Ian Coe wrote:
Hi,
Is there a way to convert a matrix into a vector representing all
permutations of values and column/row headings with native R functions?
I did this with 2 nested for loops and it took about 25 minutes to run
on a ~700x700 matrix. I'm assuming there must be a smarter way to do
this with R's vector commands, but being new to R, I'm having trouble
making it work.
Thanks,
Ian
[a] [b] [c]
[d] 1 4 7
[e] 2 5 8
[f] 3 6 9
a d 1
a e 2
a f 3
b d 4
b e 5
b f 6
c d 7
c e 8
c f 9
Ian Coe
Connective Capital Management, LLC
385 Homer Ave.
Palo Alto, CA 94301
(650) 321-4826 ext. 03
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Hi Ian,
Here's one way you could do it (assuming ori.mat is the original matrix
and ori.mat has labeled columns and rows):
a.matrix <- expand.grid(rownames(ori.mat),colnames(ori.mat))
final.answer <- cbind(a.matrix,ori.mat[seq_along(ori.mat)])
Cheers,
--
*Luc Villandré*
/Biostatistician
McGill University Health Center -
Montreal Children's Hospital Research Institute/
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