step_interact {recipes} | R Documentation |
step_interact
creates a specification of a recipe step that
will create new columns that are interaction terms between two or more
variables.
step_interact(recipe, terms, role = "predictor", trained = FALSE, objects = NULL, sep = "_x_")
recipe |
A recipe object. The step will be added to the sequence of operations for this recipe. |
terms |
A traditional R formula that contains interaction terms. |
role |
For model terms created by this step, what analysis role should they be assigned?. By default, the function assumes that the new columns created from the original variables will be used as predictors in a model. |
trained |
A logical to indicate if the quantities for preprocessing have been estimated. |
objects |
A list of |
sep |
A character value used to delinate variables in an interaction
(e.g. |
step_interact
can create interactions between variables. It
is primarily intended for numeric data; categorical variables
should probably be converted to dummy variables using
step_dummy
prior to being used for interactions.
Unlike other step functions, the terms
argument should be a
traditional R model formula but should contain no inline functions (e.g.
log
). For example, for predictors A
, B
, and C
,
a formula such as ~A:B:C
can be used to make a three way
interaction between the variables. If the formula contains terms other
than interactions (e.g. (A+B+C)^3
) only the interaction terms are
retained for the design matrix.
The separator between the variables defaults to "_x_
" so that the
three way interaction shown previously would generate a column named
A_x_B_x_C
. This can be changed using the sep
argument.
An updated version of recipe
with the
new step added to the sequence of existing steps (if any).
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) int_mod_1 <- rec %>% step_interact(terms = ~ carbon:hydrogen) int_mod_2 <- int_mod_1 %>% step_interact(terms = ~ (oxygen + nitrogen + sulfur)^3) int_mod_1 <- prep(int_mod_1, training = biomass_tr) int_mod_2 <- prep(int_mod_2, training = biomass_tr) dat_1 <- bake(int_mod_1, biomass_te) dat_2 <- bake(int_mod_2, biomass_te) names(dat_1) names(dat_2)