Hi, By comparing the different methods: set.seed(5) mat1<-matrix(sample(1:1e6,1e6,replace=TRUE),ncol=10000) set.seed(25) x<-sample(1:1e6,10000,replace=TRUE) system.time(z1<-sweep(-mat1,2,x,"+")) # user system elapsed # 0.076 0.000 0.069 system.time(z2<-apply(-mat1,1,`+`,x)) # user system elapsed # 0.036 0.000 0.031 system.time(z3<-aaply(-mat1,1,`+`,x)) # user system elapsed # 1.880 0.000 1.704 system.time(z4<- x-t(mat1)) #winner # user system elapsed # 0.004 0.000 0.007 system.time(z5<- t(x-t(mat1))) # user system elapsed # 0.008 0.000 0.009
A.K. ________________________________ From: C W <tmrs...@gmail.com> To: arun <smartpink...@yahoo.com> Cc: R help <r-help@r-project.org>; Sarah Goslee <sarah.gos...@gmail.com> Sent: Wednesday, December 5, 2012 4:11 PM Subject: Re: [R] data manipulation between vector and matrix thanks, I knew about apply, but did not you you can put plus signs with quotes. That's a cool tricky, Mike On Wed, Dec 5, 2012 at 4:05 PM, arun <smartpink...@yahoo.com> wrote: HI, >In addition to ?sweep(), you can use > >apply(-mat,1,`+`,x) > >#or >library(plyr) >aaply(-mat,1,"+",x) > > >A.K. > > > > > > > >----- Original Message ----- >From: C W <tmrs...@gmail.com> >To: Sarah Goslee <sarah.gos...@gmail.com> >Cc: r-help <r-help@r-project.org> >Sent: Wednesday, December 5, 2012 1:51 PM >Subject: Re: [R] data manipulation between vector and matrix > >Thanks, Sarah. First time heard about sweep(), it worked just the way I >wanted. >Mike > >On Wed, Dec 5, 2012 at 1:42 PM, Sarah Goslee <sarah.gos...@gmail.com> wrote: > >> Hi, >> >> On Wed, Dec 5, 2012 at 1:30 PM, C W <tmrs...@gmail.com> wrote: >> > Dear list, >> > I was curious how to subtract a vector from matrix? >> > >> > Say, I have >> > >> > mat <- matrix(1:40, nrow=20, ncol=2) >> > >> > x <-c(1,2) >> >> Thanks for the actual reproducible example. >> >> > I want, >> > >> > x-mat[1,] and x-mat[2,], and so on... Basically, subtract column elements >> > of x against column elements in mat. >> > >> > But x-mat won't do it. >> >> This will (note the modification to get x - mat): >> > sweep(-mat, 2, x, "+") >> [,1] [,2] >> [1,] 0 -19 >> [2,] -1 -20 >> [3,] -2 -21 >> [4,] -3 -22 >> [5,] -4 -23 >> etc. >> >> -- >> Sarah Goslee >> http://www.functionaldiversity.org >> > > [[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.
