringIndexerModel.transform` would skip the input column.
+ * If all input columns do not exist, it returns the input dataset unmodified.
* This is a temporary fix for the case when target labels do not exist during
prediction.
*/
@Since("1.4.0")
class StringIndexerModel (
@Since("1.4.0") override val uid: String,
- @Since("1.5.0") val labels: Array[String])
+ @Since("3.0.0") val labelsArray: Array[Array[String]])
extends Model[StringIndexerModel] with StringIndexerBase with MLWritable {
import StringIndexerModel._
+ @deprecated("`this(labels: Array[String])` is deprecated and will be removed
in 3.1.0. " +
Review comment:
I think it's still valid to index one column; I don't see a need to
deprecate or remove this? it can just call the other constructor
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