write.model {R2WinBUGS} | R Documentation |
Convert R / S-PLUS function to a WinBUGS model file
write.model(model, con = "model.bug")
model |
R / S-PLUS function containing the BUGS model in the BUGS model language, for minor differences see Section Details. |
con |
passed to writeLines which actually writes
the model file |
BUGS models follow closely S syntax. It is teherfore possible to write most BUGS models as R functions.
As a difference, BUGS syntax allows truncation specification like this:
dnorm(...) I(...)
but this is illegal in R and S-PLUS. To
overcome this incompatibility, use dummy operator %_%
before
I(...)
: dnorm(...) %_% I(...)
. The dummy operator
%_%
will be removed before the BUGS code is saved.
In S-PLUS, a warning is generated when the model function is defined if the last statement in the model is an assignment. To avoid this warning, add the line "invisible()" to the end of the model definition. This line will be removed before the BUGS code is saved.
Nothing, but as a side effect, the model file is written
original idea by Jouni Kerman, modified by Uwe Ligges
## Same "schoolsmodel" that is used in the examples in ?bugs: schoolsmodel <- function(){ for (j in 1:J){ y[j] ~ dnorm (theta[j], tau.y[j]) theta[j] ~ dnorm (mu.theta, tau.theta) tau.y[j] <- pow(sigma.y[j], -2) } mu.theta ~ dnorm (0.0, 1.0E-6) tau.theta <- pow(sigma.theta, -2) sigma.theta ~ dunif (0, 1000) } if (is.R()){ # for R ## some temporary filename: filename <- file.path(tempdir(), "schoolsmodel.bug") } else{ # for S-PLUS ## put the file in the working directory: filename <- "schoolsmodel.bug" } ## write model file: write.model(schoolsmodel, filename) ## and let's take a look: file.show(filename)