[R] Pause script at input from terminal (interactive use)

[Bernard Comcast]

I have used the shiny package to create a web page user interface and it works well.

Bernard
Sent from my iPhone so please excuse the spelling!"

> On Apr 19, 2019, at 1:12 AM, Luigi Marongiu <marongiu.luigi using gmail.com> wrote:
> 
> I am realizing as well that R is not the best option for an
> interactive session. I changed the script to get the input from a
> config file; it is less elegant because the procedure now requires
> double the files than with CLI input, but at the end of the day is
> more practical when most of the answer remains the same between
> sessions. Thanks.
> 
>> On Thu, Apr 18, 2019 at 8:47 PM Greg Snow <538280 using gmail.com> wrote:
>> 
>> I am not an expert on Rscript, but I don't think that an actual
>> terminal is ever used when using Rscript.  And `interactive()` will
>> probably always be false.
>> 
>> So if you want the script to pause for input, you need to have some
>> form of user interface to work with.
>> 
>> One option is to use the tcltk package (this works on all OS's to my
>> knowledge, but not if you are accessing the computer remotely).  This
>> answer on stack overflow shows some code that may help:
>> https://stackoverflow.com/questions/16847621/get-data-out-of-a-tcltk-function/16847918#16847918
>> 
>> 
>>> On Thu, Apr 18, 2019 at 8:11 AM Luigi Marongiu <marongiu.luigi using gmail.com> wrote:
>>> 
>>> Dear all,
>>> I am trying to write an interactive script where the user type some
>>> input from the terminal. I used readline() but when I launch the file
>>> with Rscript, the function is overwritten directly, there is no
>>> waiting for the user's input. For instance, this example:
>>> 
>>> VAR1 = as.numeric(readline(prompt = "Enter something -> "))
>>> VAR2 = as.numeric(readline(prompt = "Enter something else -> "))
>>> if(is.na(VAR1)) VAR1 = 0
>>> if(is.na(VAR2)) VAR2 = "empty"
>>> cat("Input was: ", VAR1, " - ", VAR2, "\n")
>>> 
>>> is executed till the end without typing anything on terminal :
>>> 
>>> $ Rscript test.R
>>> Enter something ->
>>> Enter something else ->
>>> Input was:  0  -  empty
>>> 
>>> I also tried with ',1' at the end of readline, but the effect is the
>>> same. I should use the interactive() function but I am confused on its
>>> use.
>>> It is possible to launch R scritps in the interactive mode in the
>>> first place? and if yes, how? Or would python or julia be better
>>> choices in this case?
>>> Thank you.
>>> --
>>> Best regards,
>>> Luigi
>>> 
>>> ______________________________________________
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>>> and provide commented, minimal, self-contained, reproducible code.
>> 
>> 
>> 
>> --
>> Gregory (Greg) L. Snow Ph.D.
>> 538280 using gmail.com
> 
> 
> 
> -- 
> Best regards,
> Luigi
> 
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.