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.
ft_string_indexer(x, input.col, output.col, params = NULL, ...)An object (usually a spark_tbl) coercable to a Spark DataFrame.
The name of the input column(s).
The name of the output column.
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 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_count_vectorizer,
ft_discrete_cosine_transform,
ft_elementwise_product,
ft_index_to_string,
ft_one_hot_encoder,
ft_quantile_discretizer,
ft_regex_tokenizer,
ft_stop_words_remover,
ft_tokenizer,
ft_vector_assembler,
sdf_mutate