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What do the %op% operators in mean? 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) where 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:

Solution

  • 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