from John Fox @ Mcmaster.ca
lo <-
try(nls(y~y0+a/(1+(x/x0)^b),start=list(y0=0.1,a=a0,x0=x00,b=-8.1)))
beta[i] <- if (class(lo) == "try-error") NA else lo$m$getPars()[4]
from Peter Dalgaard @ biostat.ku.dk Just check the return value from try: beta[i] <- if(inherits(try(.....),"try-error")) NA else lo$etc...
from Thomas Lumley @ u.washington.edu You want either both assignments inside the try() try({ lo<-nls(....) beta[i]<-lo$m$getPars(4) })
or both outside
lo<- try(nls(....)) if (inherits(lo,"try-error")) beta[i]<-NA else beta[i]<-lo$m$getPars()[4]
from Sundar Dorai-Raj @ pdf.com if (inherits(lo,"try-error")) beta[i]<-NA else beta[i]<-lo$m$getPars()[4]
also from Andrej Kveder @ zrc-sazu.si; Patric Burns @ pburns.seanet.com Hadley Wickham @ auckland.ac.nz;
from Douglas Bates @ stat.wisc.edu Check the function nlsList in package nlme. It does something very like what you want to do. It is not a good idea to use lo$m$getPars() directly. It is better to use the generic function, which in this case is coef(), as in coef(lo)[4]
On Mon, 09 Feb 2004 14:30:07 -0500 "r.ghezzo" <[EMAIL PROTECTED]> wrote:
Hello, I have a program with this section:
..
for(i in 1:20){
lo <-
nls(y~y0+a/(1+(x/x0)^b),start=list(y0=0.1,a=a0,x0=x00,b=-8.1))
beta[i] <- lo$m$getPars()[4]
}
..
If the fit works this is OK but if the fit fails, the whole program
fails so:
..
for(i in 1:20){
try(lo <- nls(y~y0+a/(1+(x/x0)^b),start=list(y0=0.1,a=a0,x0=x00,b=-8.1)))
beta[i] <- lo$m$getPars()[4]
}
..
but the try catches the error in nls and beta[i] gets assigned
beta[i-1] from the previous loop. This is bad but no so bad as it can
be checked,
Now in some cases the error is in i=1 and the program stops!!
is there a way to set lo$m$getPars() to zero before the call?
I tried to understand the use of tryCatch() but frankly it is above
me. Sorry
Thanks for any help
Heberto Ghezzo
Meakins-Christie Labs
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