On Tue, Apr 24, 2012 at 01:36:25PM -0700, Hans Thompson wrote:
> Hello, this forum was very helpful yesterday with a simple question I had on
> working with tables. What function will I need to use to do the following.
>
> Move matrix a:
>
> A B C D
> x 1 2 3 4
> y 5 6 7 8
>
> to the mean of B&C and C&D:
>
> BC CD
> x 2.5 3.5
> y 6.5 7.5
>
> and then to the mean of B&CB, C&BC, C&CD, and D&CD:
>
> AAB BAB CCD DCD
> x 1.75 2.25 3.25 3.75
> y 6.25 6.75 7.25 7.75
Hi.
Try the following.
# initial matrix
a <- matrix(1:8, nrow=2, byrow=TRUE)
dimnames(a) <- list(c("x","y"), LETTERS[1:4])
#create new matrix
b <- cbind(BC=(a[,"B"]+a[,"C"])/2, CD=(a[,"C"]+a[,"D"])/2)
b
BC CD
x 2.5 3.5
y 6.5 7.5
The next step may be done similarly using cbind(AAB=..., BAB=...).
Hope this helps.
Petr Savicky.
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