Dear R Users,

I have searched through the archives but I am still struggling to find a 
way to process the below dataset. I have a dataset that has stratum and 
plot identifier. Within each plot there is variable (Top) stating the 
number of measurments that should be used to to calculate the mean to the 
largest "top" elements within one of the vectors (X). I would like to 
process this summary statistic by groups. At this stage I have been trying 
to use the "summarize" function within the Hmisc library but I am getting 
the following error "Error in eval(expr, envir, enclos) : numeric 'envir' 
arg not of length one In addition: Warning message: no finite arguments to 
max; returning -Inf".

Any suggetsions on how I can fix this would be greatly appreciated.

Kind regards

Andrew

test <- read.table("test.csv", header=TRUE, sep=",")
#function to calculate mean of "top" elements within a plot
> g<-function(y) {
+ top_no <-max(y$top)
+ weight <- with(y,as.numeric(x>=x[order(x,decreasing=TRUE)[top_no]]))
+ wtd.mean(y$x,weight)
+ }
> g(test)
[1] 172.6667
#call to summarize function - use function g and summarise by stratum plot
> test.2 <- with(test,summarize(test$x,llist(test$Stratum,test$plot),g))
Error in eval(expr, envir, enclos) : numeric 'envir' arg not of length one
In addition: Warning message:
no finite arguments to max; returning -Inf 

>traceback() 
9: eval(substitute(expr), data, enclos = parent.frame())
8: with.default(y, as.numeric(x >= x[order(x, decreasing = 
TRUE)[top_no]]))
7: with(y, as.numeric(x >= x[order(x, decreasing = TRUE)[top_no]]))
6: FUN(X, ...)
5: summarize(test$x, llist(test$Stratum, test$plot), g)
4: eval(expr, envir, enclos)
3: eval(substitute(expr), data, enclos = parent.frame())
2: with.default(test, summarize(test$x, llist(test$Stratum, test$plot), 
       g))
1: with(test, summarize(test$x, llist(test$Stratum, test$plot), 
       g))

The version im running on is 

$platform
[1] "i386-pc-mingw32"

$arch
[1] "i386"

$os
[1] "mingw32"

$system
[1] "i386, mingw32"

$status
[1] ""

$major
[1] "2"

$minor
[1] "2.0"

$year
[1] "2005"

$month
[1] "10"

$day
[1] "06"

$"svn rev"
[1] "35749"

$language
[1] "R"

> 


Stratum plot     id        top     x
1       1       1       2       12
1       1       2       2       41
1       1       3       2       12
1       1       4       2       43
1       1       5       2       12
1       1       6       2       14
1       1       7       2       43
1       1       8       2       12
1       2       1       4       42
1       2       2       4       12
1       2       3       4       432
1       2       4       4       12
1       2       5       4       12
1       2       6       4       14
1       2       7       4       41
1       2       8       4       1
2       1       1       2       12
2       1       2       2       41
2       1       3       2       12
2       1       4       2       43
2       1       5       2       12
2       1       6       2       14
2       1       7       2       43
2       1       8       2       12
2       2       1       3       42
2       2       2       3       12
2       2       3       3       432
2       2       4       3       12
2       2       5       3       12
2       2       6       3       14
2       2       7       3       41
2       2       8       3       1





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