For two vectors or scalars
a and
b,
a %in% b
returns a vector of logical values corresponding to
the elements in
a. A value is
T if that element of
a is
found somewhere in
b,
F otherwise. If
a is a factor object
and
b is numeric, converts
a to its integer codes before
the comparison. If
a is numeric and
b is
factor, converts
b
to codes.
%nin% returns
T if the element in
a is not in
b.
USAGE:
a %in% b
a %nin% b
ARGUMENTS:
a
a vector (numeric, character, factor)
b
a vector (numeric, character, factor), matching the mode of a
VALUE:
vector of logical values with length equal to length of
a.
SEE ALSO:
EXAMPLES:
w <- factor(c("a","b","c"))
w %in% c("b","c")
w %in% c(2,3) #same as previous, but with warning
#Suppose that a variable x has levels "a", "b1", "b2" and you
#want to classify levels "b1" and "b2" as just "b". You can use
#the %in% operator and do the following:
# levels(x)[levels(x) %in% c("b1","b2")] <- "b"
#Note that levels(x) <- list(b=c('b1','b2')) would be a better approach