Make sure that an incadata object has an id identifying the patient.
id(x, id = c("persnr", "pnr", "pat_id", "pn", "id"), ignore.case = TRUE)
data.frame
names of possible id variable found in x
should name matching be done regardless of character case?
Character variable with either the first name from id
found in
x
or rownames(x)
if no named column found.