How is the class called which transforms a string class label to a class index in SparkML?1 pointOneHotEncoderVectorAssemblerStringIndexerBucketizer

The class that transforms a string class label to a class index in SparkML is called StringIndexer.

Explanation:

• StringIndexer is specifically designed to map string labels to numerical indices. This is useful for machine learning algorithms that require numerical input. It assigns a unique index to each distinct label string.

• The other options have different functionalities:

  • OneHotEncoder: Converts categorical variables into a format that can be provided to ML algorithms to improve predictions.
  • VectorAssembler: Combines multiple columns into a single vector column.
  • Bucketizer: Splits a continuous feature into discrete buckets.

Thus, for converting string labels to indices, the correct answer is StringIndexer.