Easily add a categorical covariate to a data frame
add_factor(data, x, id_var = "id")the original data frame
A named vector containing the category for each individual. The names should specify the individual id.
name of the id variable in data
A data frame with one column added. The new column will
have same name as the variable passed as input x.
Other data frame handling functions:
add_dis_age(),
add_factor_crossing(),
adjusted_c_hat(),
new_x(),
split()