Hi: Another angle. Calling your example data frame df,
df <- transform(df, Rank = with(df, ave(value, level, FUN = rank))) df[with(df, order(level, value)), ] value level Rank 3 2 A 1 1 4 A 2 2 5 A 3 5 9 B 1 4 10 B 2 6 34 B 3 9 34 C 1 7 100 C 2 8 101 C 3 Note: If you try to use rank = blah instead of Rank = blah in transform(), an error will be thrown; another reason not to use the names of functions in the base package as variable names. Dennis On Fri, May 27, 2011 at 12:12 PM, xin wei <xin...@stat.psu.edu> wrote: > hello, I have the following data manipulation issue. the following is the > sample data: > > value level > 4 A > 5 A > 2 A > 10 B > 9 B > 34 B > 100 C > 34 C > 101 C. > > I hope to get the following result: > value level rank > 2 A 1 > 4 A 2 > 5 A 3 > 9 B 1 > 10 B 2 > 34 B 3 > 34 C 1 > 100 C 2 > 101 C. 3 > > as you may see, I need the data sorted and indexed within each level of > "level". what do I need to do calculate the rank variable? > > thanks, > > -- > View this message in context: > http://r.789695.n4.nabble.com/how-to-add-row-index-based-a-categorical-column-tp3556126p3556126.html > Sent from the R help mailing list archive at Nabble.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. > ______________________________________________ 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.
