[R] How to get minimum value by group
I'd like to get a long data set of minimum values from groups in another data set. The following almost does what I want. (Note, I'm using the word factor differently from it's meaning in R; bad choice of words) myframe = data.frame(factor1 = rep(1:2,each=8), factor2 = rep(c(a,b),each=4, times=2), factor3 = rep(c(x,y),each=2, times=4), y=1:16) attach(myframe) minimums = by(y, list(factor1, factor2,factor3), min) detach(myframe) The problem is that minimums is object of class by, which looks like some kind of array with the number of dimension equal to the number of factors. I just want two dimensions though, with factors in columns. I can't figure out how to reformat it to something like this: factor1 factor2 factor2 y 1 a x 1 2 a x 9 1 b x 5 ... I could make nested for loops, but I'd like something that will work for an arbitrary number of factors. I've seen some functions that will rearrange data (e.g. reshape), but they all seem to require a data.frame to start with. -- View this message in context: http://n4.nabble.com/How-to-get-minimum-value-by-group-tp1011745p1011745.html Sent from the R help mailing list archive at Nabble.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.
Re: [R] How to get minimum value by group
On Jan 11, 2010, at 7:58 PM, JustinNabble wrote: I'd like to get a long data set of minimum values from groups in another data set. The following almost does what I want. (Note, I'm using the word factor differently from it's meaning in R; bad choice of words) myframe = data.frame(factor1 = rep(1:2,each=8), factor2 = rep(c(a,b),each=4, times=2), factor3 = rep(c(x,y),each=2, times=4), y=1:16) attach(myframe) # with(myframe, ) would be a better construction minimums = by(y, list(factor1, factor2,factor3), min) detach(myframe) It's a table, which IS like an array, You want: as.data.frame.table(minimums) Var1 Var2 Var3 Freq 11ax1 22ax9 31bx5 42bx 13 51ay3 62ay 11 71by7 82by 15 The problem is that minimums is object of class by, which looks like some kind of array with the number of dimension equal to the number of factors. I just want two dimensions though, with factors in columns. I can't figure out how to reformat it to something like this: factor1 factor2 factor2 y 1 a x 1 2 a x 9 1 b x 5 ... I could make nested for loops, but I'd like something that will work for an arbitrary number of factors. I've seen some functions that will rearrange data (e.g. reshape), but they all seem to require a data.frame to start with. -- -- David Winsemius, MD Heritage Laboratories West Hartford, CT __ 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.
Re: [R] How to get minimum value by group
Tena koe Justin Try aggregate(): e.g., aggregate(myframe[,4], myframe[,1:3], min) HTH Peter Alspach -Original Message- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of JustinNabble Sent: Tuesday, 12 January 2010 1:58 p.m. To: r-help@r-project.org Subject: [R] How to get minimum value by group I'd like to get a long data set of minimum values from groups in another data set. The following almost does what I want. (Note, I'm using the word factor differently from it's meaning in R; bad choice of words) myframe = data.frame(factor1 = rep(1:2,each=8), factor2 = rep(c(a,b),each=4, times=2), factor3 = rep(c(x,y),each=2, times=4), y=1:16) attach(myframe) minimums = by(y, list(factor1, factor2,factor3), min) detach(myframe) The problem is that minimums is object of class by, which looks like some kind of array with the number of dimension equal to the number of factors. I just want two dimensions though, with factors in columns. I can't figure out how to reformat it to something like this: factor1 factor2 factor2 y 1 a x 1 2 a x 9 1 b x 5 ... I could make nested for loops, but I'd like something that will work for an arbitrary number of factors. I've seen some functions that will rearrange data (e.g. reshape), but they all seem to require a data.frame to start with. -- View this message in context: http://n4.nabble.com/How-to-get-minimum-value-by-group-tp10117 45p1011745.html Sent from the R help mailing list archive at Nabble.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. __ 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.
Re: [R] How to get minimum value by group
Try this: aggregate(myframe[4], myframe[1:3], min) factor1 factor2 factor3 y 1 1 a x 1 2 2 a x 9 3 1 b x 5 4 2 b x 13 5 1 a y 3 6 2 a y 11 7 1 b y 7 8 2 b y 15 On Mon, Jan 11, 2010 at 7:58 PM, JustinNabble justinmmcgr...@hotmail.com wrote: I'd like to get a long data set of minimum values from groups in another data set. The following almost does what I want. (Note, I'm using the word factor differently from it's meaning in R; bad choice of words) myframe = data.frame(factor1 = rep(1:2,each=8), factor2 = rep(c(a,b),each=4, times=2), factor3 = rep(c(x,y),each=2, times=4), y=1:16) attach(myframe) minimums = by(y, list(factor1, factor2,factor3), min) detach(myframe) The problem is that minimums is object of class by, which looks like some kind of array with the number of dimension equal to the number of factors. I just want two dimensions though, with factors in columns. I can't figure out how to reformat it to something like this: factor1 factor2 factor2 y 1 a x 1 2 a x 9 1 b x 5 ... I could make nested for loops, but I'd like something that will work for an arbitrary number of factors. I've seen some functions that will rearrange data (e.g. reshape), but they all seem to require a data.frame to start with. -- View this message in context: http://n4.nabble.com/How-to-get-minimum-value-by-group-tp1011745p1011745.html Sent from the R help mailing list archive at Nabble.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. __ 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.
