Reworking someone else R code. What is %in%

Question

I am trying to adapt someone else's R code for my needs.

I do not know what this line does:

names(train_clean) %in% names(test_clean)

I understand names(train_clean). I understand names(test_clean).

I do not know what %in% is? Looking for help with ? is not helpful in the instance.

?%in% 

yields Error: unexpected SPECIAL in "?%in%"

Answer 1

Try ?'%in%'.

It returns a logical vector, telling you wether a vector contains one or more of a following vector. As an example:

c(1:10) %in% c(1,5)
#>  [1]  TRUE FALSE FALSE FALSE  TRUE FALSE FALSE FALSE FALSE FALSE