Another option is apply(X,2,function(x) x-mean(x))
Hope this is helpful, Dan Daniel Nordlund, PhD Research and Data Analysis Division Services & Enterprise Support Administration Washington State Department of Social and Health Services -----Original Message----- From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of Sarah Goslee Sent: Monday, September 14, 2015 10:07 AM To: JORGE COLACO Cc: r-help Subject: Re: [R] R WRONG CALCULATIONS - Please Help On Mon, Sep 14, 2015 at 11:11 AM, JORGE COLACO <j_col...@utad.pt> wrote: > I would greatly appreciate if you could let me know why the R does not > make the right computations in the case below. > Waiting for your reply > Jorge Colaço R made the correct computations: it did exactly what you told it. It isn't R's fault that what you told it isn't what you meant. You want to subtract the column means from each column; what you actual told R was to subtract Xmean from X element by element column-wise, recycling Xmean as necessary. Here's what you meant: X<-matrix(c(-1,0,1,-1,1,0, 0,0,1,1,1,-1, -1,0,-1,1,0,1, 1,1,-1,-1,0,0, 0,0,1,1,-1,1),nrow=5,ncol=6,byrow=T) Xmean <- colMeans(X) sweep(X, 2, Xmean, "-") Thank you for providing a simple reproducible example and clear idea of what you intended. It made answering your question very straightforward. > > R version 3.2.2 (2015-08-14) -- "Fire Safety" > Copyright (C) 2015 The R Foundation for Statistical Computing > Platform: i386-w64-mingw32/i386 (32-bit) > > R is free software and comes with ABSOLUTELY NO WARRANTY. > You are welcome to redistribute it under certain conditions. > Type 'license()' or 'licence()' for distribution details. > > R is a collaborative project with many contributors. > Type 'contributors()' for more information and 'citation()' on how to > cite R or R packages in publications. > > Type 'demo()' for some demos, 'help()' for on-line help, or > 'help.start()' for an HTML browser interface to help. > Type 'q()' to quit R. >> X<-matrix(c(-1,0,1,-1,1,0, > + 0,0,1,1,1,-1, > + -1,0,-1,1,0,1, > + 1,1,-1,-1,0,0, > + 0,0,1,1,-1,1),nrow=5,ncol=6,byrow=T) > >> > mean<-c(mean(X[,1]),mean(X[,2]),mean(X[,3]),mean(X[,4]),mean(X[,5]),me > an(X[,6])) >> mean > [1] -0.2 0.2 0.2 0.2 0.2 0.2 >> X-mean > [,1] [,2] [,3] [,4] [,5] [,6] > [1,] -0.8 -0.2 0.8 -1.2 0.8 -0.2 > [2,] -0.2 0.2 0.8 0.8 0.8 -1.2 > [3,] -1.2 -0.2 -0.8 0.8 -0.2 0.8 > [4,] 0.8 0.8 -1.2 -0.8 -0.2 -0.2 > [5,] -0.2 -0.2 0.8 0.8 -0.8 0.8 >> > > Right Result Should Be: > > ans = > -0.80000 -0.20000 0.80000 -1.20000 0.80000 -0.20000 > 0.20000 -0.20000 0.80000 0.80000 0.80000 -1.20000 > -0.80000 -0.20000 -1.20000 0.80000 -0.20000 0.80000 > 1.20000 0.80000 -1.20000 -1.20000 -0.20000 -0.20000 > 0.20000 -0.20000 0.80000 0.80000 -1.20000 0.80000 > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. -- Sarah Goslee http://www.functionaldiversity.org ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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 -- To UNSUBSCRIBE and more, see 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.
