These operators act on raw, logical and number-like vectors.
! x x & y x && y x | y x || y xor(x, y)isTRUE(x)
! 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
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 length as
x: names, dims and dimnames are copied from
x, and all other attributes (including class) if no coercion is done.For
xora 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
warningwhen 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
tspattribute 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.For
isTRUE, a length-one logical vector.
The elementwise operators are sometimes called as functions as e.g.
`&`(x, y): see the description of how argument-matching is done
| are S4 generics, the latter two part
Logic group generic (and
hence methods need argument names
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
Syntax for operator precedence.
bitwAnd for bitwise versions for integer vectors.
y <- 1 + (x <- stats::rpois(50, lambda = 1.5) / 4 - 1) x[(x > 0) & (x < 1)] # all x values between 0 and 1 if (any(x == 0) || any(y == 0)) "zero encountered" ## construct truth tables : x <- c(NA, FALSE, TRUE) names(x) <- as.character(x) outer(x, x, "&") ## AND table outer(x, x, "|") ## OR table