[GitHub] spark pull request: [SPARK-5886][ML] Add label indexer

[jkbradley <gi...@git.apache.org>]

Github user jkbradley commented on a diff in the pull request:

    https://github.com/apache/spark/pull/4735#discussion_r27535066
  
    --- Diff: mllib/src/main/scala/org/apache/spark/ml/feature/LabelIndexer.scala ---
    @@ -0,0 +1,126 @@
    +/*
    + * Licensed to the Apache Software Foundation (ASF) under one or more
    + * contributor license agreements.  See the NOTICE file distributed with
    + * this work for additional information regarding copyright ownership.
    + * The ASF licenses this file to You under the Apache License, Version 2.0
    + * (the "License"); you may not use this file except in compliance with
    + * the License.  You may obtain a copy of the License at
    + *
    + *    http://www.apache.org/licenses/LICENSE-2.0
    + *
    + * Unless required by applicable law or agreed to in writing, software
    + * distributed under the License is distributed on an "AS IS" BASIS,
    + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    + * See the License for the specific language governing permissions and
    + * limitations under the License.
    + */
    +
    +package org.apache.spark.ml.feature
    +
    +import org.apache.spark.SparkException
    +import org.apache.spark.annotation.AlphaComponent
    +import org.apache.spark.ml.{Estimator, Model}
    +import org.apache.spark.ml.attribute.NominalAttribute
    +import org.apache.spark.ml.param._
    +import org.apache.spark.sql.DataFrame
    +import org.apache.spark.sql.functions._
    +import org.apache.spark.sql.types.{StringType, StructType}
    +import org.apache.spark.util.collection.OpenHashMap
    +
    +/**
    + * Base trait for [[LabelIndexer]] and [[LabelIndexerModel]].
    + */
    +private[feature] trait LabelIndexerBase extends Params with HasLabelCol with HasOutputCol {
    +
    +  /** Validates and transforms the input schema. */
    +  protected def validateAndTransformSchema(schema: StructType, paramMap: ParamMap): StructType = {
    +    val map = this.paramMap ++ paramMap
    +    val labelType = schema(map(labelCol)).dataType
    +    require(labelType == StringType, s"The label column must be string-typed but got $labelType.")
    +    val inputFields = schema.fields
    +    val outputColName = map(outputCol)
    +    require(inputFields.forall(_.name != outputColName),
    +      s"Output column $outputColName already exists.")
    +    val attr = NominalAttribute.defaultAttr.withName(map(outputCol))
    +    val outputFields = inputFields :+ attr.toStructField()
    +    StructType(outputFields)
    +  }
    +}
    +
    +/**
    + * :: AlphaComponent ::
    + * A label indexer that maps a string column of labels to an ML column of label indices.
    + * The indices are in [0, numLabels), ordered by label frequencies.
    + * So the most frequent label gets index 0.
    + */
    +@AlphaComponent
    +class LabelIndexer extends Estimator[LabelIndexerModel] with LabelIndexerBase {
    +
    +  /** @group setParam */
    +  def setLabelCol(value: String): this.type = set(labelCol, value)
    --- End diff --
    
    I agree


---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastructure@apache.org or file a JIRA ticket
with INFRA.
---

---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org