R help - Feb 2012 - While loop working with TRUE/FALSE?

Hi R users,

is there any possibilty that a while loop is working like that:

z <- c(0,1,2,3,4,5,6,7,8,9)
r <- 7

   while(w == T) { 
        for ( i in 1:10 ){
                w <- r == z[i]
                print(w)  
        }
}


The loop should stop if w == TRUE


best regards

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You are combining too many loop constructs: perhaps you just want to
use for and break.

Of course, in your case it's much faster to write which(r == z) or
which.min(r == z)

Michael

On Wed, Feb 1, 2012 at 10:55 AM, Chris82 <rubenbauar at gmx.de>
wrote:
> Hi R users,
>
> is there any possibilty that a while loop is working like that:
>
> z <- c(0,1,2,3,4,5,6,7,8,9)
> r <- 7
>
> ? while(w == T) {
> ? ? ? ?for ( i in 1:10 ){
> ? ? ? ? ? ? ? ?w <- r == z[i]
> ? ? ? ? ? ? ? ?print(w)
> ? ? ? ?}
> }
>
>
> The loop should stop if w == TRUE
>
>
> best regards
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/While-loop-working-with-TRUE-FALSE-tp4348340p4348340.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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.

Le mercredi 01 f?vrier 2012 ? 07:55 -0800, Chris82 a ?crit
:
> Hi R users,
> 
> is there any possibilty that a while loop is working like that:
> 
> z <- c(0,1,2,3,4,5,6,7,8,9)
> r <- 7
> 
>    while(w == T) { 
>         for ( i in 1:10 ){
>                 w <- r == z[i]
>                 print(w)  
>         }
> }
What problem are you trying to solve? In R, loops should generally be
avoided, and you have much simpler syntax for most cases.
> The loop should stop if w == TRUE
Your while loop stops when w == FALSE here. Anyway, it won't run since w
isn't set the first time the condition is tested. And I really don't see
why you have two embedded loops here.


Cheers

On 01-02-2012, at 16:55, Chris82 wrote:
> Hi R users,
> 
> is there any possibilty that a while loop is working like that:
> 
> z <- c(0,1,2,3,4,5,6,7,8,9)
> r <- 7
> 
>   while(w == T) { 
>        for ( i in 1:10 ){
>                w <- r == z[i]
>                print(w)  
>        }
> }
> 
> 
> The loop should stop if w == TRUE
1. This won't work since the variable w doesn't exist at the start of
the while loop.
2. The while loop condition is incorrect: it should be while( w == FALSE)
3. Don't use T and F. Use TRUE and FALSE.
4. If there is no element of z equal to r the loop will run forever (with the
correct condition of course).

A much better way of doing what you seem to be wanting is

which(z == r)

or possibly

any(z == r)

Berend

Thanks to both.

This is just a simple example. In real I have two vectors with different
lengths. 
The code consists of two for loops for r and z. The main problem is the
computational time, so I try to stop the loop if w is TRUE for the first
time.

First I tried to use the command "stop" in combination with the two
for
loops, but then my whole script stoped. The script not only consists of this
stuff.



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No. The while loop is only tested after the for loop has completed. Use debug to
understand this if it doesn't make sense to you.
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Chris82 <rubenbauar at gmx.de> wrote:
>Hi R users,
>
>is there any possibilty that a while loop is working like that:
>
>z <- c(0,1,2,3,4,5,6,7,8,9)
>r <- 7
>
>   while(w == T) { 
>        for ( i in 1:10 ){
>                w <- r == z[i]
>                print(w)  
>        }
>}
>
>
>The loop should stop if w == TRUE
>
>
>best regards
>
>--
>View this message in context:
>http://r.789695.n4.nabble.com/While-loop-working-with-TRUE-FALSE-tp4348340p4348340.html
>Sent from the R help mailing list archive at Nabble.com.
>
>______________________________________________
>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 01-02-2012, at 17:32, Chris82 wrote:
> Thanks to both.
> 
> This is just a simple example. In real I have two vectors with different
> lengths. 
> The code consists of two for loops for r and z. The main problem is the
> computational time, so I try to stop the loop if w is TRUE for the first
> time.
> 
Maybe this helps:

z <- c(0,1,2,3,4,5,6,7,8,9)
r <- c(3,7)

fun1 <- function(r, z) sapply(r,function(x) which(x == z))
fun1(r,z)

Berend