A Transformer that maps a column of indices back to a new column of corresponding string values. The index-string mapping is either from the ML attributes of the input column, or from user-supplied labels (which take precedence over ML attributes). This function is the inverse of ft_string_indexer.

  input_col = NULL,
  output_col = NULL,
  labels = NULL,
  uid = random_string("index_to_string_"),



A spark_connection, ml_pipeline, or a tbl_spark.


The name of the input column.


The name of the output column.


Optional param for array of labels specifying index-string mapping.


A character string used to uniquely identify the feature transformer.


Optional arguments; currently unused.


The object returned depends on the class of x.

  • spark_connection: When x is a spark_connection, the function returns a ml_transformer, a ml_estimator, or one of their subclasses. The object contains a pointer to a Spark Transformer or Estimator object and can be used to compose Pipeline objects.

  • ml_pipeline: When x is a ml_pipeline, the function returns a ml_pipeline with the transformer or estimator appended to the pipeline.

  • tbl_spark: When x is a tbl_spark, a transformer is constructed then immediately applied to the input tbl_spark, returning a tbl_spark

See also