try this: > test <- data.frame(A=c("a", "a", "a", "b", "b", "c", "c", "c", "c"), > B=c(3,2,1,3,2,2,3,1,1)) > test A B 1 a 3 2 a 2 3 a 1 4 b 3 5 b 2 6 c 2 7 c 3 8 c 1 9 c 1 > # determine which group is not decreasing > tapply(test$B, test$A, function(x) any(diff(x) > 0)) a b c FALSE FALSE TRUE >
On Sun, Jun 19, 2011 at 4:20 PM, Christopher Peters <cpet...@lsu.edu> wrote: > I have a data.frame as follows: > > a 3 > a 2 > a 1 > b 3 > b 2 > c 2 > c 3 > c 1 > c 1 > > Each factor (a, b, c) should be monotonically decreasing, notice that factor > 'c' is not. > > I could use some help to figure out how to form a logical structure (mostly > just syntax), that will check each 'next value' for each factor to see if it > is less than the previous value. If it is less than the previous value, do > nothing, else subtract 'next value' from 'current value', add that amount to > the starting value and each previous value to the 'next value' is greater > than 'previous value'. > > So basically the data.frame would look like: > > a 3 > a 2 > a 1 > b 3 > b 2 > c 3 > c 3 > c 1 > c 1 > > Thanks for your help! > __________________________________ > Christopher P. Peters > Research Associate > Center for Energy Studies > http://www.enrg.lsu.edu/staff/peters > Energy, Coast & Environment Building > Louisiana State University > Baton Rouge, LA 70803 > Telephone: 225-578-4400 > Fax: 225-578-4541 > > [[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. > -- Jim Holtman Data Munger Guru What is the problem that you are trying to solve? ______________________________________________ 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.