最近在使用R语言进行数据探索时，发现逻辑操作 & 和 && 代表的是两种逻辑操作，这里整理一下R中的逻辑操作符，以下是Qucik-R的操作符介绍：

Operators

R’s binary and logical operators will look very familiar to programmers. Note that binary operators work on vectors and matrices as well as scalars.

Arithmetic Operators

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Operator Description
+	addition
-	subtraction
*	multiplication
/	division
^ or **	exponentiation
x %% y	modulus (x mod y) 5%%2 is 1
x %/% y	integer division 5%/%2 is 2

Logical Operators

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Operator	Description
<	less than
<=	less than or equal to
>	greater than
>=	greater than or equal to
==	exactly equal to
!=	not equal to
!x	Not x
x | y	x OR y
x & y	x AND y
isTRUE(x)	test if X is TRUE

示例

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# An example 
x <- c(1:10)
x[(x>8) | (x<5)]
# yields 1 2 3 4 9 10
# How it works 
x <- c(1:10)
x
1 2 3 4 5 6 7 8 9 10
x > 8
F F F F F F F F T T
x < 5
T T T T F F F F F F
x > 8 | x < 5
T T T T F F F F T T
x[c(T,T,T,T,F,F,F,F,T,T)]
1 2 3 4 9 10

&与&&，|与||区别

&和|称为短逻辑符，&&及||称为长逻辑符，长逻辑符只比较左边和右边的第一个元素，而短逻辑符会比较所有元素。通过示例来看：

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> a<-c(TRUE, FALSE, TRUE, FALSE)
> b<-c(FALSE, FALSE, TRUE, TRUE)
> c<-c(TRUE, FALSE, FALSE, FALSE)
> a & b
[1] FALSE FALSE  TRUE FALSE
> a && b
[1] FALSE
> a & c
[1]  TRUE FALSE FALSE FALSE
> a && c
[1] TRUE
> a | b
[1]  TRUE FALSE  TRUE  TRUE
> a || b
[1] TRUE
> a | c
[1]  TRUE FALSE  TRUE FALSE
> a || c
[1] TRUE