On Mar 19, 2010, at 4:11 PM, duncandonutz wrote:
I have two symmetric matrices, but of different dimensions. The
entries are
identified by specific labels some of which are shared by both
matrices. I
would like to sum the two matrices, but retain the union of the
two. In
other words, I want the result to be the same size as the larger of
the two
matrices, but with the entries that they share added together.
cbind() and rbind() don't work since the matrices are different sizes
(symmetrically). Merge doesn't want to cooperate, although it might
be
because I can't understand the documentation. I tried the package
"reshape"
but didn't get very far with that either. I tried simply adding (+)
them,
but that was a stupid first try.
See if this effort to construct an example and implement what it
sounds like you are asking is effective:
> A <- matrix(1:25, 5)
> B <- matrix(1:9, 3)
> colnames(A) <- c(letters[1:5])
> colnames(B) <- c(letters[1:3])
> rownames(B) <- c(letters[1:3])
> rownames(A) <- c(letters[1:5])
> rownames(A)[1] <- "A"
> intersect(rownames(A),rownames(B))
[1] "b" "c"
> intersect(colnames(A),colnames(B))
[1] "a" "b" "c"
>
A[intersect(rownames(A),rownames(B)),intersect(colnames(A),colnames(B))]
a b c
b 2 7 12
c 3 8 13
>
B[intersect(rownames(A),rownames(B)),intersect(colnames(A),colnames(B))]
a b c
b 2 5 8
c 3 6 9
>
A
[intersect
(rownames(A),rownames(B)),intersect(colnames(A),colnames(B))] <-
A
[intersect
(rownames(A),rownames(B)),intersect(colnames(A),colnames(B))] +
B[intersect(rownames(A),rownames(B)),intersect(colnames(A),colnames(B))]
> A
a b c d e
A 1 6 11 16 21
b 4 12 20 17 22
c 6 14 22 18 23
d 4 9 14 19 24
e 5 10 15 20 25
--
David
Any help is appreciated!
--
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