sapply()

sapply(X, FUN, ..., simplify = TRUE, USE.NAMES = TRUE)

sapply() is a user-friendly version of lapply() that attempts to simplify the result into a vector or matrix when the output can be reduced to a simpler data structure.

Syntax

sapply(X, FUN, ..., simplify = TRUE, USE.NAMES = TRUE)

Parameters

Parameter	Type	Default	Description
X	vector or list	—	A vector, list, or expression to iterate over
FUN	function	—	The function to apply to each element
...	arguments	—	Additional arguments passed to FUN
simplify	logical	TRUE	If TRUE, attempt to simplify the result
USE.NAMES	logical	TRUE	If TRUE and X has names, use them as names in the output

Examples

Basic usage

# Square each element
sapply(1:5, function(x) x^2)
# [1]  1  4  9 16 25

# Using a built-in function
sapply(c("hello", "world"), toupper)
# [1] "HELLO" "WORLD"

With names preserved

names <- c("alice", "bob", "charlie")
sapply(names, function(x) paste0(toupper(substr(x, 1, 1)), substr(x, 2, nchar(x))))
#    alice      bob  charlie 
#  "Alice"    "Bob" "Charlie"

Returning a matrix

# When results have length > 1, sapply creates a matrix
sapply(1:3, function(x) c(x, x^2, x^3))
#      [,1] [,2] [,3]
# [1,]    1    2    3
# [2,]    1    4    9
# [3,]    1    8   27

With additional arguments

# Pass extra arguments to FUN
sapply(c(10, 20, 30), round, digits = -1)
# [1] 10 20 30

Working with lists

df_list <- list(
  a = data.frame(x = 1:3, y = 4:6),
  b = data.frame(x = 7:9, y = 10:12)
)

sapply(df_list, nrow)
# a b 
# 3 3

sapply(df_list, function(df) sum(df$x))
#  a  b 
#  6 24

Common Patterns

Data transformation pipeline

# Apply multiple transformations
data <- list(
  c(1, 2, 3),
  c(4, 5, 6),
  c(7, 8, 9)
)

sapply(data, function(x) {
  x <- x + 1
  x <- x / mean(x)
  round(x, 2)
})
#       [,1]  [,2]  [,3]
# [1,]  0.67  0.67  0.67
# [2,]  1.33  1.33  1.33
# [3,]  2.00  2.00  2.00

Conditional processing

values <- list(a = 1:5, b = c(2, 4, 6), c = c(1, 3, 5, 7))
sapply(values, function(x) if(all(x %% 2 == 0)) "all even" else "has odd")
#                  a          b          c 
# "has odd" "all even" "has odd"

Handling missing values

vec <- c(1, 2, NA, 4, NA, 6)
sapply(vec, function(x) ifelse(is.na(x), 0, x))
# [1] 1 2 0 4 0 6

How sapply Differs from lapply

Aspect	lapply	sapply
Output	Always a list	Tries to simplify to vector/matrix
Use case	When you need list output	When you want convenient vector output
Safety	More predictable	Can fail silently if simplification fails

When simplify = FALSE, sapply() behaves exactly like lapply().

See Also

• base::lapply
• base::apply
• purrr::map