Re: [R] Help with Iterator
> -Original Message-
> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org]
> On Behalf Of zhiji19
> Sent: Tuesday, November 09, 2010 12:02 AM
> To: r-help@r-project.org
> Subject: [R] Help with Iterator
>
>
> Dear Experts,
>
> The following is my "Iterator". When I try to write a new function with
> itel, I got error.
>
> This is what I have:
> > supDist<-function(x,y) return(max(abs(x-y)))
> >
> > myIterator <- function(xinit,f,data=NULL,eps=1e-6,itmax=5,verbose=FALSE)
> {
> + xold<-xinit
> + itel<-0
> + repeat {
> + xnew<-f(xold,data)
> + if (verbose) {
> + cat(
> + "Iteration: ",formatC(itel,width=3, format="d"),
> + "xold: ",formatC(xold,digits=8,width=12,format="f"),
> + "xnew: ",formatC(xnew,digits=8,width=12,format="f"),
> + "\n"
> + )
> + }
> + if ((supDist(xold,xnew) < eps) || (itel == itmax)) {
> + return(xnew)
> + }
> + xold<-xnew; itel<-itel+1
> + }
> + }
>
> > mat<-function (x, data=NULL) {return (1+x^itel)}
> > myIterator(3, f=mat, verbose=TRUE)
> Error in f(xold, data) : object 'itel' not found
>
>
> Can anyone please help me to fix the error?
It appears to me that your problem is a matter of variable "scope". The error
message says that the function f cannot find object 'itel'. That is because
itel is defined in the function iterate and is local to that function. You
might want to add a third parameter to function f so you can pass in the value
of itel. (I would avoid using itel for the parameter name as you will likely
end up confusing yourself at some point). I haven't tried to figure out what
you are doing so I don't know if that is the best solution. But the problem is
that f doesn't know about object 'itel'.
Hope this is helpful,
Dan
Daniel Nordlund
Bothell, WA USA
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Re: [R] Help with Iterator
I guess what you want is:
- change the line :
xnew<-f(xold,data)
into
xnew<-f(xold,data, itel)
- change your mat function to take itel as an extra parameter:
mat<-function (x, data=NULL, itel) {return (1+x^itel)}
That should do the trick (though I haven't checked whether the rest of your
code is OK)
Nick Sabbe
--
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link: http://biomath.ugent.be
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-- Do Not Disapprove
-Original Message-
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
Behalf Of zhiji19
Sent: dinsdag 9 november 2010 9:02
To: r-help@r-project.org
Subject: [R] Help with Iterator
Dear Experts,
The following is my "Iterator". When I try to write a new function with
itel, I got error.
This is what I have:
> supDist<-function(x,y) return(max(abs(x-y)))
>
> myIterator <- function(xinit,f,data=NULL,eps=1e-6,itmax=5,verbose=FALSE) {
+ xold<-xinit
+ itel<-0
+ repeat {
+ xnew<-f(xold,data)
+ if (verbose) {
+ cat(
+ "Iteration: ",formatC(itel,width=3, format="d"),
+ "xold: ",formatC(xold,digits=8,width=12,format="f"),
+ "xnew: ",formatC(xnew,digits=8,width=12,format="f"),
+ "\n"
+ )
+ }
+ if ((supDist(xold,xnew) < eps) || (itel == itmax)) {
+ return(xnew)
+ }
+ xold<-xnew; itel<-itel+1
+ }
+ }
> mat<-function (x, data=NULL) {return (1+x^itel)}
> myIterator(3, f=mat, verbose=TRUE)
Error in f(xold, data) : object 'itel' not found
Can anyone please help me to fix the error?
--
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and provide commented, minimal, self-contained, reproducible code.
__
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
