Hi all,
I have written a program which performs some data simulation, model fitting (to
the simulated data) and then it will save the parameter estimates from each
loop into a matrix for later use. Because convergence will not be met in some
sets of the simulated data, I have used a 'while' instead of a
'for' loop for the job. With a 'for' loop I was not able to turn
the counter back and repeat the same loop when non-convergence occurred.
While my programme seems to be working alright, something rather odd is
happening. A sample of my programme is as follows:- (the eaxct codes in
'single quotes' have been omitted for simplicity sake)
ilim <- 10
while (i <= ilim) {
y <- 'simulated some data'
modelsummary <- try('fitted a model to the simulated data')
on.exit( c( cat("non-convergence met at loop ", i) , next) )
i <- i+1
}
When this stopped, it stopped with the warning message that I provided and the
number of i was 11. I can't figure out why it is equal to 11 because the
condition for the while loop should have failed when i became 11. The loop
should have stopped and it should not have got to the 'on.exit' bit in
the loop automatically.
While it does not seem to affect the results of my programme, I would like to
know why this quirk is happening. Any help or suggestion is more than welcome.
Thanks in advance.
Edmond
function to enable R to go to the next round once a non-convergence takes place.
On Fri, 14 Mar 2003, Edmond Ng wrote:> Hi all, > > I have written a program which performs some data simulation, model fitting (to the simulated data) and then it will save the parameter estimates from each loop into a matrix for later use. Because convergence will not be met in some sets of the simulated data, I have used a 'while' instead of a 'for' loop for the job. With a 'for' loop I was not able to turn the counter back and repeat the same loop when non-convergence occurred. > > While my programme seems to be working alright, something rather odd is happening. A sample of my programme is as follows:- (the eaxct codes in 'single quotes' have been omitted for simplicity sake) > > ilim <- 10 > while (i <= ilim) { > y <- 'simulated some data' > modelsummary <- try('fitted a model to the simulated data') > on.exit( c( cat("non-convergence met at loop ", i) , next) ) > i <- i+1 > } > > When this stopped, it stopped with the warning message that I provided > and the number of i was 11. I can't figure out why it is equal to 11 > because the condition for the while loop should have failed when i > became 11. The loop should have stopped and it should not have got to > the 'on.exit' bit in the loop automatically. >It did stop. It then exited the loop. As it was exiting, it ran the on.exit you provided. I don't know why you didn't get the error Error: No loop to break from, jumping to top level but then I don't know what your code really looked like For an example of the phenomenon that actually runs, consider f<-function () { i <- 1 while (i < 10) { on.exit(cat("exited in iteration", i, "\n")) cat(i, "\n") i <- i + 1 } } Also, the on.exit() could never do what you want, since you have prevented any non-convergence errors by using try(). You probably want something like if (inherits(modelsummary,"try-error")) {cat("convergence error",i)} but it's hard to tell. -thomas
From ?on.exit:
`on.exit' records the expression given as its argument as needing
to be executed when the current function exits (either naturally
or as the result of an error).
Thus, when "i <- i+1", it then goes to "while", which
then exits,
invoking the "on.exit" command as it does so.
Hope this helps.
Spencer Graves
Edmond Ng wrote:> Hi all,
>
> I have written a program which performs some data simulation, model fitting
(to the simulated data) and then it will save the parameter estimates from each
loop into a matrix for later use. Because convergence will not be met in some
sets of the simulated data, I have used a 'while' instead of a
'for' loop for the job. With a 'for' loop I was not able to turn
the counter back and repeat the same loop when non-convergence occurred.
>
> While my programme seems to be working alright, something rather odd is
happening. A sample of my programme is as follows:- (the eaxct codes in
'single quotes' have been omitted for simplicity sake)
>
> ilim <- 10
> while (i <= ilim) {
> y <- 'simulated some data'
> modelsummary <- try('fitted a model to the simulated data')
> on.exit( c( cat("non-convergence met at loop ", i) , next) )
> i <- i+1
> }
>
> When this stopped, it stopped with the warning message that I provided and
the number of i was 11. I can't figure out why it is equal to 11 because the
condition for the while loop should have failed when i became 11. The loop
should have stopped and it should not have got to the 'on.exit' bit in
the loop automatically.
>
> While it does not seem to affect the results of my programme, I would like
to know why this quirk is happening. Any help or suggestion is more than
welcome. Thanks in advance.
>
> Edmond
>
>
>
>
>
>
> function to enable R to go to the next round once a non-convergence takes
place.
>
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