step_center {recipes} | R Documentation |
step_center
creates a specification of a recipe step that
will normalize numeric data to have a mean of zero.
step_center(recipe, ..., role = NA, trained = FALSE, means = NULL, na.rm = TRUE)
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 |
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. |
means |
A named numeric vector of means. This is |
na.rm |
A logical value indicating whether |
Centering data means that the average of a variable is subtracted
from the data. step_center
estimates the variable means from the
data used in the training
argument of prep.recipe
.
bake.recipe
then applies the centering to new data sets using
these means.
An updated version of recipe
with the
new step added to the sequence of existing steps (if any).
recipe
prep.recipe
bake.recipe
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) center_trans <- rec %>% step_center(carbon, contains("gen"), -hydrogen) center_obj <- prep(center_trans, training = biomass_tr) transformed_te <- bake(center_obj, biomass_te) biomass_te[1:10, names(transformed_te)] transformed_te