Apply Functions

The Apply Family

R's apply functions let you apply a function to elements of a data structure without writing explicit loops.

sapply() -- Simplify Apply

Applies a function to each element of a vector and simplifies the result:

x <- c(1, 4, 9, 16, 25)
result <- sapply(x, sqrt)
cat(result, "\n")  # 1 2 3 4 5

lapply() -- List Apply

Like sapply() but always returns a list:

x <- c(1, 4, 9)
result <- lapply(x, sqrt)
# result is a list: list(1, 2, 3)

vapply() -- Verified Apply

Like sapply() but you specify the expected return type for safety:

x <- c(1, 4, 9)
result <- vapply(x, sqrt, numeric(1))
cat(result, "\n")  # 1 2 3

apply() -- For Matrices

Apply a function to rows or columns of a matrix:

m <- matrix(1:6, nrow = 2, byrow = TRUE)
cat(apply(m, 1, sum), "\n")  # Row sums: 6 15
cat(apply(m, 2, sum), "\n")  # Col sums: 5 7 9

The second argument is the margin: 1 for rows, 2 for columns.

With Anonymous Functions

result <- sapply(1:5, function(x) x ^ 2 + 1)
cat(result, "\n")  # 2 5 10 17 26

Your Task

Use sapply() to compute the cube of each number from 1 to 5. Print the result.