In reshape2 this does the job: dcast(mydf,city~brand,sum)
On Wed, Nov 3, 2010 at 4:37 PM, Dimitri Liakhovitski <dimitri.liakhovit...@gmail.com> wrote: > Thanks a lot! > > Yes - I just found the reshape package too - and guess what, my math was > wrong! > reshape2 seems like the more up-to-date version of reshape. > > Wonder what's faster - xtabs or dcast... > Dimitri > > On Wed, Nov 3, 2010 at 4:32 PM, Henrique Dallazuanna <www...@gmail.com> wrote: >> Try this: >> >> xtabs(value ~ city + brand, mydf) >> >> On Wed, Nov 3, 2010 at 6:23 PM, Dimitri Liakhovitski >> <dimitri.liakhovit...@gmail.com> wrote: >>> >>> Hello! >>> >>> I have a data frame like this one: >>> >>> >>> mydf<-data.frame(city=c("a","a","a","a","a","a","a","a","b","b","b","b","b","b","b","b"), >>> brand=c("x","x","y","y","z","z","z","z","x","x","x","y","y","y","z","z"), >>> value=c(1,2,11,12,111,112,113,114,3,4,5,13,14,15,115,116)) >>> (mydf) >>> >>> What I need to get is a data frame like the one below - cities as >>> rows, brands as columns, and the sums of the "value" within each >>> city/brand combination in the body of the data frame: >>> >>> city x y z >>> a 3 23 336 >>> b 7 42 231 >>> >>> >>> I have written a code that involves multiple loops and subindexing - >>> but it's taking too long. >>> I am sure there must be a more efficient way of doing it. >>> >>> Thanks a lot for your hints! >>> >>> >>> -- >>> Dimitri Liakhovitski >>> Ninah Consulting >>> www.ninah.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. >> >> >> >> -- >> Henrique Dallazuanna >> Curitiba-Paraná-Brasil >> 25° 25' 40" S 49° 16' 22" O >> > > > > -- > Dimitri Liakhovitski > Ninah Consulting > www.ninah.com > -- Dimitri Liakhovitski Ninah Consulting www.ninah.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.