[r] Opposite of %in%: exclude rows with values specified in a vector

A categorical variable V1 in a data frame D1 can have values represented by the letters from A to Z. I want to create a subset D2, which excludes some values, say, B, N and T. Basically, I want a command which is the opposite of %in%

D2 = subset(D1, V1 %in% c('B','N',T'))

Instead of creating your own function, it would be useful to just negate the behavior of

needle %in% haystack 

do this instead:

!(needle %in% haystack)

this works as well.

purrr::compose() is another quick way to define this for later use, as in:

`%!in%` <- compose(`!`, `%in%`)

The package collapse has it built in: %!in%.

Another solution could be using setdiff

D1 = c("A",..., "Z") ; D0 = c("B","N","T")

D2 = setdiff(D1, D0)

D2 is your desired subset.

The help for %in%, help("%in%"), includes, in the Examples section, this definition of not in,

"%w/o%" <- function(x, y) x[!x %in% y] #-- x without y

Lets try it:

c(2,3,4) %w/o% c(2,8,9)
[1] 3 4

Alternatively

"%w/o%" <- function(x, y) !x %in% y #--  x without y
c(2,3,4) %w/o% c(2,8,9)
# [1] FALSE  TRUE  TRUE

Using negate from purrr also does the trick quickly and neatly:

`%not_in%` <- purrr::negate(`%in%`)

Then usage is, for example,

c("cat", "dog") %not_in% c("dog", "mouse")

library(roperators)

1 %ni% 2:10

If you frequently need to use custom infix operators, it is easier to just have them in a package rather than declaring the same exact functions over and over in each script or project.

Hmisc has %nin% function, which should do this.

https://www.rdocumentation.org/packages/Hmisc/versions/4.4-0/topics/%25nin%25

If you look at the code of %in%

 function (x, table) match(x, table, nomatch = 0L) > 0L

then you should be able to write your version of opposite. I use

`%not in%` <- function (x, table) is.na(match(x, table, nomatch=NA_integer_))

Another way is:

function (x, table) match(x, table, nomatch = 0L) == 0L

How about:

'%ni%' <- Negate('%in%')
c(1,3,11) %ni% 1:10
# [1] FALSE FALSE  TRUE

This works fine for me:

`%nin%` <- Negate(`%in%`)

require(TSDT)

c(1,3,11) %nin% 1:10
# [1] FALSE FALSE  TRUE

For more information, you can refer to: https://cran.r-project.org/web/packages/TSDT/TSDT.pdf

Here is a version using filter in dplyr that applies the same technique as the accepted answer by negating the logical with !:

D2 <- D1 %>% dplyr::filter(!V1 %in% c('B','N','T'))