I really want to do this: abline( a=tan(-kT*pi/180), b=kY-tan(-kT*pi/180)*kX )
where kX,kY and kT are vectors of equal length. But I can't do that with abline unless I use a loop, and I haven't figured out the least unelegant way of writing the loop yet. So is there a way to do this without a loop? Or if I am to resort to the loop, what's the best way of doing it considering that I have some missing data? Here's the mess that I wrote. converge <- na.omit(data.frame(kX,kY,kT)) for (z in (length(converge$kT))) {abline( a=tan(converge$kT[z]*pi/180), b=converge$kY[z]-tan(-converge$kT[z]*converge$kX[z]*pi/180) )} I think the missing data are causing the problem; this happens when I run: Error in int_abline(a = a, b = b, h = h, v = v, untf = untf, ...) : 'a' and 'b' must be finite ______________________________________________ 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.