[R] Populate matrix from data.frame

From: Andrej Kastrin <andrej.kastrin_at_siol.net>
Date: Thu, 28 Jun 2007 08:22:18 +0200


Dear all,

I have a data frame
a <- data.frame(cbind(x=c('a','a','a','b','c'), y=c('a','b','c','d','e'),z=c(1,2,3,4,5)))
> a

  x y z
1 a a 1
2 a b 2
3 a c 3
4 b d 4
5 c e 5

and a matrix
mm <- matrix(0,5,5)
colnames(mm) <- c('a','b','c','d','e')
rownames(mm) <- c('a','b','c','d','e')

> mm

  a b c d e
a 0 0 0 0 0
b 0 0 0 0 0
c 0 0 0 0 0
d 0 0 0 0 0
e 0 0 0 0 0

How to populate matrix in a way that first column of data frame 'a' correspond to rownames(mm), second column to colnames(mm) and the third column is the element of matrix 'mm'?

Thanks in advance,
Andrej



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