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x <- c("a", "b", "c", "d", "e", "f", "g")
y <- c("a", "c", "d", "z")

I am trying to compare y to x and find an index where in y that does not match with anything in x. in this case z does match and I want R to return the index of z.

This is one of the things I tried and it does not work.

index <- which(y != x)
MrFlick
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kgwarishi malatji
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  • If you just need the values rather than the indexes, use https://stackoverflow.com/questions/1837968/how-to-tell-what-is-in-one-vector-and-not-another – MrFlick Feb 19 '20 at 03:23

2 Answers2

3

use the operator %in%

 which(!y%in%x)
Filippo
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1

You can also use match which will return NA if there is no match. 

which(is.na(match(y, x)))
#[1] 4

Or another variation with setdiff

which(y %in% setdiff(y, x))
Ronak Shah
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