Or even aggregate(DF[3:4], DF[1:2], sum)
On 2/24/06, Marc Schwartz (via MN) <[EMAIL PROTECTED]> wrote: > On Fri, 2006-02-24 at 08:18 -0800, Matt Crawford wrote: > > I am having trouble doing the following. I have a data.frame like > > this, where x and y are a variable that I want to do calculations on: > > > > Name Year x y > > ab 2001 15 3 > > ab 2001 10 2 > > ab 2002 12 8 > > ab 2003 7 10 > > dv 2002 10 15 > > dv 2002 3 2 > > dv 2003 1 15 > > > > Before I do all the other things I need to do with this data, I need > > to summarize or collapse the data by name and year. I've found that I > > can do things like > > nameyear<-interaction(name,year) > > dataframe$nameyear<-nameyear > > tapply(dataframe$x,dataframe$nameyear,sum) > > tapply(dataframe$y,dataframe$nameyear,sum) > > and then bind those together. > > > > But my problem is that I need to somehow retain the original Names in > > my collapsed dataset, so that later I can do analyses with the Name > > factors. All I can think of is something like > > tapply(dataframe$Name,dataframe$nameyear, somefunction?) > > but nothing seems to work. > > > > I'm actually trying to convert a SAS program, and I can't get out of > > that mindset. There, it's a simple Proc Means, By Name Year. > > > > Thanks for any help or suggestions on the right way to go about this. > > > > Matt Crawford > > Matt, > > Just use aggregate(): > > > aggregate(MyDF[, 3:4], list(Name = MyDF$Name, Year = MyDF$Year), sum) > Name Year x y > 1 ab 2001 25 5 > 2 ab 2002 12 8 > 3 dv 2002 13 17 > 4 ab 2003 7 10 > 5 dv 2003 1 15 > > > See ?aggregate for more information. > > HTH, > > Marc Schwartz > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html