HI Andras, No problem. But, i guess using colMeans() as suggested by Rainer should be faster in large datasets.
A.K. ----- Original Message ----- From: Andras Farkas <motyoc...@yahoo.com> To: smartpink...@yahoo.com Cc: Sent: Sunday, September 2, 2012 4:59 PM Subject: Re: [R] Help on finding specific columns in matrix this works nicely, thanks arun... Andras ------------------------------ On Sun, Sep 2, 2012 11:50 AM EDT arun wrote: >Hi, >Try this: > which.min(apply(a,2,mean)) >#[1] 1 > which.max(apply(a,2,mean)) >#[1] 4 >A.K. > > > > >----- Original Message ----- >From: Andras Farkas <motyoc...@yahoo.com> >To: "r-help@r-project.org" <r-help@r-project.org> >Cc: >Sent: Sunday, September 2, 2012 5:49 AM >Subject: [R] Help on finding specific columns in matrix > >Dear All, > >I have a matrix with 33 columns and 5000 rows. I would like to find 2 specific >columns in the set: the one that holds the highest values and the one that >holds the lowest values. In this case the column's mean would be apropriate to >use to try to find those specific columns because each columns mean is >different and they all change together based on the same "change of rate >constants" as a function of time (ie: tme is the most important determinant of >the magnitude of that mean). The columns are not to be named, if possible.... >Any thoughts on that? Would apreciate the help.... > >example: > >a ><-matrix(c(runif(500,10,15),runif(500,15,20),runif(500,20,25),runif(500,25,30)),ncol=4) > >I would need to find and plot with a box percentile plot column 1, the column >with the lowest mean, and column 4, the column with the highest mean > >thanks, > >Andras > [[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.
