[R] Change in behavior of compare statement

From: Tomas Andersson <tomasan_at_gmail.com>
Date: Tue 20 Sep 2005 - 02:25:15 EST

Dear all,

I have come across some Windows Script code which calls the "file.exists" function in R to check for the existence of a particular file on an R server. This is what the code looks like:

                        // some useful code
            while (m_workspace.session.eval("file.exists(" + dataFile
+ ")") != "1");

It appears that the behavior of this code is different when used with R version 2.1.1 compared to R version 1.9.1. If the compare statement s is changed from

            while (s != "1")

            while (s != "True")

            while !(s)

the behavior of the code is the same with both versions of R.

After reading the R documentation, I have not found any evidence that the original syntax (s != "1") is in any way recommended or supported (in version 2.1.1). Still, my questions are:

  1. Is it possible that the syntax has been supported in older versions of R?
  2. Is the reason for the recent change in behavior known and documented anywhere?

I have been unable to find an answer to either question, so any information about this would be appreciated.


T. Andersson

R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Wed Sep 21 02:34:06 2005

This archive was generated by hypermail 2.1.8 : Fri 03 Mar 2006 - 03:40:16 EST