[R-sig-eco] Combining two matrices

[Peter Solymos]

Thiago,

It's all about indexing:

rn <- union(rownames(matrix1), rownames(matrix2))
cn <- union(colnames(matrix1), colnames(matrix2))
x <- array(0, dim=c(length(rn), length(cn)), dimnames=list(rn, cn))
x[rownames(matrix1), colnames(matrix1)] <- matrix1
x[rownames(matrix2), colnames(matrix2)] <- matrix2
x

Cheers,

Peter

--
Péter Sólymos, Dept Biol Sci, Univ Alberta, T6G 2E9, Canada AB
solymos at ualberta.ca, Ph 780.492.8534, http://psolymos.github.com
Alberta Biodiversity Monitoring Institute, http://www.abmi.ca
Boreal Avian Modelling Project, http://www.borealbirds.ca


On Sun, May 13, 2012 at 8:50 PM, Thiago Gonçalves-Souza
<tgoncalves.souza at gmail.com> wrote:
> Dear all,
>
> I have two species-by-site matrices and I'd like to combine them in one
> matrix. The rows (n=20) of each matrix present plants 1-20. So, the new
> matrix should have 40 rows. As these matrices have some shared species and
> some exclusive species, the new matrix should have the species from the two
> matrix, but when certain species that doesn't occur for example in Matrix
> 1, its value will be 0. I've tried the functions merge, cbind and rbind but
> I wasn't able to do it. Please, see the following example to make it clear
> ;-)
>
>
> By using for example the following matrices:
>
> matrix1 <- matrix(c(1,2,3, 11,12,13), nrow = 2, ncol=3, byrow=TRUE,
>               dimnames = list(c("plant1", "plant2"),
>                               c("sp1", "sp2", "sp3")))
>
> matrix2 <- matrix(c(1,2,3, 0,21,9), nrow = 2, ncol=3, byrow=TRUE,
>               dimnames = list(c("plant3", "plant4"),
>                               c("sp1", "sp2", "sp4")))
>
> I'd like to combine them  like this:
>
> new.matrix <- matrix(c(1, 2, 3, 0, 11, 12, 13, 0, 1, 2, 0, 3, 0,21,0,9),
>              nrow = 4, ncol=4, byrow=TRUE,
>               dimnames = list(c("plant1", "plant2", "plant3", "plant4"),
>                               c("sp1", "sp2", "sp3", "sp4")))
>
> Once I have 200 columns and 80 rows, I'm pretty sure that R can help me to
> do it automatically ;-)
>
>
> All the best,
> Thiago.
>
>
> --
> Thiago Gonçalves-Souza, Ms.
> Universidade Estadual Paulista (UNESP)
> Departamento de Zoologia e Botânica
> Programa de Pós-Graduação em Biologia Animal (Doutorado)
> E-mail alternativo: thiagoaracno at gmail.com
> Home page:<http://www.wix.com/thiagocalvesouza/tg-s>
>
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>
>
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