Section 14 R Atomic Class: Logical

• A logical vector is TRUE or FALSE

• It is the R representation of Boolean data

• The logical vector is very helpful for comparisons

• A logical vector is created by typing TRUE or FALSE (uppercase without the quote marks)

• R also assume T and F as shorthand for TRUE or FALSE

• Enclosing TRUE or FALSE by quotes will render it to a character vector

• Function to identify the object type: class, typeof, mode

• Other functions to check the object type as logical: is.logical

14.1 Examples

x <- TRUE
class(x)
typeof(x)
is.logical(x)

y <- T
class(y)

z <- F
class(z)
is.logical(z)

14.2 Examples: comparison

• R uses operators ==, !=, >, <, >= and <= for logical comparisons

Operator	Explanation	Example
==	x EQUAL y?	x == y
!=	x NOT EQUAL y?	x != y
<	x LESS THAN y?	x < y
<=	x LESS THAN OR EQUAL y?	x <= y
>	x GREATER THAN y?	x > y
>=	x GREATER THAN OR EQUAL y?	x >= y

x <- 15
y <- 3
z <- x > y
z

x <- -3.5
y <- 4
z <- x > y
z

x <- 'A'
y <- 'a'
z <- x > y
z


x <- 'A'
y <- 'Z'
z <- x > y
z


x <- 'z'
y <- 'A'
z <- x > y
z


x <- 'apple'
y <- 'grape'
z <- x > y
z


x <- 'grape'
y <- 'banana'
z <- x > y
z


x <- TRUE
y <- FALSE
z <- x > y
z


x <- T
y <- F
z <- x > y
z

14.3 Examples: more comparisons

• R uses operators ==, >, <, >= and <= for comparisons

• R also uses operators ! (NOT), & (AND) and | (OR)

Operator	Meaning	X	Y	Decision	Example
&	AND	TRUE	TRUE	TRUE	X & Y
&	AND	TRUE	FALSE	FALSE	X & Y
&	AND	FALSE	TRUE	FALSE	X & Y
&	AND	FALSE	FALSE	FALSE	X & Y
|	OR	TRUE	TRUE	TRUE	X | Y
|	OR	TRUE	FALSE	TRUE	X | Y
|	OR	FALSE	TRUE	TRUE	X | Y
|	OR	FALSE	FALSE	FALSE	X | Y

x <- 10L
y <- 5L

z1 <- x + y
z2 <- x - y
z3 <- x

x; y
z1; z2; z3

m <- (x > z1) & (x > z2)
m

n <- (x == z1) & (x < z2)
n

p <- (y > z1) & (y > z2)
p

q <- (y >= z1) & (y <= z2)
q

r <- (y >= z1) | (y <= z2)
r

s <- (x >= z1) | (y >= z3)
s


t <- !(x >= z2) | (y >= z3)
t