If the seq(5,205) was a typo, and should have been
seq(5,20,5), then what you're looking for is the outer
product of x and y:
x = seq(5,20,5)
y = seq(5,20,5)
x %o% y
[,1] [,2] [,3] [,4]
[1,] 25 50 75 100
[2,] 50 100 150 200
[3,] 75 150 225 300
[4,] 100 200 300 400
outer(x,y)
[,1] [,2] [,3] [,4]
[1,] 25 50 75 100
[2,] 50 100 150 200
[3,] 75 150 225 300
[4,] 100 200 300 400
The outer() function will accepts a FUN= argument
which defaults to '*'.
- Phil Spector
Statistical Computing Facility
Department of Statistics
UC Berkeley
spec...@stat.berkeley.edu
On Sat, 5 Feb 2011, Mariana Martinez-Morales wrote:
Hi guys:
Sorry if this question is very basic. I’m learning basic matrix and
vectors multiplication to develop a population matrix model for
plants. I’m trying to multiply the elements of two vectors (each of
the “x” values by each of the “y” values) to obtain a square matrix of
xy values.
f.e.
x<-seq(5,205)
y<-seq(5,20,5)
stages<-c(“Sdl”, “Juv”, “Ad1”, “Ad2”)
If I just multiply xy as a matrix
xy<-matrix(x,y,nrow=4,ncol=4,dimnames=list(stages,stages))
I obtain this
xy
Sdl Juv A1 A2
Sdl 5 10 15 20
Juv 5 10 15 20
A1 5 10 15 20
A2 5 10 15 20
but what I want to obtain is this matrix
Sdl Juv A1 A2
Sdl 25 50 75 100
Juv 50 100 150 200
A1 75 50 225 300
A2 100 200 300 400
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
