R Logical Operators

Logical operators combine multiple conditions into one. They let you ask compound questions like "Is the age above 18 AND is the account active?" or "Is the score above 90 OR did the student get extra credit?" These operators return TRUE or FALSE based on the combined result.

The Three Core Logical Operators

Operator   Name    Meaning
────────────────────────────────────────────────────────
&          AND     Both conditions must be TRUE
|          OR      At least one condition must be TRUE
!          NOT     Reverses the logical value

AND Operator ( & )

AND requires both sides to be TRUE. If either side is FALSE, the result is FALSE.

age <- 25
income <- 50000

age > 18 & income > 30000    # TRUE & TRUE = TRUE
age > 18 & income > 60000    # TRUE & FALSE = FALSE

Truth table:
  TRUE  & TRUE  = TRUE
  TRUE  & FALSE = FALSE
  FALSE & TRUE  = FALSE
  FALSE & FALSE = FALSE

OR Operator ( | )

OR requires only one side to be TRUE. The result is FALSE only when BOTH sides are FALSE.

score <- 45
extra_credit <- TRUE

score >= 50 | extra_credit    # FALSE | TRUE = TRUE (passes!)
score >= 50 | !extra_credit   # FALSE | FALSE = FALSE

Truth table:
  TRUE  | TRUE  = TRUE
  TRUE  | FALSE = TRUE
  FALSE | TRUE  = TRUE
  FALSE | FALSE = FALSE

NOT Operator ( ! )

NOT flips the logical value. TRUE becomes FALSE, and FALSE becomes TRUE.

is_weekend <- FALSE
!is_weekend   # TRUE (it IS a weekday)

is_raining <- TRUE
!is_raining   # FALSE (it is NOT not-raining)

Scalar vs Vectorized Versions

Operator   Works On        Use In
─────────────────────────────────────────────
&          Vectors         Filtering, comparison
|          Vectors         Filtering, comparison
&&         Single value    if() conditions
||         Single value    if() conditions

# Vectorized (element-by-element)
c(TRUE, FALSE, TRUE) & c(TRUE, TRUE, FALSE)
# [1]  TRUE FALSE FALSE

# Scalar (only first element evaluated)
c(TRUE, FALSE) && c(TRUE, TRUE)
# [1] TRUE

Practical Example: Loan Eligibility

age    <- 32
salary <- 45000
credit <- 720

eligible <- age >= 21 & salary >= 25000 & credit >= 700

if (eligible) {
  cat("Loan approved\n")
} else {
  cat("Loan not approved\n")
}

Output:

Loan approved

Combining Multiple Conditions

x <- 15
# Is x between 10 and 20?
x > 10 & x < 20    # TRUE

# Is x outside the 10–20 range?
x < 10 | x > 20    # FALSE

# Is x NOT equal to 15?
!(x == 15)          # FALSE
x != 15             # FALSE (same result, simpler form)

Logical operators are the glue that holds complex conditions together. Every meaningful data filter in R — selecting specific rows, validating conditions, controlling program behavior — uses at least one of these operators.