lgatto

##' Return the name of variable \code{varname} in call \code{match_call}.                                                                             
##'                                                                                                                                                   
##' @title Return a variable name                                                                                                                     
##' @param match_call An object of class \code{call}, as returned by \code{match.call}.                                                               
##' @param varname An \code{character} of length 1 which is looked up in \code{match_call}.                                                           
##' @return A \code{character} with the name of the variable passed as parameter                                                                      
##' \code{varname} in parent close of \code{match_call}.                                                              

lgatto

## Credit Hadley Wickham 
## http://www.mail-archive.com/[email protected]/msg125980.html
watch <- function(varname) {
 old <- get(varname)
 changed <- function(...) {
   new <- get(varname)
   if (!identical(old, new)) {
     message(varname, " is now ", new)
     old <<- new
   }

lgatto

m <- matrix(runif(1e6),nrow=10000)

## append to result vector -- slow
res1 <- NULL
t1 <- system.time(for (i in 1:1000) res1[i] <- sum(m[i,]))

## initialise to full length -- fast
res2 <- numeric(1000)
t2 <- system.time(for (i in 1:1000) res2[i] <- sum(m[i,]))

lgatto

library(MSnbase)
n <- 10000
ll <- vector("list",length=n)
e <- new.env()
tl <- system.time(for (i in 1:n)
                  ll[[i]] <- new("Spectrum2"))
te <- system.time(for (i in 1:n)
                  assign(paste("X",i,sep=""),new("Spectrum2"),e))

## Results for n=10000