%in% on numeric values returns wrong result

Question

6969277959563657216 is not one of the following numbers, yet %in% returns TRUE.

6969277959563657216  %in% c(6972646901044805634,
                            6935914801507893250,
                            6930019021496532993,
                            6969277959563657217,
                            7005257783989764866)
[1] TRUE

Why is this?

Might be relevant: https://stackoverflow.com/questions/22466328/how-to-work-with-large-numbers-in-r — Harrison Jones, Oct 28 '21 at 16:52
typecast to character before making the comparison, since this is a precision error — Parseltongue, Oct 28 '21 at 17:05

tpetzoldt · Answer 1 · 2021-10-28T17:07:35.703

The reason is that most computer programs work with a precision of approx. 16 digits, see FAQ 7.31 Why doesn’t R think these numbers are equal? and the link therein. The interpretation here is of course: "Why does R think these numbers are equal".

Example:

6969277959563657216 == 6969277959563657217
[1] TRUE

More about this also on Wikipedia and several other places.

Edit: Here a SO posting about big integers long/bigint/decimal equivalent datatype in R

%in% on numeric values returns wrong result

1 Answers1