setdiff()

setdiff(x, y)

The setdiff() function returns elements that are in the first vector but not in the second. It performs a set difference operation.

Syntax

setdiff(x, y)

Parameters

Parameter	Type	Description
x	vector	First input vector
y	vector	Second input vector

Examples

Basic usage

x <- c(1, 2, 3, 4, 5)
y <- c(3, 4, 5, 6, 7)

setdiff(x, y)
# [1] 1 2

Character vectors

a <- c("apple", "banana", "cherry")
b <- c("banana", "cherry", "date")

setdiff(a, b)
# [1] "apple"

Order is preserved

x <- c(5, 3, 1, 4, 2)
y <- c(4, 2)

setdiff(x, y)
# [1] 5 3 1

Common Patterns

Finding unique rows in one data frame vs another

df1 <- data.frame(id = 1:5)
df2 <- data.frame(id = 3:7)
ids1 <- df1$id
ids2 <- df2$id
new_ids <- setdiff(ids1, ids2)
df1[df1$id %in% new_ids, ]
#   id
# 1  1
# 2  2

Removing handled cases

# All cases minus already processed
all_cases <- 1:100
processed <- c(5, 10, 15, 20)
remaining <- setdiff(all_cases, processed)
length(remaining)
# [1] 96

See Also

• base::union
• base::intersect
• base::unique