On Sun, Nov 16, 2008 at 8:12 PM, jeffc <[EMAIL PROTECTED]> wrote: > > Hi, > > I have a data set similar to the following > > State Gender Quantity > TX Male 1 > NY Female 2 > TX Male 3 > NY Female 4 > > > I need to calculate cumulative sum of the quantity by State and Gender. The > expected output is > State Gender Quantity CumQuantity > TX Male 1 1 > TX Male 3 4 > NY Female 2 2 > NY Female 4 6 > > I highly appreciate if someone can give me some hints on solving that in R.
Here's one approach that uses the plyr package: library(plyr) ddply(df, .(State, Gender), transform, CumQuantity = cumsum(Quantity)) You can find out more about how this works at http://had.co.nz/plyr Hadley -- http://had.co.nz/ ______________________________________________ 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.
