Exclude Lines In Based In Multiple Strings In R

Question

[viniciushs88]

I would like to exclude entire lines in matrix "Y" based in 2 collumns in matrix "X":

Matrix "X":

number1  number2  inf
 gen1     genx1   223
 gen1     genx2   221
 gen2     genx3   224
 gen2     genx5   225

Matrix "Y":

numberall  inf
gen1      223
genx1     256
gen2      225
genx2     214
gen3      563
genx3     235
gen4      256
genx4     568

Expected output matrix

numberall  inf
gen3      563
gen4      256
genx4     568

Cheers.

Answer 1

[Chris Miller]

I believe something like this will work:

#make a list of all terms you want to exclude
exclude = c(x[,1],x[,2])
#keep only those that aren't in your list
new.y = y[!(y[,1] %in% exclude),]

[Michael]

%in% also works with a matrix, so you don't need exclude = c(x[,1],x[,2]):

> mat = matrix(c(letters[1:8]),nrow=4,ncol=2)
> letters[!letters %in% mat]
[1] "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z"

[Devon Ryan]

That's good to know!

Answer 2

[Devon Ryan]

EXCLUDE <- union(which(Y[,1] %in% X[,1]), which(Y[,1] %in% X[,2]))
Y[-EXCLUDE,]

Edit: Chris beat me to it with a similar method.

Edit2: Apparently one can also simply:

Y[-which(Y[,1] %in% X),]

which requires less typing.