R help - Oct 2008 - Trying to pass arrays as arguments to a function

I'd like to avoid looping through an array in order to change values in
the array as it takes too long.
I red from an earlier post it can be done by "do.call" but never got
it
to work. The Idea is to change the value of "y" according to values in
"x". Wherever "x" holds the value 3, the corresponding value
in "y"
should be set to 1. 

So I tried the following giving an error message:

#################
x <- c(1,2,3,2,2,3,1,1,3,3)
y <- c(0,0,1,1,0,0,1,0,0,1)

Change_y <- function() {

if (x == 3) {y <- 1}
  
}

do.call("Change_y", as.list(x,y))

Error in Change_y(1, 2, 3, 2, 2, 3, 1, 1, 3, 3) :
        unused argument(s) ( ...)

##################

How should it be done?

Cheers,
Kare

	[[alternative HTML version deleted]]

y <- ifelse(x == 3, 1, y)

-Kaom

On Oct 20, 2008, at 6:07 AM, K?re Edvardsen wrote:
> I'd like to avoid looping through an array in order to change values  
> in
> the array as it takes too long.
> I red from an earlier post it can be done by "do.call" but never
got
> it
> to work. The Idea is to change the value of "y" according to
values in
> "x". Wherever "x" holds the value 3, the corresponding
value in "y"
> should be set to 1.
>
> So I tried the following giving an error message:
>
> #################
> x <- c(1,2,3,2,2,3,1,1,3,3)
> y <- c(0,0,1,1,0,0,1,0,0,1)
>
> Change_y <- function() {
>
> if (x == 3) {y <- 1}
>
> }
>
> do.call("Change_y", as.list(x,y))
>
> Error in Change_y(1, 2, 3, 2, 2, 3, 1, 1, 3, 3) :
>        unused argument(s) ( ...)
>
> ##################
>
> How should it be done?
>
> Cheers,
> Kare
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> 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.

On Mon, Oct 20, 2008 at 03:07:45PM +0200, K?re Edvardsen
wrote:
> I'd like to avoid looping through an array in order to change values in
> the array as it takes too long.
> I red from an earlier post it can be done by "do.call" but never
got it
> to work. The Idea is to change the value of "y" according to
values in
> "x". Wherever "x" holds the value 3, the corresponding
value in "y"
> should be set to 1. 
This should do what you want - no looping required:

y[x==3] <- 1

cu
	Philipp

-- 
Dr. Philipp Pagel
Lehrstuhl f?r Genomorientierte Bioinformatik
Technische Universit?t M?nchen
Wissenschaftszentrum Weihenstephan
85350 Freising, Germany
http://mips.gsf.de/staff/pagel

> I'd like to avoid looping through an array in order to change values in
> the array as it takes too long.
> I red from an earlier post it can be done by "do.call" but never
got it
> to work. The Idea is to change the value of "y" according to
values in
> "x". Wherever "x" holds the value 3, the corresponding
value in "y"
> should be set to 1.
y [x == 3] <- 1


-- 
Claudia Beleites
Dipartimento dei Materiali e delle Risorse Naturali
Universit? degli Studi di Trieste
Via Alfonso Valerio 6/a
I-34127 Trieste

phone: +39 (0 40) 5 58-34 47
email: cbeleites at units.it