# Re: [R] help a newbie with a loop

From: jim holtman <jholtman_at_gmail.com>
Date: Mon 03 Jul 2006 - 22:05:45 EST

You need to debug your function. If you put some 'cat(p, ind)' statements:

for (ind in 1:500)
{cat(p, ind, '\n')
res[ind,]<-powerb(x[c(1:(500-ind),(500+ind):1000)],4,0.05,0.20,0.1,m)}

Here is the place where it seemed to 'stall' on me:

```0.3 250
0.3 251
0.3 252
0.3 253
0.3 254
0.3 255
0.3 256

```

>

It looks like at this point there was probably a loop in your function. You will have to learn how to use debug to trace through what it is doing at this point. It had produced the graphs for the other values of 'p'. So there must be a 'bug' there.

On 7/3/06, Boks, M.P.M. <M.P.M.Boks@umcutrecht.nl> wrote:
>
>
>
> Hi,
>
> I am new in R and stumbled on a problem my (more experienced) friends
> can not help with with. Why isnt this code working?
>
> The function is working, also with the loop and the graph appears,
>
> only when I build another loop around it (for different values of p) ,
> R stays in a loop?
>
> Can't it take more then 2 loops in one program?
>
>
> powerb<-function(x,sp2,a,b,b1,m)
> { sx<-(sum(x^2)-(sum(x)^2)/length(x))/length(x)
> n0<-ceiling((((qnorm(1-(a/2))+qnorm(1-b))/b1)^2)*(((m+1)/m)*sp2/sx))
> repeat
> {
> n1<-ceiling((((qt(1-(a/2),n0-4)+qt(1-b,n0-4))/b1)^2)*(((m+1)/m)*sp2/sx))
> if(n0==n1) break
> n0<-n1
> }
> return(c(sx,n1))
> }
>
> x<-rnorm(1000,0,1)
> x<-x[order(x)]
>
> res<-matrix(0,1000,2)
>
>
> #use the function and plot for different values of ind and p
> for ( p in c(0.05,0.10,0.15,0.20,0.25,0.30,0.40,0.50))
> { risk<-p*(2-p)
> nonrisk<-(1-p)^2
> m<-nonrisk/risk
>
> for (ind in 1:500)
> {res[ind,]<-powerb(x[c(1:(500-ind),(500+ind):1000)],4,0.05,0.20,0.1,m)}
>
> plot(res[,1],res[,2],type="p",ylab="n",xlab="var(x)",main="b=0.1,power=0
> .80,alpha=0.05,dominant met p=0.25")}
>
>
>
> I would appreciate the help,
>
> Marco
>
>
> MPM Boks, MD PhD,
>
> Department of Psychiatry, B01.206
>
> University Medical Centre Utrecht,
>
> PO box 85500, 3508 GA Utrecht
>
> The Netherlands.
>
> Tel: +31 30 2506370
>
> Fax: +31 30 2505509
>
> Email: m.p.m.boks@umcutrecht.nl <mailto:m.p.m.boks@umcutrecht.nl>
>
>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> http://www.R-project.org/posting-guide.html
>

```--
Jim Holtman
Cincinnati, OH
+1 513 646 9390 (Cell)
+1 513 247 0281 (Home)

What is the problem you are trying to solve?

[[alternative HTML version deleted]]

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Received on Mon Jul 03 22:09:59 2006

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