Comparing and counting sign of elements in two matrics

[sak]

I have two giant matrices (5000x6000) each. I want to compare the sign of elements of two matrices without doing a for loop kind of thing. And then I want to count how many had the matching sign.

I did find ways to compare whether two are identical but couldn't find anything which can do the above.

Thanks guys

 

[Dason]

You definitely don't want to do this in a loop

# make fake matrices

nrow <- 4
matA <- matrix(rnorm(nrow^2), nrow, nrow)
matB <- matrix(rnorm(nrow^2), nrow, nrow)

# create logical matrix indicating if signs are equal
logmat <- sign(matA) == sign(matB)
# count how many are equal
sum(logmat)

 

[sak]

Nice!

Thanks

 

[trinker]

Didn't know (or forgot about) sign myself.