CODEWITHSUNDEEP
r
Electrino
Electrino

Reputation: 2890

How to remove matching characters in R?

Seems like an easy question but the solution is alluding me. I'm basically trying to remove matching characters from 2 variables in R. The simple code below will hopefully illustrate what I'm trying to do.

If I have 2 variables x, y and they are filled with characters, like so:

x <- c("A", "B", "C", "D")
y <- "C"

What I'm trying to do is to search through x... and any characters that match the characters in y, I want to remove from x. So, in this instance, the only character that matches is C... so I want to remove C from x. Effectively, Im trying to do:

x[-3]

However, in practise, this method won't work for me. I was trying to achieve this by doing something like:

x <- x[,-which(names(x) %in% y)] # This won't work because x is not a data frame with cols

or

x <- subset(x, select=-y) # this throws back an error saying subset is missing

But I can't get these methods to work with characters... any suggestions?

Upvotes: 0

Views: 71

Answers (1)

Gregor Thomas
Gregor Thomas

Reputation: 145755

x doesn't have names, so use x, not names(x). Also x is a vector, not a data frame, so your extra comma x[,] in the brackets won't work.

# fix those issues and this:
x[,-which(names(x) %in% y)] 
# becomes this:
x[-which(x %in% y)]

# as phiver points out in comments, `which()` isn't needed, and we can use
x[!x %in% y] 

# many people like to define a "not in" function for this
'%nin%' = Negate(%in%)
x[x %nin% y]

Upvotes: 2

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