Greg Snow wrote: > Look carefully at the output and commands below. > > The first level of porosity is "macro " (notice the space at the > end) but you are asking for "macro" (without the space). Computers are > very literal, so "macro " is not equal to "macro". T
Greg and Chuck, Thanks for your very generous help. As Greg perceptively noted above, there is indeed a space after "macro ". When I went back and changed porosity == "macro" to "macro " the program ran without a flaw. I think this error goes back to the .csv file which I read into R. For some reason it's propagating a space after macro that's not visible in the file, but R picks up. In future, I'll be careful to note how R expresses variables read from external files. Sincerely, Robert Walters ______________________________________________ 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.