# [R] Combine matrix

Gabor Grothendieck ggrothendieck at gmail.com
Fri Aug 17 05:18:57 CEST 2007

```Try this.  We convert to data frame placing the row names in column 1, do
the merge, remove column 1 and convert back to matrix:

# test input
a <- matrix(1:25, nrow = 5,
dimnames = list(letters[1:5], rep("A", 5)))
b <- matrix(1:40, nrow = 8,
dimnames = list(rep(letters[1:2], each = 4), rep("B", 5)))

# 1. process
to.DF <- function(x) data.frame(rn = row.names(x), x, row.names = 1:nrow(x))
out <- as.matrix(merge(to.DF(a), to.DF(b), by = 1)[,-1])
colnames(out) <- c(colnames(a), colnames(b))
out

# 2. same but merge is done using sqldf
# assume same a, b and to.DF as before

library(sqldf)
DFa <- to.DF(a)
DFb <- to.DF(b)
out <- as.matrix(sqldf("select * from DFa join DFb using(rn)")[-1])
colnames(out) <- c(colnames(a), colnames(b))
out

# 3. same but uses sqldf and proto (which sqldf automatically loads)
# assume same a, b and to.DF as before

library(sqldf)
out <- as.matrix(sqldf("select * from a join b using(rn)",
envir = proto(a = to.DF(a), b = to.DF(b)))[-1])
colnames(out) <- c(colnames(a), colnames(b))
out

On 8/16/07, Gianni Burgin <gianni.burgin at gmail.com> wrote:
> let say something like this
>
>
> >a=matrix(1:25, nrow=5)
>
> >rownames(a)=letters[1:5]
> > colnames(a)=rep("A", 5)
>
> > a
>  A  A  A  A  A
> a 1  6 11 16 21
> b 2  7 12 17 22
> c 3  8 13 18 23
> d 4  9 14 19 24
> e 5 10 15 20 25
>
> > b=matrix(1:40, nrow=8)
> > rownames(b)=c(rep("a",4),rep("b",4))
> > colnames(b)=rep("B", 5)
>
> > b
>  B  B  B  B  B
> a 1  9 17 25 33
> a 2 10 18 26 34
> a 3 11 19 27 35
> a 4 12 20 28 36
> b 5 13 21 29 37
> b 6 14 22 30 38
> b 7 15 23 31 39
> b 8 16 24 32 40
>
> as a results I wold like something like
>
>  A  A  A  A  A  B  B  B  B  B
> a 1  6 11 16 21  1  9 17 25 33
> a 1  6 11 16 21  2 10 18 26 34
> a 1  6 11 16 21  3 11 19 27 35
> a 1  6 11 16 21  4 12 20 28 36
> b 2  7 12 17 22  5 13 21 29 37
> b 2  7 12 17 22  6 14 22 30 38
> b 2  7 12 17 22  7 15 23 31 39
> b 2  7 12 17 22  8 16 24 32 40
>
>
> does it is clear? is there a function that automate this operation?
>
>
> thank you very much!
>
>
>
>
> On 8/16/07, jim holtman <jholtman at gmail.com> wrote:
> >
> > Can you provide an example of what you mean; e.g., the two input
> > matrices and the desired output.
> >
> > On 8/16/07, Gianni Burgin <gianni.burgin at gmail.com> wrote:
> > > Hi R user,
> > >
> > > I am new to R, and I have a very simple question for you. I have two
> > matrix
> > > A and B, with internally redundant rownames (but variables are
> > different).
> > > Some, but not all the rownames are shared among the two matrix. I want
> > to
> > > create a greater matrix that combines the previuos two, and has all the
> > > possible combinations of matching rownames lines among matrix A and B.
> > >
> > > looking for the solution I bumped in merge but actually works on
> > data.frame,
> > > and in dataframe there could be no redundancy in names.
> > >
> > >
> > > can you help me??
> > >
> > >        [[alternative HTML version deleted]]
> > >
> > > ______________________________________________
> > > R-help at stat.math.ethz.ch mailing list
> > > https://stat.ethz.ch/mailman/listinfo/r-help
> > http://www.R-project.org/posting-guide.html
> > > and provide commented, minimal, self-contained, reproducible code.
> > >
> >
> >
> > --
> > Jim Holtman
> > Cincinnati, OH
> > +1 513 646 9390
> >
> > What is the problem you are trying to solve?
> >
>
>        [[alternative HTML version deleted]]
>
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