Apply a Function over a List of elements in R Programming – lapply() Function

lapply() function in R Programming Language is used to apply a function over a list of elements. 

lapply() function is used with a list and performs the following operations:

lapply(List, length): Returns the length of objects present in the list, List.
lapply(List, sum): Returns the sum of elements held by objects in the list, List.
lapply(List, mean): Returns the mean of elements held by objects in the list, List.
lapply(List, cumsum): Returns the cumulative sum of elements held by objects present inside the list, List.

Syntax: lapply(list, func)

Parameters:

• list: list of elements

 R – Apply a Function over a List of elements

Example 1: Basic example of lapply() Function in R programming

R

# R program to illustrate
# lapply() function

# Creating a matrix
A = matrix(1:9, 3, 3)

# Creating another matrix
B = matrix(10:18, 3, 3)

# Creating a list
myList = list(A, B)

# applying lapply()
determinant = lapply(myList, det)
print(determinant)

Output:

[[1]]
[1] 0

[[2]]
[1] 5.329071e-15

Example 2: Apply a Function over a List of elements in R

R

# R program to illustrate
# lapply() function

# Creating a matrix
A = matrix(1:9, 3, 3)

# Creating another matrix
B = matrix(10:18, 3, 3)

# Creating a list
myList = list(A, B)

# applying lapply()
sum = lapply(myList, sum)
print(sum)

Output:

     [, 1] [, 2] [, 3]
[1, ]    1    4    7
[2, ]    2    5    8
[3, ]    3    6    9
[1]  28  80 162
[1]   6 120 504