step_slice creates a specification of a recipe step
that will filter rows using
step_slice( recipe, ..., role = NA, trained = FALSE, inputs = NULL, skip = TRUE, id = rand_id("slice") )
A recipe object. The step will be added to the sequence of operations for this recipe.
Integer row values. See
Not used by this step since no new variables are created.
A logical to indicate if the quantities for preprocessing have been estimated.
Quosure of values given by
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 any existing operations.
When an object in the user's global environment is
referenced in the expression defining the new variable(s),
it is a good idea to use quasiquotation (e.g.
to embed the value of the object in the expression (to
be portable between sessions). See the examples.
tidy() this step, a tibble with column
contains the filtering indices is returned.
This step can entirely remove observations (rows of data), which can have
unintended and/or problematic consequences when applying the step to new
data later via
bake.recipe(). Consider whether
skip = TRUE or
skip = FALSE is more appropriate in any given use case. In most instances
that affect the rows of the data being predicted, this step probably should
not be applied at all; instead, execute operations like this outside and
before starting a preprocessing
rec <- recipe( ~ ., data = iris) %>% step_slice(1:3) prepped <- prep(rec, training = iris %>% slice(1:75)) tidy(prepped, number = 1) #> # A tibble: 1 × 2 #> terms id #> <chr> <chr> #> 1 1:3 slice_FPmAy library(dplyr) dplyr_train <- iris %>% as_tibble() %>% slice(1:75) %>% slice(1:3) rec_train <- bake(prepped, new_data = NULL) all.equal(dplyr_train, rec_train) #>  TRUE dplyr_test <- iris %>% as_tibble() %>% slice(76:150) %>% slice(1:3) rec_test <- bake(prepped, iris %>% slice(76:150)) all.equal(dplyr_test, rec_test) #>  "Attributes: < Component “row.names”: Numeric: lengths (3, 75) differ >" #>  "Component “Sepal.Length”: Numeric: lengths (3, 75) differ" #>  "Component “Sepal.Width”: Numeric: lengths (3, 75) differ" #>  "Component “Petal.Length”: Numeric: lengths (3, 75) differ" #>  "Component “Petal.Width”: Numeric: lengths (3, 75) differ" #>  "Component “Species”: Lengths: 3, 75" #>  "Component “Species”: Lengths (3, 75) differ (string compare on first 3)" # Embedding the integer expression (or vector) into the # recipe: keep_rows <- 1:6 qq_rec <- recipe( ~ ., data = iris) %>% # Embed `keep_rows` in the call using !! step_slice(!!keep_rows) %>% prep(training = iris) tidy(qq_rec, number = 1) #> # A tibble: 1 × 2 #> terms id #> <chr> <chr> #> 1 1:6 slice_xhh4Y