[R] Handling interrupts in long-running R functions

[bretschr]

Dear Ivan Krylov,


Re:

> On 10 Sep 2021, at 16:43, Ivan Krylov <krylov.r00t using gmail.com> wrote:
> 
> Hello everyone,
> 
> I'm writing an R function that may be running for "long" periods of
> time (think tens of minutes), and I would like to be able to tell it:
> "please stop what you're doing and return the not-yet converged results
> as they are for inspection".
> 
> The behaviour I'm striving for is
> 
> 1) User presses interrupt
> 2) Function handles the interrupt and returns as if the convergence
>   test passed
> 3) By some black magic, the interrupt condition is raised on the
>   previous function call level (to avoid the situation where my
>   function is called in a loop by some other function and the user
>   wants to interrupt the whole process, not just my function).
> 
> Is this a good idea? Is (3) even possible? (I guess I could check the
> length of sys.parents() and avoid recovering from the interrupt if
> called from some other function, but that feels dirty.) Could something
> similar be achieved with options(error = recover) and R restarts? Are
> there other ways of, well, interrupting the execution of R functions
> without changing the semantics of interrupts in R?
> 
> I've been working with MATLAB lately (when in Rome, do as Romans
> do...), and their idiom for my desired behaviour is "create a plot
> window and return when that window is closed", but that doesn't
> translate well to R.
> 
> -- 
> Best regards,
> Ivan



Just a crazy idea: the sound input of a Mac/PC might serve as an interrupt.
Record a short bit and assess the amplitude: moderate = signal, loud = break.
See my source code below. This works on my MacBook Air with Mojave.
When I snap my fingers, the amplitude is moderate (3 through 10), when tapping 
or scratching the microphone, amplitude is over 20.

Hoping this might help,
With best regards,


Franklin
------


R source code:


#  sound as interrupt.R
#  with package audio
#  15-09-2021
#  ====================
#  NB First switch audio input to the wanted device
#     (microphone, sound input or 3rd party device)
#  flick your fingers = signal (m about 3 through 10)
#  tap the microphone -> stop  (m > 20)
library(audio)
samp.rate = 44100
rectime = 1  #  second
nsamples = samp.rate * rectime
repeat {
	sample <- record(2*nsamples, rate=44100, channels=2)
	wait(sample) # wait for the recording to finish
	sound <- sample$data # get the result
	m = max(sound)
	print(m)
	if (m > 0.5) alarm()  #  or the desired routine
	if (m > 20) {save.wave(sound, "sound from audio input.wav"); break}   # stop program
	}
#  end




Franklin Bretschneider
Dept of Biology
Utrecht University
f.bretschneider using uu.nl