how to use try()
Check the function nlsList in package nlme. It does something very like what you want to do. "r.ghezzo" <heberto.ghezzo at mcgill.ca> writes:
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]
}
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]