#' Feature Transformation -- VectorSlicer (Transformer)
#'
#' Takes a feature vector and outputs a new feature vector with a subarray of the original features.
#'
#' @template roxlate-ml-feature-input-output-col
#' @template roxlate-ml-feature-transformer
#' @param indices An vector of indices to select features from a vector column.
#' Note that the indices are 0-based.
#' @export
ft_vector_slicer <- function(x, input_col = NULL, output_col = NULL, indices = NULL,
uid = random_string("vector_slicer_"), ...) {
check_dots_used()
UseMethod("ft_vector_slicer")
}
ml_vector_slicer <- ft_vector_slicer
#' @export
ft_vector_slicer.spark_connection <- function(x, input_col = NULL, output_col = NULL, indices = NULL,
uid = random_string("vector_slicer_"), ...) {
.args <- list(
input_col = input_col,
output_col = output_col,
indices = indices,
uid = uid
) %>%
c(rlang::dots_list(...)) %>%
validator_ml_vector_slicer()
jobj <- spark_pipeline_stage(
x, "org.apache.spark.ml.feature.VectorSlicer",
input_col = .args[["input_col"]], output_col = .args[["output_col"]], uid = .args[["uid"]]
) %>%
jobj_set_param("setIndices", .args[["indices"]])
new_ml_vector_slicer(jobj)
}
#' @export
ft_vector_slicer.ml_pipeline <- function(x, input_col = NULL, output_col = NULL, indices = NULL,
uid = random_string("vector_slicer_"), ...) {
stage <- ft_vector_slicer.spark_connection(
x = spark_connection(x),
input_col = input_col,
output_col = output_col,
indices = indices,
uid = uid,
...
)
ml_add_stage(x, stage)
}
#' @export
ft_vector_slicer.tbl_spark <- function(x, input_col = NULL, output_col = NULL, indices = NULL,
uid = random_string("vector_slicer_"), ...) {
stage <- ft_vector_slicer.spark_connection(
x = spark_connection(x),
input_col = input_col,
output_col = output_col,
indices = indices,
uid = uid,
...
)
ml_transform(stage, x)
}
new_ml_vector_slicer <- function(jobj) {
new_ml_transformer(jobj, class = "ml_vector_slicer")
}
validator_ml_vector_slicer <- function(.args) {
.args <- validate_args_transformer(.args)
.args[["indices"]] <- cast_integer_list(.args[["indices"]], allow_null = TRUE)
.args
}
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