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 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 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