Dear R users,
I'd like to compute "rho"(looks like a correlation matrix) with every two
columns of "uu" matrix below.
Toy example,
> uu <- matrix(1:15, nr=3, nc=5)
> uu
[,1] [,2] [,3] [,4] [,5]
[1,] 1 4 7 10 13
[2,] 2 5 8 11 14
[3,] 3 6 9 12 15
rho <- function(x,y)
{
sum(x*y)/(sqrt(sum(x^2))*sqrt(sum(y^2)))
}
rho_12 <- rho(uu[,1],uu[,2])
rho_13 <- rho(uu[,1],uu[,3])
rho_14 <- rho(uu[,1],uu[,4])
rho_15 <- rho(uu[,1],uu[,5])
rho_23 <- rho(uu[,2],uu[,3])
rho_24 <- rho(uu[,2],uu[,4])
rho_24 <- rho(uu[,2],uu[,5])
rho_34 <- rho(uu[,3],uu[,4])
rho_35 <- rho(uu[,3],uu[,5])
rho_45 <- rho(uu[,4],uu[,5])
Actually, the matrix uu is huge, 20*1000. Would you plz tell me how to
calculate "rho", more efficiently??
Any suggestion will be greatly appreciated.
Best,
Kathryn Lord
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