Creates the disease-related age covariate vector based on the disease initiation times and adds it to the data frame

add_dis_age(data, t_init, id_var = "id", time_var = "age")

## Arguments

data the original data frame A named vector containing the observed initiation or onset time for each individual. The names, i.e. names(t_init), should specify the individual id. name of the id variable in data name of the time variable in data

## Value

A data frame with one column added. The new column will be called dis_age. For controls, its value will be NaN.

Other data frame handling functions: add_factor_crossing(), add_factor(), adjusted_c_hat(), new_x(), split()