Hello,
#I have two matrices, eg.:
y <- matrix( c(20, NA, NA, 45, 50, 19, 32, 101, 10, 22, NA, NA, 80,
49, 61, 190), ncol=4 )
x <- matrix( c(20, NA, NA, NA, 50, 19, 32, 101, 10, 22, NA, NA, 80,
49, 61, 190), ncol=4 )
#Whereas x contains all NA�s from y plus some additional NA�s.
#I want to find the index of these additional NA�s. I think, there must be a
very easy way to do this.
#Here are the indices of NA�s in x and y:
l1 <- which(is.na(x), arr.ind=TRUE)
l2 <- which(is.na(y), arr.ind=TRUE)
#> l1
# [,1] [,2]
#[1,] 2 1
#[2,] 3 1
#[3,] 4 1
#[4,] 3 3
#[5,] 4 3
#> l2
# row col
#[1,] 2 1
#[2,] 3 1
#[3,] 3 3
#[4,] 4 3
#Now I want to find a matrix, which includes the values of l1, without the rows
of l2,
#which has equal entities (the index of the additional NA�S).
#In this example the result should be row 3 of l1 with the values 4 and 1.
#The following code works, but I think there must be a much more elegant way to
do this.
l3 <- l1
l3 <- cbind( l1, rep(0, nrow(l1)) )
num <- 1
for( i in 1:nrow(l1) ){
for( j in 1:nrow(l2) ){
if( l1[i,1] == l2[j,1] & l1[i,2] == l2[j,2]){
l3[i,3] <- 1
}
}
}
l4 <- l3[l3[,3]==0, c(1,2)]
#> l4
#row col
# 4 1
I have often such problems like this and I assume, that other people have
similar tasks.
My question is: Does anybody know a function in one package, which compares
rows of two matrices like this or have anybody an idea to do this in a much
more elegant way"?
Thank you very much,
Matthias
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