[R] User input when running R code in batch mode
Hi I've been stumbling over a simple issue that undoubtedly has an easy solution. I need to have some way for a user to enter some values into a data frame which R will then work on. I know that data entry should ideally be done otherwise and I should use R only for the computation, but R's data manipulation abilities makes it efficient for me to write the entire code in it. When I ran R line-by-line, I did: a - scan (what='character',n=1) 1: abcd Read 1 item a [1] abcd Everything works fine. But if I save the line a - scan (what='character', n=1); a as `test.r' and run the file in command line, I get: $ r --vanilla test.r a - scan(what='character',n=1); a 1: Read 0 items character(0) Now it's not working. I read what others had suggested on earlier threads and tried different functions, including readLines(). In line-by-line, I wrote the same lines as earlier, except using `readLines(con=stdin(),n=1)' instead of `scan(what='character', n=1)'. It worked fine. Yet, when I tried the modified lines (with readLines() instead of scan()) in batch mode, R didn't wait for user input and said `character(0)'. Is there any way to make R stop for the user to enter values when running in batch mode either by changing the way I invoke scan() or readLines() or by using any other function? Thanks in advance -- Kaushik Krishnan (kaushik.s.krish...@gmail.com) __ R-help@r-project.org mailing list 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.
Re: [R] User input when running R code in batch mode
On Tue, Oct 27, 2009 at 9:20 AM, Kaushik Krishnan kaushik.s.krish...@gmail.com wrote: $ r --vanilla test.r a - scan(what='character',n=1); a 1: Read 0 items character(0) Now it's not working. Assuming this is a unix environment, the syntax ' test.r' means 'my standard input stream is the file test.r'. That's not what you want. Give R the file name as an argument and let the standard input stream remain user input: $ r --vanilla test.r 1: hello Read 1 item [1] hello Note that this is 'r' and not 'R'. For me this comes from the 'littler' package in Ubuntu Linux. The same thing with 'R' doesn't work: $ R --vanilla test.r ARGUMENT 'test.r' __ignored__ [banner] [the R prompt appears] Maybe there's a way of doing this with big R, but I think littler is designed for this kind of thing. Is there any way to make R stop for the user to enter values when running in batch mode either by changing the way I invoke scan() or readLines() or by using any other function? An alternative is to use the tcltk package to make a dialog for user input. Barry __ R-help@r-project.org mailing list 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.
Re: [R] User input when running R code in batch mode
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Hash: SHA1
Kaushik Krishnan wrote:
Is there any way to make R stop for the user to enter values when
running in batch mode either by changing the way I invoke scan() or
readLines() or by using any other function?
At least on linux this works:
be...@t40:~/r-test $ cat test.R
readline2 = function(prompt=){
cat(prompt)
readLines(stdin, 1)
}
print(readline2(enter a number: ))
be...@t40:~/r-test $ Rscript test.R
enter a number: 42
[1] 42
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Re: [R] User input when running R code in batch mode
Barry Rowlingson b.rowling...@lancaster.ac.uk on Tue, 27 Oct 2009 10:17:24 +0100 writes: On Tue, Oct 27, 2009 at 9:20 AM, Kaushik Krishnan kaushik.s.krish...@gmail.com wrote: $ r --vanilla test.r a - scan(what='character',n=1); a 1: Read 0 items character(0) Now it's not working. Assuming this is a unix environment, the syntax ' test.r' means 'my standard input stream is the file test.r'. That's not what you want. Give R the file name as an argument and let the standard input stream remain user input: $ r --vanilla test.r 1: hello Read 1 item [1] hello Note that this is 'r' and not 'R'. For me this comes from the 'littler' package in Ubuntu Linux. The same thing with 'R' doesn't work: $ R --vanilla test.r ARGUMENT 'test.r' __ignored__ [banner] [the R prompt appears] Maybe there's a way of doing this with big R, but I think littler is designed for this kind of thing. yes, and it was historically the first, and maybe still the most efficient way to do so. The big R way is to use 'Rscript' which comes with R, e.g., Rscript --vanilla -e 'cat(a string please: ); a - readLines(stdin,n=1); str(a)' input a string please: Foobar chr Foobar (Note that here I use -e 'expression' instead of an R script file which of course is possible too). Martin Maechler, ETH Zurich Is there any way to make R stop for the user to enter values when running in batch mode either by changing the way I invoke scan() or readLines() or by using any other function? An alternative is to use the tcltk package to make a dialog for user input. Barry __ R-help@r-project.org mailing list 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. __ R-help@r-project.org mailing list 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.
