recipes: step_invlogit – R documentation

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step_invlogit

Inverse Logit Transformation

Description

step_invlogit creates a specification of a recipe step that will transform the data from real values to be between zero and one.

Usage

step_invlogit(
  recipe,
  ...,
  role = NA,
  trained = FALSE,
  columns = NULL,
  skip = FALSE,
  id = rand_id("invlogit")
)

## S3 method for class 'step_invlogit'
tidy(x, ...)

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 which variables are affected by the step. See `selections()` for more details. For the `tidy` method, these are not currently used.
`role`	Not used by this step since no new variables are created.
`trained`	A logical to indicate if the quantities for preprocessing have been estimated.
`columns`	A character string of variable names that will be populated (eventually) by the `terms` argument.
`skip`	A logical. Should the step be skipped when the recipe is baked by `bake.recipe()`? While all operations are baked when `prep.recipe()` 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.
`x`	A `step_invlogit` object.

Details

The inverse logit transformation takes values on the real line and translates them to be between zero and one using the function f(x) = 1/(1+exp(-x)).

Value

An updated version of recipe with the new step added to the sequence of existing steps (if any). For the tidy method, a tibble with columns terms which is the columns that will be affected.

Examples

library(modeldata)
data(biomass)

biomass_tr <- biomass[biomass$dataset == "Training",]
biomass_te <- biomass[biomass$dataset == "Testing",]

rec <- recipe(HHV ~ carbon + hydrogen + oxygen + nitrogen + sulfur,
              data = biomass_tr)

ilogit_trans <- rec  %>%
  step_center(carbon, hydrogen) %>%
  step_scale(carbon, hydrogen) %>%
  step_invlogit(carbon, hydrogen)

ilogit_obj <- prep(ilogit_trans, training = biomass_tr)

transformed_te <- bake(ilogit_obj, biomass_te)
plot(biomass_te$carbon, transformed_te$carbon)

recipes

Preprocessing Tools to Create Design Matrices

v0.1.16

MIT + file LICENSE

Authors

Max Kuhn [aut, cre], Hadley Wickham [aut], RStudio [cph]

Initial release