According to help('percent in percent'), percent in percent is a value matching function that "returns a vector of the places of (first) matches of its first parameter in its second." This implies that you might compare vectors of various lengths to determine whether at least one element in one vector matches an element in another. The output will have a length equal to the vector being compared (the first one).
1:2 in percentage return (1:2,5)
# True, True
Replicate (1:2,5) in percent 1:2 # True, True, True, True, True, True, True
The output is longer in seconds; take note.
If two things are exactly equal, the comparison operator == is used. The elements of the vectors will be compared element-by-element if they are similar in length. Vectors will be recycled if not. The output's length