Interaction terms loop in R-CodePudding

Here is a small example of data. Imagine I have many more covariates than this.

install.packages("mltools")
library(mltools)
library(dplyr)
set.seed(1234)

data <- tibble::data_frame(
  age = round(runif(60, min = 48, max = 90)),
  gender = sample(c(0,1), replace=TRUE, size=60),
  weight = round(runif(60, min = 100, max = 300)),
  group = sample(letters[1:4], size = 60, replace = TRUE))

one_hot <- data[,c("group")] %>% 
  glmnet::makeX() %>%
  data.frame()
data$group <- NULL
data <- cbind(data, one_hot)

I want to create a data.frame that interacts with the group (groupa, groupb, groupc,groupd) and all variables (age, gender weight).
groupa * age
groupa * gender
groupa * weight
Same for the groupb, groupc, and groupd.

I've seen many questions about all possible interaction generators.
But I haven't seen any that show interaction with one column and the rest.
Hope this question was clear enough.

Thanks.

CodePudding user response：

I am sure there is a more elegant solution, but you could try writing your own function that does the interaction then use apply to go over the columns and do.call to combine everything:

intfun <- function(var){
  data %>% 
    mutate(across(starts_with("group"),~.*{{var}})) %>%
    select(starts_with("group"))
}

int_terms <- cbind(data, 
                   do.call(cbind, apply(data[,1:3], 2, function(x) intfun(x))))

Output (note not all columns presented here):

# > head(int_terms)
# age gender weight groupa groupb groupc groupd age.groupa age.groupb age.groupc age.groupd gender.groupa gender.groupb gender.groupc gender.groupd weight.groupa
# 1  88     33    113      0      1      0      0          0         88          0          0             0            33             0             0             0
# 2  49     33    213      1      0      0      0         49          0          0          0            33             0             0             0           213
# 3  83     33    152      1      0      0      0         83          0          0          0            33             0             0             0           152
# 4  75     33    101      0      1      0      0          0         75          0          0             0            33             0             0             0
# 5  61     33    218      0      1      0      0          0         61          0          0             0            33             0             0             0
# 6  79     33    204      1      0      0      0         79          0          0          0            33             0             0             0           204