From: Henrique Dallazuanna <wwwhsd_at_gmail.com>

Date: Mon, 28 Jan 2008 13:18:21 -0200

Date: Mon, 28 Jan 2008 13:18:21 -0200

Ok, I agree, but I assume that her don't know the number of rows of file.

In your example:

rev2 <- function(x,n=100,m=5){

for(i in 1:n){

y=x[1:(length(x)-m)]

}

return(y)

}

is needed that open other textConnection - if use the example posted by me.

Is there other option?

On 28/01/2008, Barry Rowlingson <b.rowlingson_at_lancaster.ac.uk> wrote:

> Henrique Dallazuanna wrote:

*> > Perhaps:
**> >
**> > data <- read.table(textConnection(rev(rev(readLines('data.txt'))[-(1:2)])))
**> >
**>
**> Euurgh! Am I the only one whose sense of aesthetics is enraged by
**> this? To get rid of the last two items you reverse the vector, remove
**> the first two items, then reverse the vector again?
**>
**> One liners are fine for R Golf games, but in the real world, I'd get
**> the length of the vector and cut directly off the end. Consider these:
**>
**> # reverse/trim/reverse:
**> rev1 <- function(x,n=100,m=5){
**> for(i in 1:n){
**> y=rev(rev(x)[-(1:m)])
**> }
**> return(y)
**> }
**>
**> # get length, trim
**> rev2 <- function(x,n=100,m=5){
**> for(i in 1:n){
**> y=x[1:(length(x)-m)]
**> }
**> return(y)
**> }
**>
**> > system.time(rev1(1:1000,10000,5))
**> [1] 1.864 0.008 2.044 0.000 0.000
**> > system.time(rev2(1:1000,10000,5))
**> [1] 0.384 0.008 0.421 0.000 0.000
**>
**>
**> Result: faster, more directly readable code.
**>
**>
*

-- Henrique Dallazuanna Curitiba-Paraná-Brasil 25° 25' 40" S 49° 16' 22" O ______________________________________________ R-help_at_r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.Received on Mon 28 Jan 2008 - 15:41:55 GMT

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