try:
> a = c(1, 4, 5)
> b = c(2, 6, 7)
>
> m <- matrix(1:49,7,7)
> m[cbind(a,b)] # 'array' indexing
[1] 8 39 47
> m
[,1] [,2] [,3] [,4] [,5] [,6] [,7]
[1,] 1 8 15 22 29 36 43
[2,] 2 9 16 23 30 37 44
[3,] 3 10 17 24 31 38 45
[4,] 4 11 18 25 32 39 46
[5,] 5 12 19 26 33 40 47
[6,] 6 13 20 27 34 41 48
[7,] 7 14 21 28 35 42 49
>
Jim Holtman
"What is the problem you are trying to solve?"
----- Original Message ----
From: yoooooo <[EMAIL PROTECTED]>
To: [email protected]
Sent: Thursday, March 1, 2007 4:28:02 PM
Subject: [R] Simplest question ever...
Let's say i have
a = c(1, 4, 5)
b = c(2, 6, 7)
and i have matrix m, what's an efficient way of access
m[1, 2], m[4, 6], m[5, 7]
like of course m[a, b] = is not going to do, but what's an expression that
will allow me to have that list?
Thanks!
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