Create Matrix of Lists in R (Example)

In this post, I’ll explain how to construct a matrix of lists in the R programming language.

Table of contents:

You’re here for the answer, so let’s get straight to the example:

Introduction of Example Data

The first step is to create some data that we can use in the examples below:

my_list1 <- list(1, 2, 3)               # Create first list
my_list1                                # Print first list
# [[1]]
# [1] 1
# 
# [[2]]
# [1] 2
# 
# [[3]]
# [1] 3

my_list2 <- list("a", "b", "c", "d")    # Create second list
my_list2                                # Print second list
# [[1]]
# [1] "a"
# 
# [[2]]
# [1] "b"
# 
# [[3]]
# [1] "c"
# 
# [[4]]
# [1] "d"

my_list3 <- list(1, "xxx", 1:3)         # Create third list
my_list3                                # Print third list
# [[1]]
# [1] 1
# 
# [[2]]
# [1] "xxx"
# 
# [[3]]
# [1] 1 2 3

my_list4 <- list(1:3, 2:5)              # Create fourth list
my_list4                                # Print fourth list
# [[1]]
# [1] 1 2 3
# 
# [[2]]
# [1] 2 3 4 5

The previous outputs of the RStudio console show our four exemplifying list objects.

At this point of the tutorial, each of these lists is stored in a different data object.

Example: Combine Lists in Matrix Using matrix() & list() Functions

This example shows how to merge multiple list objects in a single matrix.

Have a look at the following R code and its output:

my_mat <- matrix(list(my_list1,         # Create matrix of lists
                      my_list2,
                      my_list3,
                      my_list4),
                 ncol = 2)
my_mat                                  # Print matrix of lists
#      [,1]   [,2]  
# [1,] list,3 list,3
# [2,] list,4 list,2

As you can see, we have created a 2×2 matrix where each matrix cell contains one of our lists.

Video, Further Resources & Summary

Have a look at the following video on my YouTube channel. In the video, I demonstrate the R code of this page:

Furthermore, you could have a look at the related R posts that I have published on my website.

• Create Matrix that Only Contains Zeros
• Convert Nested Lists to Data Frame or Matrix
• Create Random Matrix in R
• Create Empty Matrix in R
• Introduction to R

In summary: In this R tutorial you have learned how to create a matrix containing list objects. A method that can be useful when you want to create a two-dimensional array of vectors which are of different lengths. Tell me about it in the comments, if you have any additional comments or questions.