R help - May 2004 - list & calculaton in many df subsets

Hi,

have anybody a hint /starting point how i can 
enlarge my code that's posiible for me make any  calculaton's
with variables in the  64 subset's.

Example: 
I want calculate difference of two variables inside every
of the 64 subset data.frames  and getting this value in tList!

Many thanks,
Christian


tasign <- paste("tList[[n]]  <-   try(dtree[dtree$class02 == 
paste(data$class02[n]) & dtree$class04 == paste(data$class04[n]) & 
dtree$PREDICT==paste(data$PREDICT[n]),])")
tasign <-  parse(text=tasign)[[1]]
          
for(n in 1:nrow(data)) {
  TAsign <-
do.call("substitute",list(tasign,list(n=n,X=as.name(n))))
  eval(TAsign)
}

Have you considered "lapply(by(...), ...)"?  The help for
"by" includes
an example using sapply.  See also Venables and Ripley, Modern Applied 
Statistics with S. 

hope this helps.  spencer graves

Christian Schulz wrote:
>Hi,
>
>have anybody a hint /starting point how i can 
>enlarge my code that's posiible for me make any  calculaton's
>with variables in the  64 subset's.
>
>Example: 
>I want calculate difference of two variables inside every
>of the 64 subset data.frames  and getting this value in tList!
>
>Many thanks,
>Christian
>
>
>tasign <- paste("tList[[n]]  <-   try(dtree[dtree$class02 == 
>paste(data$class02[n]) & dtree$class04 == paste(data$class04[n]) & 
>dtree$PREDICT==paste(data$PREDICT[n]),])")
>tasign <-  parse(text=tasign)[[1]]
>          
>for(n in 1:nrow(data)) {
>  TAsign <-
do.call("substitute",list(tasign,list(n=n,X=as.name(n))))
>  eval(TAsign)
>}
>
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