Dear R Users,

I am trying to write a wrapper around summarize and xYplot from Hmisc  
and am having trouble understanding how to pass arguments from the  
function I am writing to the nested functions.

There must be a way, but I have not been able to figure it out.

An example is below.

Any advice would be greatly appreciated.

Thanks, Dan





# some example data
df=expand.grid(rep=1:4, fac1=c("a","b"), fac2=c("c","d"), fac3=c 
("e","f"))
df$resp1=rnorm(length(df$fac1))
df

# define a funciton to compute mean, std error and n.
meanstderr <- function(x) c(Mean=mean(x,na.rm=TRUE),se=sqrt(var 
(x,na.rm=TRUE)/length(na.omit(x))), n=length(na.omit(x)))


#  what I want to wrap into a single funtction:
sumdf=with(df, summarize(X=resp1, by=llist(fac1, fac2, fac3),  
stat.name="resp1", FUN=meanstderr))
xYplot(Cbind(resp1, resp1-se, resp1+se) ~ as.numeric(fac1)|fac2,  
groups=fac3, data=sumdf, type='b',
scales=list(x=list(labels=levels(df$fac1), at=1:length(levels(df 
$fac1)))), xlim=c(0,length(levels(df$fac1))+1))	

# here is a function to make the call to "summarize", but I cannot  
understand how to pass the arguments to "summarize"
# I've tried passing them as names, text and vectors, but to no avail
xYerrbar=function(formula, data = sys.frame(sys.parent()), groups,  
subset,
     xlab = NULL, ylab = NULL, ylim = NULL, panel = panel.xYplot,
     prepanel = prepanel.xYplot, scales = NULL, minor.ticks = NULL,
     ...)
{ # data=df; groups=fac2
	require("Hmisc")
     require("grid")
     require("lattice")
     ytext <- as.character(formula[2])
     yvname <- formula[[2]]
     y <- eval(parse(text = ytext), data)
     xexp <- formula[[3]]
     if (length(xexp) > 1 && as.character(xexp[[1]]) == "|") {
         xvname <- xexp[[2]]
         byname <- xexp[[3]]
         xtext <- as.character(xexp[2])
         bynametext <- as.character(xexp[3])
         }
         else {xvname <- xexp; xtext <- as.character(xexp)}
     xv <- eval(xvname, data)
     byfac <- eval(byname, data)
     if (!missing(groups))
         {groups <- eval(substitute(groups), data)}
# none of the below seem to work
	sumdf1=do.call("summarize", args=list(X=y, by=llist(xvname),  
FUN=meanstderr))
	sumdf2=do.call("summarize", args=list(X=y, by=xv, FUN=meanstderr))
	sumdf4=summarize(y, by=llist(xv), FUN=meanstderr)
}

xYerrbar(formula=resp1~fac2|fac1,  data=df, groups=fac3)







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