Nystrom kernel feature map approximation (RBF)

step_kfm_nystrom() creates a specification of a recipe step that will convert numeric data into a feature appoximation. nystrom approximates the 'radial' kernel approximation.

Usage

step_kfm_nystrom(
  recipe,
  ...,
  role = "predictor",
  trained = FALSE,
  res = NULL,
  columns = NULL,
  sigma = 0.2,
  m = NULL,
  r = NULL,
  sampling = "random",
  prefix = "kFM",
  keep_original_cols = FALSE,
  skip = FALSE,
  id = rand_id("kfm_nystrom")
)

Arguments

recipe: A recipe object. The step will be added to the sequence of operations for this recipe.
...: One or more selector functions to choose variables for this step. See selections() for more details.
role: For model terms created by this step, what analysis role should they be assigned? By default, the new columns created by this step from the original variables will be used as predictors in a model.
trained: A logical to indicate if the quantities for preprocessing have been estimated.
res: An mildsvm::kfm_nystrom() object is stored here once this preprocessing step has be trained by prep().
columns: A character string of the selected variable names. This field is a placeholder and will be populated once prep() is used.
sigma: A numeric value for the nystrom function parameter.
m: The number rows from df to sample in fitting. defaults to nrow of data
r: The rank of matrix approximation to use. Must be less than or equal to m, the default.
prefix: A character string for the prefix of the resulting new variables. See notes below.
keep_original_cols: A logical to keep the original variables in the output. Defaults to FALSE.
skip: A logical. Should the step be skipped when the recipe is baked by bake()? While all operations are baked when prep() is run, some operations may not be able to be conducted on new data (e.g. processing the outcome variable(s)). Care should be taken when using skip = TRUE as it may affect the computations for subsequent operations.
id: A character string that is unique to this step to identify it.

Usage

Arguments

See also