Hi Gary, Another possibility besides Erik's (although I suspect his is what you are really after):
## easier way to data z <- cbind(x = 1:10, y = 11:20) z[z[,"x"] == 5, "y"] - 1 ## To see what is "going on", break it into pieces ## logical; does column 'x' of 'z' equal 5? z[, "x"] == 5 ## all values in column 'y' z[ , "y"] ## subtract 1 from the values in column 'y' z[ , "y"] - 1 ## For documentation ?"[" ?Logic Cheers, Josh On Tue, Feb 22, 2011 at 9:18 AM, Hongwei Dong <pdxd...@gmail.com> wrote: > Hi, R users, > > I'm wondering if I can identify an element in a column by an element in > another column. For example: > > x<-1:10 > y<-11:20 > z<-cbind(x,y) > z > x y > [1,] 1 11 > [2,] 2 12 > [3,] 3 13 > [4,] 4 14 > [5,] 5 15 > [6,] 6 16 > [7,] 7 17 > [8,] 8 18 > [9,] 9 19 > [10,] 10 20 > > What I want to do is: when x=5, y=y-1 > > Anyone can tell me how to do this? Thanks. > > > Gary > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. > -- Joshua Wiley Ph.D. Student, Health Psychology University of California, Los Angeles http://www.joshuawiley.com/ ______________________________________________ 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.
