write.model: Creating a OpenBUGS model file

Description

Convert R function to a OpenBUGS model file

Usage

write.model(model, con = "model.bug", digits = 5)

Arguments

model

R 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

digits

number of significant digits used for OpenBUGS input, see formatC

Value

Details

BUGS models follow closely S syntax. It is therefore 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. To overcome this incompatibility, use dummy operator %_% before I(...): dnorm(...) %_% I(...). The dummy operator %_% will be removed before the BUGS code is saved.

Examples

Run this code

## 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)
}

    ## some temporary filename:
    filename <- file.path(tempdir(), "schoolsmodel.bug")

## write model file:
write.model(schoolsmodel, filename)
## and let's take a look:
file.show(filename)