R: Offer 5 seconds to demand a pause. If no pause demanded, resume the process

Question

How can I offer 5 seconds to the user to write something in order to ask for a pause of indefinite length. If the pause is not demanded within these 5 seconds, the process continues. If a pause is demanded, then the user has all the time (s)he needs and (s)he can hit "enter" in order to resume the process whenever (s)he wants.

The interest of such functionality is that if the user is absent, the pause lasts for 5 seconds only. And if the user is present, then (s)he can enjoy a pause in order to watch the graph that has been produced for example.

The code may eventually look like that:

DoYouWantaPause = function(){
   myprompt = "You have 5 seconds to write the letter <p>. If you don't the process will go on."

   foo = readline(prompt = myprompt, killAfter = 5 Seconds)    # give 5 seconds to the user. If the user enter a letter, then this letter is stored in `foo`.

   if (foo == "p" | foo == "P") {    # if the user has typed "p" or "P"
        foo = readline(prompt = "Press enter when you want to resume the process")  # Offer a pause of indefinite length
   }
}

# Main
for (i in somelist){
    ...
    DoYouWantaPause()
}

#1 reason to read the docs before trying new things: `?R.utils::withTimeout: Furthermore, it is not possible to interrupt/break out of a "readline" prompt (e.g. readline() and readLines()) using timeouts; the timeout exception will not be thrown until after the user completes the prompt (i.e. after pressing ENTER).` — rawr, Dec 10 '14 at 21:14
Yes, I knew that made no sense but it was helpful to explain my needs. Thanks for the copy of the docs. — Remi.b, Dec 10 '14 at 21:29

score 10 · Accepted Answer · edited May 23 '17 at 11:51

Here is a quick little function based on the tcltk and tcltk2 packages:

library(tcltk)
library(tcltk2)

mywait <- function() {
    tt <- tktoplevel()
    tmp <- tclAfter(5000, function()tkdestroy(tt))
    tkpack( tkbutton(tt, text='Pause', command=function()tclAfterCancel(tmp)))
    tkpack( tkbutton(tt, text='Continue', command=function()tkdestroy(tt)),
        side='bottom')
    tkbind(tt,'<Key>', function()tkdestroy(tt) )

    tkwait.window(tt)
    invisible()
}

Run mywait and a small window will pop-up with 2 buttons, if you don't do anything then after about 5 seconds the window will go away and mywait will return allowing R to continue. If you click on "Continue" at any time then it will return immediately. If you click on "Pause" then the countdown will stop and it will wait for you to click on continue (or pressing an key) before continuing on.

This is an extension of the answer given here.

R: Offer 5 seconds to demand a pause. If no pause demanded, resume the process

1 Answers1