Make readline wait for input in R

Question

I am trying to have my code ask me the meaning of TRUE or FALSE before continuing.

Currently, it works fine if I run it one line at a time, however, when I run all the code at once in RStudio, it just continues without waiting for user input and writing the value "" for my parameter.

raw <- readline("TRUE or FALSE -- this is a validation run: ") if (raw == "F" | raw == "FALSE" | raw == "False"){ validation <- F } else{ validation <- T } rm(raw) 

Ideally, I need an answer that works no matter how I run it - RScript , source in RStudio or run it (i.e. select the code and press run or ctrl-enter).

Answer 1

If you want to do this interactively, you already have answers, but not for use with Rscript. To do this, you need to send messages to the console using cat :

If this test file is named "prompt.r" and is located in the directory where you are working in the system console session:

 cat("a string please: "); a <- readLines("stdin",n=1); cat("You entered") str(a); cat( "\n" ) 

Then you can run it from the command line as

 $ Rscript prompt.r 

If you need a universal script, then it will run your script in interactive conditions and my script for non-interactive:

 if (interactive() ){raw <- readline("TRUE or FALSE -- this is a validation run: ") if (raw == "F" | raw == "FALSE" | raw == "False"){ validation <- F } else{ validation <- T } rm(raw) } else{ # non-interactive cat("a string please: "); a <- readLines("stdin",n=1); cat("You entered") str(a); cat( "\n" )} 

Answer 2

Do you execute code by highlighting lines and clicking the "Run" button? If so, this may be your problem, because R is in turn entering your code in the terminal.

Instead, write a script (or comment out the parts that you are not testing) and click the source button. R then waits for the user's response instead of entering a line after readline () in readline ().

I had the same problem as you, which prompted me to look for an answer. But then I tried this other code execution method and it worked.