Just pointing out that if you do not want to SEE an error message that is
otherwise harmless, one option in R is to let the error happen but arrange
to deal with it in some way including just suppressing the message.
On Tue, Oct 3, 2023, 5:27 AM Duncan Murdoch <murdoch.dun...@gmail.com>
wrote:
> On 02/10/2023 10:17 p.m., Trevor Davis wrote:
> > > Thanks! However, isn't length(dev.list()) == 0 when there are no
> > devices? That's what I'm seeing on MacOS.
> >
> > Ifthere is only one graphics device then R should automatically set it
> > as the active graphics device so it isn't really necessary to manually
> > set it. Although there wouldn't be any harm in manually setting it you
> > only really need to worry about setting the previous graphics device
> > when there are two or more devices open.
>
> Right, I see. With some more fiddling, I've decided that I don't like
> the error you get if you try to close device 1, so here's the current
> version:
>
> safe.dev.off <- function(which = dev.cur(), prev = dev.prev()) {
> if (which != 1) {
> force(prev)
> grDevices::dev.off(which)
> }
> if (length(dev.list()))
> dev.set(prev)
> else
> c("null device" = 1)
> }
>
> This does the dev.set even if there's only one device so it can return
> the resulting device number.
>
> Duncan Murdoch
>
> >
> > Trevor
> >
> > On Mon, Oct 2, 2023 at 5:25 PM Duncan Murdoch <murdoch.dun...@gmail.com
> > <mailto:murdoch.dun...@gmail.com>> wrote:
> >
> > Thanks! However, isn't length(dev.list()) == 0 when there are no
> > devices? That's what I'm seeing on MacOS.
> >
> > Duncan Murdoch
> >
> > On 02/10/2023 4:21 p.m., Trevor Davis wrote:
> > > > Use it just like dev.off(), but it *will* restore the previous
> > device.
> > >
> > > I'm observing that if there were no previously open graphics
> devices
> > > then your `safe.dev.off()` opens up a new graphics device which
> > may be
> > > an undesired side effect (because "surprisingly" `dev.set()` on
> > the null
> > > graphics device opens up a new graphics device). To avoid that
> you
> > > could check if `dev.list()` is greater than length 1L:
> > >
> > > safe.dev.off <- function(which = dev.cur(), prev =
> dev.prev()) {
> > > force(prev)
> > > dev.off(which)
> > > if (length(dev.list()) > 1L) {
> > > dev.set(prev)
> > > }
> > > }
> > >
> > > Trevor
> > >
> > > On Mon, Oct 2, 2023 at 11:54 AM Duncan Murdoch
> > <murdoch.dun...@gmail.com <mailto:murdoch.dun...@gmail.com>
> > > <mailto:murdoch.dun...@gmail.com
> > <mailto:murdoch.dun...@gmail.com>>> wrote:
> > >
> > > I found some weird behaviour and reported it as
> > > https://bugs.r-project.org/show_bug.cgi?id=18604
> > <https://bugs.r-project.org/show_bug.cgi?id=18604>
> > > <https://bugs.r-project.org/show_bug.cgi?id=18604
> > <https://bugs.r-project.org/show_bug.cgi?id=18604>> and
> > > https://github.com/yihui/knitr/issues/2297
> > <https://github.com/yihui/knitr/issues/2297>
> > > <https://github.com/yihui/knitr/issues/2297
> > <https://github.com/yihui/knitr/issues/2297>>, but it turns out it
> > > was user
> > > error.
> > >
> > > The dev.off() function was behaving as documented, but it
> > behaves in an
> > > unexpected (by me) way, and that caused the "bugs".
> > >
> > > The issue is that
> > >
> > > dev.off()
> > >
> > > doesn't always result in the previous graphics device being
> made
> > > current. If there are two or more other open graphics
> > devices, it
> > > won't
> > > choose the previous one, it will choose the next one.
> > >
> > > I'm letting people know because this might affect other
> > people too. If
> > > you use dev.off(), don't assume it restores the previous
> device!
> > >
> > > Here's my little workaround alternative:
> > >
> > > safe.dev.off <- function(which = dev.cur(), prev =
> > dev.prev()) {
> > > force(prev)
> > > dev.off(which)
> > > dev.set(prev)
> > > }
> > >
> > > Use it just like dev.off(), but it *will* restore the
> > previous device.
> > >
> > > Duncan Murdoch
> > >
> > > ______________________________________________
> > > R-devel@r-project.org <mailto:R-devel@r-project.org>
> > <mailto:R-devel@r-project.org <mailto:R-devel@r-project.org>>
> > mailing list
> > > https://stat.ethz.ch/mailman/listinfo/r-devel
> > <https://stat.ethz.ch/mailman/listinfo/r-devel>
> > > <https://stat.ethz.ch/mailman/listinfo/r-devel
> > <https://stat.ethz.ch/mailman/listinfo/r-devel>>
> > >
> >
>
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