BRugs (version 0.9-2.1)

writeModel: Creating an OpenBUGS model file

Description

Convert R function to an OpenBUGS model file

Usage

writeModel(model, con = "model.txt", digits = 5)

Value

Nothing, but as a side effect, the model file is written.

Arguments

model

R function containing the BUGS model in the BUGS model language, for minor differences see Section Details.

con

passed to link{writeLines} which actually writes the model file

digits

number of significant digits used for BUGS input, see formatC

Author

original idea by Jouni Kerman, modified by Uwe Ligges

Details

The fact that bugs models follow closely to S (R) syntax is used. It should be 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 %_% before I(...): dnorm(...) %_% I(...). The dummy operator %_% will be removed before the BUGS code is saved.

See Also

modelCheck, BRugs

Examples

## Same "ratsmodel" that is used in the examples in ?BRugs and ?BRugsFit:
ratsmodel <- function(){
    for(i in 1:N){
        for(j in 1:T){
            Y[i, j] ~ dnorm(mu[i, j],tau.c)
            mu[i, j] <- alpha[i] + beta[i] * (x[j] - xbar)
        }
        alpha[i] ~ dnorm(alpha.c, alpha.tau)
        beta[i] ~ dnorm(beta.c, beta.tau)
    }
    tau.c ~ dgamma(0.001, 0.001)
    sigma <- 1 / sqrt(tau.c)
    alpha.c ~ dnorm(0.0, 1.0E-6)        
    alpha.tau ~ dgamma(0.001, 0.001)
    beta.c ~ dnorm(0.0, 1.0E-6)
    beta.tau ~ dgamma(0.001, 0.001)
    alpha0 <- alpha.c - xbar * beta.c       
}

## some temporary filename:
filename <- file.path(tempdir(), "ratsmodel.txt")
## write model file:
writeModel(ratsmodel, filename)
## and let's take a look:
file.show(filename)