Logic
Logical Operators
Description
Operators work on logical or number-like vectors. The operators are
& (and), | (or), ! (not), or
xor(x,y) (exclusive or) .
Usage
e1 & e2
e1 | e2
! e1
xor(x, y)
Arguments
| x, y |
a logical or number-like vector of objects. The mode of a number-like
vector could be "integer", "double" or "raw".
Missing values (NAs) are allowed.
|
Details
Results corresponding to NA
in the operands will be either a logical value or an NA, depending on
whether the other operand uniquely determines the answer. For example,
NA|TRUE must be TRUE, and NA&FALSE must be FALSE.
See section 5.1.5 of Becker, Chambers and Wilks (1988)
for the rules for dealing with operands with attributes.
All number-like non-raw vectors will be coerced to logical: zero value
will be FALSE and non-zero value will be TRUE.
All raw vectors will not be coerced, and will return the result of bitwise operation.
Logic is a group generic function,
including a subset of
functions included under the Ops
group generic function.
You can find the current list of functions in this group by
typing getGroupMembers("Logic").
Value
returns a logical vector of using & (and), | (or),
! (negation), or xor(x, y) (exclusive or) if
x, y are logical vectors or non-raw number-like vectors.
If the number-like vector has the mode "raw", it returns a
raw vector containing the result of a bitwise operation. The result
is as long as the longer of the operands for all but negation.
Classes
The !, &, and | operators make up the Logic group
of operators within the Ops group.
References
Becker, R.A., Chambers, J.M., and Wilks, A.R. (1988).
The New S Language
Wadsworth and Brooks/Cole, Pacific Grove, CA.
Differences between Spotfire Enterprise Runtime for R and Open-source R
In open-source R, the negation (!) operator is not a group member of Logic.
See Also
if for
|| (sequential or) and
&& (sequential and).
Compare,
Groups,
Ops,
and individual functions listed below.
Examples
# The Ops group of generic functions includes:
# Arithmetic: +, -, *, /, ^, %/%, %%
# Comparison: >, <, >=, <=, ==, !=, compare
# Logical: !, &, |
# See also .Uminus and xor
cu <- Sdatasets::cu.summary
# Cars made in USA or Japan or both:
cu[cu$Country=="USA"
| cu$Country=="Japan/USA"
| cu$Country == "Japan", ]
# Rows of cu.summary with no NA's in either Reliability or Mileage:
cu[!is.na(cu$Reliability) & !is.na(cu$Mileage), ]
# Cars with Mileages outside the interquartile range exclusive of NA's:
safe <- !is.na(cu$Mileage)
cu[xor(cu$Mileage > 21,
cu$Mileage < 27) & safe, ]
# Logic tables for &, | and xor:
a <- c(TRUE, FALSE, NA)
outer(a, a,"&")
outer(a, a, "|")
outer(a, a, "xor")
# Other "numeric" type
e1 <- c(1, 3, 0, 3, NA, 0)
e2 <- c(3, 0, 0, 2, -5, NA)
e1 & e2 # Result: TRUE FALSE FALSE TRUE NA FALSE
e1 | e2 # Result: TRUE TRUE FALSE TRUE TRUE NA
!e1 # Result: FALSE FALSE TRUE FALSE NA TRUE
xor(e1, e2) # Result: FALSE TRUE FALSE FALSE NA NA
# "raw" type, the shorter length of vector is recycled.
e1.raw <- as.vector(c(42, 54, 13, 0, 18, 25), mode = "raw")
e2.raw <- as.vector(c(17, 0, 5, NA), mode = "raw")
e1.raw & e2.raw # Result: 00 00 05 00 10 00
e1.raw | e2.raw # Result: 3b 36 0d 00 13 19
!e1.raw # Result: d5 c9 f2 ff ed e6
xor(e1.raw, e2.raw) # Result: 3b 36 08 00 03 19