Hello R and BUGS users,
I am writing a heirarchical model in R to send to BUGS via R2WinBUGS and
I am finding it difficult to get the model to run. I seem to be having
two problems.
1) I can't seem to send variables classed as factors (Month), is there a
way do this?
2) Checking the Log in WinBUGS I can see that the model is Syntactically
correct, but Bugs is not able to recognise the the initial values for
each of the chains.
I have been following the examples provided in the R vignette for
R2WinBUGS and I am a little stumped on what do do next. Any suggestions
and help will be greatly appreciated.
The Model and the R Code have been using are below. The Error from
WinBUGS is at the end of this mail.
Kind Regards
Jim Dell
Phd Candidate
Quantitative Marine Science
University of Tasmania and CSIRO Marine and Atmospheric Research
ph +62 3 6232 5182
mb +61 429 32 5182
model
{
#Centre variables
mSeaW <- mean(SeaW[])
s_dSeaW <- sd(SeaW[])
#normalise Variables
nSeaWiFS <- mSeaW/s_dSeaW
for(i in 1:N) {
log(lambda[i]) <- delta0 + alpha1 * Month[i] + alpha2 * Lat[i] +
beta1 * (SeaW[i] - nSeaW)
logit(p[i]) <- gamma0
mu[i, 1] <- 0
mu[i, 2] <- lambda[i]
mu.i[i] <- mu[i, index[i]]
index[i] ~ dcat(theta[i, 1:2])
theta[i, 1] <- p[i]
theta[i, 2] <- 1 - p[i]
# mixture
YFTCPUE[i] ~ dpois(mu.i[i])
}
# recalculate the original intercept term
Intercept <- delta0 - beta1 * nSeaW
#prior on regression coefficients
beta1 ~ dnorm(0,1.0E-6)
alpha2 ~ dnorm(0,1.0E-6)
alpha1 ~ dnorm(0, 1.0E-6)
delta0 ~ dnorm(0, 1.0E-6)
gamma0 ~ dnorm(0, 1.0E-6)
}
##R Code
library(R2WinBUGS)
library(Rlab)
#sampling functions
#get a subset of the data to use in the modelling process
LearnSamp <- function (dBUGS) # data frame of the variables of interest
{
rnames<- row.names(dBUGS)
sampRows <- sample(rnames,900)
learnSamp <- subset(dBUGS,rnames%in%sampRows)
}
#maybe not needed index.inits <- function ()
# get data into correct form for R2WinBUGS
d <-LearnSamp(dBUGS)
YFTCPUE <- d$CPUE
Month <- d$Month
Lat <- d$Lat
SeaW <- d$SeaW
N <- nrow(d)
data <- list("N", "YFTCPUE","Lat","SeaW")
#,"Month" #Month Taken out so that model runs
#create initial values for the coefficients in the model (this is model
specific)
#construct inits for the three chain
inits1 <- list(gamma0 = 0, delta0 = 0,beta1 = 0, alpha1 = 0, alpha2 = 0,
index = rbern(J,0.5)+1)
inits2 <- list(gamma0 = 0, delta0 = 0,beta1 = 0, alpha1 = 0, alpha2 = 0,
index = rbern(J,0.5)+1)
inits3 <- list(gamma0 = 0, delta0 = 0,beta1 = 0, alpha1 = 0, alpha2 = 0,
index = rbern(J,0.5)+1)
inits <- list(inits1,inits2,inits3)
## these data.frames need to be trimmed so that we can send varibles to
WinBUGS
parameters <- c("gamma0", "delta0", "beta1", "alpha1","alpha2", "index")
model <- bugs(data, inits, parameters,
model.file = "C:/Documents and Settings/del125/My Documents/PhD
data/ETBF - BUGS/CodeR2BUGS/MinusMonthSeaWiFS.bug",
codaPkg = FALSE, bugs.directory = "C:/Program Files/WinBUGS14/", debug
=TRUE)
##And the Error Message from WinBUGS
model is syntactically correct
data(C:/Program Files/R/R-2.6.0/data.txt)
data loaded
compile(3)
made use of undefined node nSeaW
inits(1,C:/Program Files/R/R-2.6.0/inits1.txt)
command #Bugs:inits cannot be executed (is greyed out)
inits(2,C:/Program Files/R/R-2.6.0/inits2.txt)
command #Bugs:inits cannot be executed (is greyed out)
inits(3,C:/Program Files/R/R-2.6.0/inits3.txt)
command #Bugs:inits cannot be executed (is greyed out)
gen.inits()
command #Bugs:gen.inits cannot be executed (is greyed out)
thin.updater(3)
update(334)
command #Bugs:update cannot be executed (is greyed out)
(error continues.....)
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