step_tomek creates a specification of a recipe
step that removes majority class instances of tomek links. Using
step_tomek( recipe, ..., role = NA, trained = FALSE, column = NULL, skip = TRUE, seed = sample.int(10^5, 1), id = rand_id("tomek") ) # S3 method for step_tomek tidy(x, ...)
A recipe object. The step will be added to the sequence of operations for this recipe.
One or more selector functions to choose which
variable is used to sample the data. See
Not used by this step since no new variables are created.
A logical to indicate if the quantities for preprocessing have been estimated.
A character string of the variable name that will
be populated (eventually) by the
A logical. Should the step be skipped when the
recipe is baked by
An integer that will be used as the seed when applied.
A character string that is unique to this step to identify it.
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 variable used to sample.
The factor variable used to balance around must only have 2 levels. All other variables must be numerics with no missing data.
A tomek link is defined as a pair of points from different classes and are each others nearest neighbors.
When used in modeling, users should strongly consider using the
skip = TRUE so that the extra sampling is not
conducted outside of the training set.
Tomek. Two modifications of cnn. IEEE Trans. Syst. Man Cybern., 6:769-772, 1976.
#> #> <NA> stem other #> 0 9539 50316ds_rec <- recipe(Class ~ age + height, data = okc) %>% step_meanimpute(all_predictors()) %>% step_tomek(Class) %>% prep() sort(table(bake(ds_rec, new_data = NULL)$Class, useNA = "always"))#> #> <NA> stem other #> 0 9539 49710# since `skip` defaults to TRUE, baking the step has no effect baked_okc <- bake(ds_rec, new_data = okc) table(baked_okc$Class, useNA = "always")#> #> stem other <NA> #> 9539 50316 0library(ggplot2) ggplot(circle_example, aes(x, y, color = class)) + geom_point() + labs(title = "Without Tomek") + xlim(c(1, 15)) + ylim(c(1, 15))recipe(class ~ ., data = circle_example) %>% step_tomek(class) %>% prep() %>% bake(new_data = NULL) %>% ggplot(aes(x, y, color = class)) + geom_point() + labs(title = "With Tomek") + xlim(c(1, 15)) + ylim(c(1, 15))