Dear Arun

Thank you for the very useful help.
However, please kindly explain the code below.
row.names(mat1)<- gsub("[_]"," ",row.names(mat1))

1. what does "[_]" mean?
2. what does " "  mean?
3. what does row.names(mat1) mean?

I checked ?gsub but still did not get the idea.

Thank you again

Elaine


On Wed, Jul 31, 2013 at 9:35 PM, arun <smartpink111@yahoo.com> wrote:

> HI,
>
> Please use ?dput()
> mat1<- as.matrix(read.table(text="
> D0989  D9820  D5629  D4327  D2134
> GID_1    1        0        0      1      0
> GID_2    0        1        1      0      0
> GID_4    0        0        1      0      0
> GID_5    1        1        0      0      0
> GID_7    0        1        0      0      1
> ",sep="",header=TRUE))
> row.names(mat1)<- gsub("[_]"," ",row.names(mat1))
> IslandA<-c("GID 1", "GID 5")
> IslandB<- c("GID 2", "GID 4", "GID 7")
>  res<-  t(sapply(c("IslandA","IslandB"),function(x)
> {x1<-mat1[match(get(x),row.names(mat1)),];(!!colSums(x1))*1} ))
>
>  res
> #        D0989 D9820 D5629 D4327 D2134
> #IslandA     1     1     0     1     0
> #IslandB     0     1     1     0     1
> A.K.
>
>
>
>
> ----- Original Message -----
> From: Elaine Kuo <elaine.kuo.tw@gmail.com>
> To: "r-help@stat.math.ethz.ch" <r-help@stat.math.ethz.ch>
> Cc:
> Sent: Wednesday, July 31, 2013 9:03 AM
> Subject: [R] merge matrix row data
>
> Dear list,
>
>
>
> I have a matrix showing the species presence-absence on a map.
>
> Its rows are map locations, represented by GridCellID, such as GID1 and GID
> 5.
>
> Its columns are species ID, such as D0989, D9820, and D5629.
>
> The matrix is as followed.
>
>
>
> Now I want to merge the GridCellID according to the map location of each
> island.
>
> For instance, Island A consist of GID 1 and 5. Island B consist of GID 2,
> 4, and 7.
>
> In GID 1 and 5, species D0989 are both 1.
>
> Then I want to merge GID 1 and 5 into Island A, with species D0989 as 1.
>
> The original matrix and the resulting matrix are listed below.
>
> Please kindly advise how to code the calculation in R.
>
> Please do not hesitate to ask if anything is unclear.
>
> Thank you in advance.
>
>
>
> Elaine
>
>
>
> Original matrix
>
>         D0989   D9820  D5629  D4327  D2134
>
> GID 1    1        0        0       1      0
>
> GID 2    0        1        1       0      0
>
> GID 4    0        0        1       0      0
>
> GID 5    1        1        0       0      0
>
> GID 7    0        1        0       0      1
>
>
>
> Resulting matrix
>
>                 D0989   D9820  D5629  D4327  D2134
>
> Island A   1        1       0       1       0
>
> Island B   0        1       1       0       1
>
>     [[alternative HTML version deleted]]
>
> ______________________________________________
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> 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.
>
>

	[[alternative HTML version deleted]]

