Message-ID: <017a01cdfa79$ad114770$0733d650$@edu>
Date: 2013-01-24T21:27:56Z
From: David L Carlson
Subject: Question on matrix calculation
In-Reply-To: <1359059239.64805.YahooMailNeo@web142602.mail.bf1.yahoo.com>
Or just use aggregate()
# Redefine match_df to match your data.frame
> match_df <- data.frame(Seq = 1:5, criteria = letters[c(3, 5, 3, 3, 4)])
> aggregate(mat, list(match_df$criteria), sum)
Group.1 V1 V2 V3
1 a 7 17 27
2 c 2 7 12
3 d 6 16 26
# If you really want a matrix:
> as.matrix(aggregate(mat, list(match_df$criteria), sum)[,2:4])
V1 V2 V3
[1,] 8 23 38
[2,] 5 10 15
[3,] 2 7 12
----------------------------------------------
David L Carlson
Associate Professor of Anthropology
Texas A&M University
College Station, TX 77843-4352
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of arun
> Sent: Thursday, January 24, 2013 2:27 PM
> To: Christofer Bogaso
> Cc: R help
> Subject: Re: [R] Question on matrix calculation
>
> Hi,
>
> You could also use:
> mat <- matrix(1:15, 5)
> set.seed(5)
> match_df <- data.frame(Seq = 1:5, criteria = sample(letters[1:5], 5,
> replace = T),stringsAsFactors=F)
> library(plyr)
> res<-daply(as.data.frame(mat),.(match_df$criteria),colSums)
> res
>
> #match_df$criteria V1 V2 V3
> ? # ???????????? a? 5 10 15
> ?? # ??????????? b? 5 15 25
> ??? # ?????????? d? 2? 7 12
> ????? # ???????? e? 3? 8 13
>
>
> A.K.
>
>
>
> ----- Original Message -----
> From: Christofer Bogaso <bogaso.christofer at gmail.com>
> To: r-help <r-help at r-project.org>
> Cc:
> Sent: Thursday, January 24, 2013 2:39 PM
> Subject: [R] Question on matrix calculation
>
> Hello again,
>
> Ley say I have 1 matrix and 1 data frame:
>
> > mat <- matrix(1:15, 5)
> > match_df <- data.frame(Seq = 1:5, criteria = sample(letters[1:5], 5,
> replace = T))
> > mat
> ? ? [,1] [,2] [,3]
> [1,]? ? 1? ? 6? 11
> [2,]? ? 2? ? 7? 12
> [3,]? ? 3? ? 8? 13
> [4,]? ? 4? ? 9? 14
> [5,]? ? 5? 10? 15
> > match_df
> ? Seq criteria
> 1? 1? ? ? ? c
> 2? 2? ? ? ? e
> 3? 3? ? ? ? c
> 4? 4? ? ? ? c
> 5? 5? ? ? ? d
>
> Now I want to get the column-sums of 'mat' based on the unique
> elements of match_df[,'criteria']
>
> Therefore based on the 'match_df', my resulting matrix will have 3
> rows (because the unique elements here are 'c, e, & d'). And.........
>
> 1st row will be column sums for mat[c(1,3,4), ]
> 2nd row will be column sums for mat[c(2), ]
> 3rd row will be column sums for mat[c(5), ]
>
> I want to get a general framework, so that I can implement that in
> some big arbitrary matrix.
>
> Can somebody give me some pointer?
>
> Thanks and regards,
>
> ______________________________________________
> R-help at r-project.org mailing list
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>
> ______________________________________________
> R-help at 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.