heavy rocker dude - 3 months ago 8
R Question

# What do the %op% operators in mean in R? For example "%in%"

I tried to do this simple search but couldn't find anything on the percent (

`%`
) symbol in R. What does
`%in%`
mean in the following code?

``````time(x) %in% time(y)
``````

`x`
and
`y`
are matrices.

How do I look up help on
`%in%`
and similar functions that follow the
`%stuff%`
pattern, as I cannot locate the help file?

Related questions:

What does eg %+% do? in R

The R %*% operator

What does %*% mean in R

https://stackoverflow.com/questions/23091654/what-does-it-mean-when-something-is-between-two-percent-signs-in-r

What does %||% do in R?

What does %>% mean in R

Put quotes around it to find the help page. Either of these work

``````> help("%in%")
> ?"%in%"
``````

Once you get to the help page, you'll see that

‘%in%’ is currently defined as

‘"%in%" <- function(x, table) match(x, table, nomatch = 0) > 0’

Since `time` is a generic, I don't know what `time(X2)` returns without knowing what `X2` is. But, `%in%` tells you which items from the left hand side are also in the right hand side.

``````> c(1:5) %in% c(3:8)
[1] FALSE FALSE  TRUE  TRUE  TRUE
``````

See also, `intersect`

``````> intersect(c(1:5), c(3:8))
[1] 3 4 5
``````