write.model: Creating a OpenBUGS model file

In R2OpenBUGS: Running OpenBUGS from R

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

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.

Value

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

Author(s)

original idea by Jouni Kerman, modified by Uwe Ligges

See Also

bugs

Examples

## 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)

Example output

model
{
    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(0.00000E+00, 1.00000E-06)
    tau.theta <- pow(sigma.theta, -2)
    sigma.theta ~ dunif(0.00000E+00, 1000)
}

R2OpenBUGS documentation built on April 3, 2020, 1:08 a.m.