R-Lists

Last Updated : 06 Jun, 2025

A list in R programming is a generic object consisting of an ordered collection of objects. Lists are one-dimensional, heterogeneous data structures. The list can be a list of vectors, a list of matrices, a list of characters, a list of functions, and so on. A list in R is created with the use of the list() function.

R allows accessing elements of an R list with the use of the index value. In R, the indexing of a list starts with 1 instead of 0.

1. Creating a List

To create a List in R you need to use the function called "list()". We want to build a list of employees with the details. So for this, we want attributes such as ID, employee name, and the number of employees.

Example:

empId = c(1, 2, 3, 4)  empName = c("Debi", "Sandeep", "Subham", "Shiba") numberOfEmp = 4   empList = list(empId, empName, numberOfEmp)   print(empList)

Output

[[1]] [1] 1 2 3 4  [[2]] [1] "Debi"    "Sandeep" "Subham"  "Shiba"    [[3]] [1] 4

2. Naming List Components

Naming list components make it easier to access them.

Example:

my_named_list <- list(name = "Sudheer", age = 25, city = "Delhi") print(my_named_list)

Output

$name [1] "Sudheer"  $age [1] 25  $city [1] "Delhi"

3. Accessing R List Components

We can access components of an R list in two ways.

3.1. Access components by names:

All the components of a list can be named and we can use those names to access the components of the R list using the dollar command.

Example:

empId = c(1, 2, 3, 4) empName = c("Debi", "Sandeep", "Subham", "Shiba") numberOfEmp = 4  empList = list(   "ID" = empId,   "Names" = empName,   "Total Staff" = numberOfEmp   ) print(empList)  cat("Accessing name components using $ command\n") print(empList$Names)

Output

$ID [1] 1 2 3 4  $Names [1] "Debi"    "Sandeep" "Subham"  "Shiba"    $`Total Staff` [1] 4  Accessing name components using $ command [1] "Debi"    "Sandeep" "Subham"  "Shiba"

3.2. Access components by indices:

We can also access the components of the R list using indices. To access the top-level components of a R list we have to use a double slicing operator "[[ ]]" which is two square brackets and if we want to access the lower or inner-level components of a R list we have to use another square bracket "[ ]" along with the double slicing operator "[[ ]]".

Example:

empId = c(1, 2, 3, 4) empName = c("Debi", "Sandeep", "Subham", "Shiba") numberOfEmp = 4  empList = list(   "ID" = empId,   "Names" = empName,   "Total Staff" = numberOfEmp ) print(empList)  cat("Accessing name components using indices\n") print(empList[[2]])  cat("Accessing Sandeep from name using indices\n") print(empList[[2]][2])  cat("Accessing 4 from ID using indices\n") print(empList[[1]][4])

Output

$ID [1] 1 2 3 4  $Names [1] "Debi"    "Sandeep" "Subham"  "Shiba"    $`Total Staff` [1] 4  Accessing name components using indices [1] "Debi"    "Sandeep" "Subham"  "Shiba"   Accessing Sandeep from na...

4. Modifying Components of a List

A R list can also be modified by accessing the components and replacing them with the ones which you want.

Example:

empId = c(1, 2, 3, 4) empName = c("Debi", "Sandeep", "Subham", "Shiba") numberOfEmp = 4  empList = list(   "ID" = empId,   "Names" = empName,   "Total Staff" = numberOfEmp ) cat("Before modifying the list\n") print(empList)  empList$`Total Staff` = 5 empList[[1]][5] = 5 empList[[2]][5] = "Kamala"  cat("After modified the list\n") print(empList)

Output

Before modifying the list $ID [1] 1 2 3 4  $Names [1] "Debi"    "Sandeep" "Subham"  "Shiba"    $`Total Staff` [1] 4  After modified the list $ID [1] 1 2 3 4 5  $Names [1] "Debi"    "Sandeep" "Subham" ...

5. Concatenation of lists

Two R lists can be concatenated using the concatenation function. So, when we want to concatenate two lists we have to use the concatenation operator.

Syntax

list = c(list, list1)
list = the original list
list1 = the new list

Example:

empId = c(1, 2, 3, 4) empName = c("Debi", "Sandeep", "Subham", "Shiba") numberOfEmp = 4  empList = list(   "ID" = empId,   "Names" = empName,   "Total Staff" = numberOfEmp ) cat("Before concatenation of the new list\n") print(empList)  empAge = c(34, 23, 18, 45) empList = c(empName, empAge)  cat("After concatenation of the new list\n") print(empList)

Output

Before concatenation of the new list $ID [1] 1 2 3 4  $Names [1] "Debi"    "Sandeep" "Subham"  "Shiba"    $`Total Staff` [1] 4  After concatenation of the new list [1] "Debi"    "Sandeep" "Subham"  "S...

6. Adding Item to List

To add an item to the end of list, we can use append() function.

my_numbers = c(1,5,6,3) append(my_numbers, 45) my_numbers

Output

[1]  1  5  6  3 45 [1] 1 5 6 3

7. Deleting Components of a List

To delete components of a R list, first of all, we need to access those components and then insert a negative sign before those components. It indicates that we had to delete that component.

Example:

empId = c(1, 2, 3, 4) empName = c("Debi", "Sandeep", "Subham", "Shiba") numberOfEmp = 4  empList = list(   "ID" = empId,   "Names" = empName,   "Total Staff" = numberOfEmp ) cat("Before deletion the list is\n") print(empList)  cat("After Deleting Total staff components\n") print(empList[-3])  cat("After Deleting sandeep from name\n") print(empList[[2]][-2])

Output

Before deletion the list is $ID [1] 1 2 3 4  $Names [1] "Debi"    "Sandeep" "Subham"  "Shiba"    $`Total Staff` [1] 4  After Deleting Total staff components $ID [1] 1 2 3 4  $Names [1] "Debi"    "Sand...

8. Merging list

We can merge the R list by placing all the lists into a single list.

lst1 <- list(1,2,3) lst2 <- list("Sun","Mon","Tue") new_list <- c(lst1, lst2) print(new_list)

Output:

[[1]]
[1] 1
[[2]]
[1] 2
[[3]]
[1] 3
[[4]]
[1] "Sun"
[[5]]
[1] "Mon"
[[6]]
[1] "Tue"

9. Converting List to Vector

Here we are going to convert the R list to vector, for this we will create a list first and then unlist the list into the vector.

lst <- list(1:5) print(lst) vec <- unlist(lst) print(vec)

Output

[[1]] [1] 1 2 3 4 5  [1] 1 2 3 4 5

10. R List to matrix

We will create matrices using matrix() function in R programming. Another function that will be used is unlist() function to convert the lists into a vector.

lst1 <- list(list(1, 2, 3),             list(4, 5, 6))  cat("The list is:\n") print(lst1) cat("Class:", class(lst1), "\n")  mat <- matrix(unlist(lst1), nrow = 2, byrow = TRUE)  cat("\nAfter conversion to matrix:\n") print(mat) cat("Class:", class(mat), "\n")

Output

The list is: [[1]] [[1]][[1]] [1] 1  [[1]][[2]] [1] 2  [[1]][[3]] [1] 3   [[2]] [[2]][[1]] [1] 4  [[2]][[2]] [1] 5  [[2]][[3]] [1] 6   Class: list   After conversion to matrix:      [,1] [,2] [,3] [1,...

In this article we have covered Lists in R, we have covered list operations like creating, naming, merging and deleting a list in R language.

Also Check:
R-Array
R- Tuples
R - Matrices

R - Array

AmiyaRanjanRout

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Article Tags :

R-Lists

1. Creating a List

2. Naming List Components

3. Accessing R List Components

3.1. Access components by names:

3.2. Access components by indices:

4. Modifying Components of a List

5. Concatenation of lists

6. Adding Item to List

7. Deleting Components of a List

8. Merging list

9. Converting List to Vector

10. R List to matrix

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