These predicates check whether R considers a number vector to be
integer-like, according to its own tolerance check (which is in
fact delegated to the C library). This function is not adapted to
data analysis, see the help for `base::is.integer()`

for examples
of how to check for whole numbers.

Things to consider when checking for integer-like doubles:

This check can be expensive because the whole double vector has
to be traversed and checked.

Large double values may be integerish but may still not be
coercible to integer. This is because integers in R only support
values up to `2^31 - 1`

while numbers stored as double can be
much larger.