step_regex creates a specification of a recipe step that will
create a new dummy variable based on a regular expression.
step_regex( recipe, ..., role = "predictor", trained = FALSE, pattern = ".", options = list(), result = make.names(pattern), input = NULL, skip = FALSE, id = rand_id("regex") )
A recipe object. The step will be added to the sequence of operations for this recipe.
A single selector functions to choose which variable
will be searched for the pattern. The selector should resolve
into a single variable. See
For a variable created by this step, what analysis role should they be assigned?. By default, the function assumes that the new dummy variable column created by the original variable will be used as a predictor in a model.
A logical to indicate if the quantities for preprocessing have been estimated.
A character string containing a regular
expression (or character string for
A list of options to
A single character value for the name of the new variable. It should be a valid column name.
A single character value for the name of the
variable being searched. This is
A logical. Should the step be skipped when the
recipe is baked by
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).
tidy() this step, a tibble with columns
selectors or variables selected) and
new column name) is returned.
library(modeldata) data(covers) rec <- recipe(~ description, covers) %>% step_regex(description, pattern = "(rock|stony)", result = "rocks") %>% step_regex(description, pattern = "ratake families") rec2 <- prep(rec, training = covers) rec2 #> Data Recipe #> #> Inputs: #> #> role #variables #> predictor 1 #> #> Training data contained 40 data points and no missing data. #> #> Operations: #> #> Regular expression dummy variable using `(rock|stony)` [trained] #> Regular expression dummy variable using `ratake families` [trained] with_dummies <- bake(rec2, new_data = covers) with_dummies #> # A tibble: 40 x 3 #> description rocks ratake.families #> <fct> <dbl> <dbl> #> 1 1,cathedral family,rock outcrop complex,extremely stony 1 0 #> 2 2,vanet,ratake families complex,very stony 1 1 #> 3 3,haploborolis,rock outcrop complex,rubbly 1 0 #> 4 4,ratake family,rock outcrop complex,rubbly 1 0 #> 5 5,vanet family,rock outcrop complex complex,rubbly 1 0 #> 6 6,vanet,wetmore families,rock outcrop complex,stony 1 0 #> 7 7,gothic family 0 0 #> 8 8,supervisor,limber families complex 0 0 #> 9 9,troutville family,very stony 1 0 #> 10 10,bullwark,catamount families,rock outcrop complex,ru… 1 0 #> # … with 30 more rows tidy(rec, number = 1) #> # A tibble: 1 x 3 #> terms result id #> <chr> <chr> <chr> #> 1 description NA regex_wFRUE tidy(rec2, number = 1) #> # A tibble: 1 x 3 #> terms result id #> <chr> <chr> <chr> #> 1 description rocks regex_wFRUE