intersect()

intersect(x, y)

The intersect() function returns the elements that appear in both of two vectors. It is useful for comparing IDs, categories, or labels shared between datasets.

Syntax

intersect(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)
y <- c(3, 4, 5, 6)

intersect(x, y)
# [1] 3 4

Character vectors

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

intersect(a, b)
# [1] "banana" "cherry"

Finding common IDs

# Users who purchased both products
product_a_buyers <- c("user_1", "user_2", "user_3", "user_4")
product_b_buyers <- c("user_3", "user_4", "user_5", "user_6")

intersect(product_a_buyers, product_b_buyers)
# [1] "user_3" "user_4"

Common Patterns

Filtering based on another dataset

# Active users from a larger user list
all_users <- c("user_1", "user_2", "user_3", "user_4", "user_5")
active_users <- c("user_1", "user_3", "user_5")

intersect(all_users, active_users)
# [1] "user_1" "user_3" "user_5"

Common elements from multiple vectors

a <- c(1, 2, 3)
b <- c(2, 3, 4)
c <- c(3, 4, 5)

intersect(intersect(a, b), c)
# [1] 3

See Also

• base::setdiff
• base::union
• base::unique