Note that your example may be misleadingly simple, so I made it a bit more complicated.
The key is ?match > mylevels <- data.frame(ID=10:1,code=letters[1:10]) > values <- c(1,2,5,5,10) > with(mylevels,code[match(values,ID)]) [1] j i f f a Levels: a b c d e f g h i j ## Note that you may have to take care if there are NA's in values. Read ?match carefully if this might happen. Cheers, Bert > Bert Gunter Genentech Nonclinical Biostatistics (650) 467-7374 "Data is not information. Information is not knowledge. And knowledge is certainly not wisdom." H. Gilbert Welch On Fri, Mar 28, 2014 at 1:38 PM, Jonathan Greenberg <j...@illinois.edu> wrote: > R-helpers: > > Hopefully this is an easy one. Given a lookup table: > > mylevels <- data.frame(ID=1:10,code=letters[1:10]) > > And a set of values (note these do not completely cover the mylevels range): > > values <- c(1,2,5,5,10) > > How do I convert values to a factor object, using the mylevels to > define the correct levels (ID matches the values), and code is the > label? > > --j > > -- > Jonathan A. Greenberg, PhD > Assistant Professor > Global Environmental Analysis and Remote Sensing (GEARS) Laboratory > Department of Geography and Geographic Information Science > University of Illinois at Urbana-Champaign > 259 Computing Applications Building, MC-150 > 605 East Springfield Avenue > Champaign, IL 61820-6371 > Phone: 217-300-1924 > http://www.geog.illinois.edu/~jgrn/ > AIM: jgrn307, MSN: jgrn...@hotmail.com, Gchat: jgrn307, Skype: jgrn3007 > > ______________________________________________ > 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. ______________________________________________ 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.
