Let's make it a data frame instead: # Read the data from your post into a data frame named d: d <- read.table(textConnection(" 0.98 2 0.2 1 0.01 2 0.5 1 0.6 6")) closeAllConnections()
# Use the ave() function and append the result to d: d$sumprob <- with(d, ave(V1, V2, FUN = sum)) > d V1 V2 sumprob 1 0.98 2 0.99 2 0.20 1 0.70 3 0.01 2 0.99 4 0.50 1 0.70 5 0.60 6 0.60 HTH, Dennis On Sat, Oct 1, 2011 at 6:06 PM, Jim Silverton <jim.silver...@gmail.com> wrote: > Hi all, > I have 2 columns in a mtrix, one of which is a column of probabilities and > the other is simply a vector of integers. I want to sum all the > probabilities with the same integer value and put it in a new column. > For example, > If my matrix is: > > 0.98 2 > 0.2 1 > 0.01 2 > 0.5 1 > 0.6 6 > > > Then I should get: > 0.98 2 0.99 > 0.2 1 0.70 > 0.01 2 0.99 > 0.5 1 0.70 > 0.6 6 0.60 > > Any help is greatly appreciated. > > > > -- > Thanks, > Jim. > > [[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. > ______________________________________________ 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.