How to fix a while loop with multiple conditions returning an error

multiple-conditions, r, while-loop

Solution

You have the bones of what should be the general idea here, but you've been tripped up in several places by simple mistakes. Here's an annotated version that works as you describe:

yr_function <-function(){
   res <- as.numeric(readline("Is the year of concern 2012 or 2013? >>> "))
   if (is.na(res)){
    res <- -1
   }
   res
}

One of your first problems revolved around scope. You defined `year_of_data` both inside this function and just before your `while` loop. But the variable created inside the function will not refer to the one before the `while` loop. They exist in separate environments. So I modified this function to instead return the value that is input by the user.

You didn't discuss validation much, which is a big topic. I've added a very small bit of validation here. Basically, if the user enters something that can't be reasonably coerced to numeric, then you'll get an NA value, which will be a headache down the road. So I simply check for that and return -1 in that case. This is not a complete solution to the validation problem.

year_of_data <- 0
while((year_of_data != 2012) & (year_of_data != 2013)){
    year_of_data <- yr_function()
    if (!year_of_data %in% c(2012,2013)){
        print("You must type either 2012 or 2013")
    }else{
        break
    }
}

Here's the fixed `while` loop. First I fixed a few simple syntax errors (it's `while` not `While`, etc). Then I assigned the result of `yr_function()` to `year_of_data`, so that we can then check the resulting value and act accordingly.

Your attempt at the `if` condition (`year_of_data != (2012 | 2013)`) was not syntactically correct, so I switched to checking if the value was contained in the vector `c(2012,2013)`.

Lastly, you had followed the `if` with a comma and then a print statement. The comma is another syntax error. So I added braces around the `print` statement, and added an `else` clause that breaks out of the `while` loop if the user entered something correct.

More generally, you may want to investigate the function `menu` for this sort of task. It will probably make the validation issues a bit simpler to deal with.

Problem

Original source