e1 op e2 <BR> <BR>
==
or !=.
NA
s) are allowed.
FALSE
or
TRUE
in each element
according to the truth of the element-wise comparison of the operands.
>
greater than
<
less than
>=
greater than or equal to
<=
less than or equal to
==
equal to
!=
not equal to
An
NA
element of
e1
or
e2
results in an
NA
element of the answer.
These are members of the
Ops
group of generic functions.
For complex data
op
orders first on the real part, then
on the imaginary part if necessary.
For character data, ordering is by the ASCII character set.
See section 5.6 of Becker, Chambers and Wilks
for the rules for dealing with operands with attributes.
To test for missing values use
is.na
.
To test for a
NULL
value use
is.null
.
When comparing floating point numbers, you may wish to allow for small
differences, e.g.
abs(x-y) < 1E-6
rather than testing for exact equality using
identical(x,y)
is useful in many cases
in place of
x==y
, e.g. for non-numerical
objects, or to compare objects of different lengths.
x == y
.
You need to leave a space between a "
<
" operator and a negative
number because "
<-
" is always interpreted as the assignment operator.
This is a very unusual case, spaces generally make no difference.
This function will be used as the default method for classes that do not inherit a specific method for the function or for the Ops group of functions. The result will retain the class and the attributes. If this behavior is not appropriate, the designer of the class should provide a method for the function or for the Ops group
a > b # true when 'a' greater than 'b' x[x > 100] # all 'x' values larger than 100 state == "Wyoming" x == NA # probably not what you want is.na(x) # indicates which elements are missing x == NULL # probably not what you want is.null(x) identical(x, NULL) length(x)==1 && class(x) == "logical" && x identical(x, T) # easier way