I am trying to build a function in which I have to use a comma separator between two strings to pass as formula (brmsformula needs this format to specify sigma), but I get an error because the formula does not allow a , inside it:
library(brms)
term1 <- "mpg ~ 0 + Intercept + cyl"
term2 <- "sigma ~ 0 + cyl"
formula0 <- brms::brmsformula(paste( term1, term2, sep = ', ' ))
Error in str2lang(x) : <text>:1:26: unexpected ',' 1: mpg ~ 0 +
Intercept + cyl,
^
I know I can simply pass it from terminal as:
> brms::brmsformula( mpg ~ 0 + Intercept + cyl, sigma ~ 0 + cyl )
mpg ~ 0 + Intercept + cyl
sigma ~ 0 + cyl
but I need to create it inside a function that can have (or not) sigma specifications, thus pasting these two terms (if sigma is specified).
I have googled around and looked at similar posts (like this and this) but these do not apply to my case. Does anybody know how to achieve this?
As Friede smartly suggested, looks like the solution was simply to pass multiple arguments to the formula:
> formula0 <- brms::brmsformula( term1, term2 )
mpg ~ 0 + Intercept + cyl
sigma ~ 0 + cyl