On 12/06/2014 02:53 PM, ce wrote:
Dear all,
Let's say I have this script , below. tryCatch indeed catches the error but
exists, I want function to continue and stay in the loop. I found very
examples of withRestarts on internet to figure it out. Could you help me how to
do it ?
myfunc <- function()
{
while(1)
{
x <- runif(1)
if ( x > 0.3 ) a <- x/2 else a <- x/"b"
print(a)
Sys.sleep(1)
}
}
Hi --
Modify your function so that the code that you'd like to restart after is
surrounded with withRestarts(), and with a handler that performs the action
you'd like, so
myfunc <- function()
{
while(TRUE)
{
x <- runif(1)
withRestarts({
if ( x > 0.3 ) a <- x/2 else a <- x/"b"
print(a)
}, restartLoop = function() {
message("restarting")
NULL
})
Sys.sleep(1)
}
}
Instead of using tryCatch(), which returns to the top level context to evaluate
the handlers, use withCallingHandlers(), which retains the calling context.
Write a handler that invokes the restart
withCallingHandlers({
myfunc()
}, error = function(e) {
message("error")
invokeRestart("restartLoop")
})
It's interesting that tryCatch is usually used with errors (because errors are
hard to recover from), and withCallingHandlers are usually used with warnings
(because warnings can usually be recovered from), but tryCatch() and
withCallingHandlers() can be used with any condition.
Martin
tryCatch({ myfunc() },
warning = function(w) { print("warning") },
error = function(e) { print("error") },
finally = { print("end") }
)
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______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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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.
