These operators act on raw, logical and number-like vectors.
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raw or logical or ‘number-like’ vectors (i.e., of types
! indicates logical negation (NOT).
&& indicate logical AND and
indicate logical OR. The shorter form performs elementwise
comparisons in much the same way as arithmetic operators. The longer
form evaluates left to right examining only the first element of each
vector. Evaluation proceeds only until the result is determined. The
longer form is appropriate for programming control-flow and typically
xor indicates elementwise exclusive OR.
isTRUE(x) is an abbreviation of
identical(TRUE, x), and
so is true if and only if
x is a length-one logical vector
whose only element is
TRUE and which has no attributes (not even
Numeric and complex vectors will be coerced to logical values, with
zero being false and all non-zero values being true. Raw vectors are
handled without any coercion for
xor, with these operators being applied bitwise (so
| are generic functions:
methods can be written for them individually or via the
Ops (or S4
Logic, see below)
group generic function. (See
how dispatch is computed.)
NA is a valid logical object. Where a component of
NA, the result will be
NA if the
outcome is ambiguous. In other words
NA & TRUE evaluates to
NA & FALSE evaluates to
FALSE. See the
See Syntax for the precedence of these operators: unlike many other languages (including S) the AND and OR operators do not have the same precedence (the AND operators have higher precedence than the OR operators).
!, a logical or raw vector(for raw
x) of the same
x: names, dims and dimnames are copied from
and all other attributes (including class) if no coercion is done.
xor a logical or raw vector. If
involving a zero-length vector the result has length zero. Otherwise,
the elements of shorter vectors are recycled as necessary (with a
warning when they are recycled only fractionally).
The rules for determining the attributes of the result are rather
complicated. Most attributes are taken from the longer argument, the
first if they are of the same length. Names will be copied from the
first if it is the same length as the answer, otherwise from the
second if that is. For time series, these operations are allowed only
if the series are compatible, when the class and
attribute of whichever is a time series (the same, if both are) are
used. For arrays (and an array result) the dimensions and dimnames
are taken from first argument if it is an array, otherwise the second.
isTRUE, a length-one logical vector.
| are S4 generics, the latter two part
Logic group generic (and
hence methods need argument names
The elementwise operators are sometimes called as functions as
`&`(x, y): see the description of how
argument-matching is done in
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
all for OR and AND on many scalar
Syntax for operator precedence.
bitwAnd for bitwise versions for integer vectors.
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