R help - Mar 2013 - Expressions in lattice conditional variables

I would like to have a lattice conditioning ( | var ) variable have
expression() as values because I want panel labels to be able to use
plotmath notation for subscripts, etc.   lattice barks at this.  Does anyone
know of a trick workaround?  An attempted example program is below.  Thanks
-Frank

require(lattice)
set.seed(1)
var <- c(rep('A', 100), rep('B', 100))
trt <- sample(c('T1','T2'), 200, TRUE)
x <- c(runif(100), 10*runif(100))
y <- x + c(runif(100)/10, runif(100))
N <- tapply(x, llist(var, trt), function(x) sum(!is.na(x)))
print(N)

vn <- vector('expression', length(var))
for(v in unique(var)) {
  i <- var == v
  n <- tapply(!is.na(x[i]), trt[i], sum)
  nam <- names(n)
  w <- sprintf('paste(%s,"     (",
n[%s]==%g,~~n[%s]==%g,")")',
               v, nam[1], n[1], nam[2], n[2])
  cat(w, '\n')
  vn[var == v] <- parse(text=w)
  n <- sprintf('%s      (n%s=%g, n%s=%g)', v, nam[1],n[1],
nam[2],n[2])
  vn[var == v] <- n
}
trt <- factor(trt)

xyplot(as.integer(trt) ~ x | vn, panel=panel.bpplot, ylim=c(0,3),
       scale=list(y=list(at=1:2, labels=levels(trt)),
         x=list(relation='free', limits=list(c(0,1),c(0,13)))),
       ylab='Treatment', layout=c(1,2))

Error in unique.default(x) : 
  unimplemented type 'expression' in 'HashTableSetup'




-----
Frank Harrell
Department of Biostatistics, Vanderbilt University
--
View this message in context:
http://r.789695.n4.nabble.com/Expressions-in-lattice-conditional-variables-tp4660089.html
Sent from the R help mailing list archive at Nabble.com.

Whoops - these 2 lines should have been omitted from the program:

n <- sprintf('%s      (n%s=%g, n%s=%g)', v, nam[1],n[1], nam[2],n[2])
 vn[var == v] <- n 


Frank Harrell wrote
> I would like to have a lattice conditioning ( | var ) variable have
> expression() as values because I want panel labels to be able to use
> plotmath notation for subscripts, etc.   lattice barks at this.  Does
> anyone know of a trick workaround?  An attempted example program is below. 
> Thanks -Frank
> 
> require(lattice)
> set.seed(1)
> var <- c(rep('A', 100), rep('B', 100))
> trt <- sample(c('T1','T2'), 200, TRUE)
> x <- c(runif(100), 10*runif(100))
> y <- x + c(runif(100)/10, runif(100))
> N <- tapply(x, llist(var, trt), function(x) sum(!is.na(x)))
> print(N)
> 
> vn <- vector('expression', length(var))
> for(v in unique(var)) {
>   i <- var == v
>   n <- tapply(!is.na(x[i]), trt[i], sum)
>   nam <- names(n)
>   w <- sprintf('paste(%s,"     (",
n[%s]==%g,~~n[%s]==%g,")")',
>                v, nam[1], n[1], nam[2], n[2])
>   cat(w, '\n')
>   vn[var == v] <- parse(text=w)
>   n <- sprintf('%s      (n%s=%g, n%s=%g)', v, nam[1],n[1],
nam[2],n[2])
>   vn[var == v] <- n
> }
> trt <- factor(trt)
> 
> xyplot(as.integer(trt) ~ x | vn, panel=panel.bpplot, ylim=c(0,3),
>        scale=list(y=list(at=1:2, labels=levels(trt)),
>          x=list(relation='free', limits=list(c(0,1),c(0,13)))),
>        ylab='Treatment', layout=c(1,2))
> 
> Error in unique.default(x) : 
>   unimplemented type 'expression' in 'HashTableSetup'




-----
Frank Harrell
Department of Biostatistics, Vanderbilt University
--
View this message in context:
http://r.789695.n4.nabble.com/Expressions-in-lattice-conditional-variables-tp4660089p4660090.html
Sent from the R help mailing list archive at Nabble.com.