R: Feature Transformation - StringIndexer

ft_string_indexer {sparklyr} | R Documentation

## Feature Transformation – StringIndexer

### Description

Encode a column of labels into a column of label indices. The indices are in [0, numLabels), ordered by label frequencies, with the most frequent label assigned index 0. The transformation can be reversed with `ft_index_to_string`.

### Usage

    ft_string_indexer(x, input.col = NULL, output.col = NULL, params = NULL,
      ...)

### Arguments

`x` | An object (usually a `spark_tbl`) coercable to a Spark DataFrame.
`input.col` | The name of the input column(s).
`output.col` | The name of the output column.
`params` | An (optional) R environment – when available, the index <-> label mapping generated by the string indexer will be injected into this environment under the `labels` key.
`...` | Optional arguments; currently unused.

### See Also

See http://spark.apache.org/docs/latest/ml-features.html for more information on the set of transformations available for DataFrame columns in Spark.

Other feature transformation routines: `ft_binarizer`, `ft_bucketizer`, `ft_discrete_cosine_transform`, `ft_elementwise_product`, `ft_index_to_string`, `ft_one_hot_encoder`, `ft_quantile_discretizer`, `ft_regex_tokenizer`, `ft_sql_transformer`, `ft_tokenizer`, `ft_vector_assembler`, `sdf_mutate`

[Package sparklyr version 0.5.4 Index]