# Sum a List of Matrices in R (Example)

In this article, I’ll show how to **calculate the sum of all matrix objects in a list** in the R programming language.

The tutorial contains these contents:

Let’s dive into it!

## Creation of Example Data

Have a look at the following example data:

my_list <- list(mat1 = matrix(1:16, ncol = 4), # Create example list of matrices mat2 = matrix(11:26, ncol = 4), mat3 = matrix(101:116, ncol = 4)) my_list # Print example list of matrices # $mat1 # [,1] [,2] [,3] [,4] # [1,] 1 5 9 13 # [2,] 2 6 10 14 # [3,] 3 7 11 15 # [4,] 4 8 12 16 # # $mat2 # [,1] [,2] [,3] [,4] # [1,] 11 15 19 23 # [2,] 12 16 20 24 # [3,] 13 17 21 25 # [4,] 14 18 22 26 # # $mat3 # [,1] [,2] [,3] [,4] # [1,] 101 105 109 113 # [2,] 102 106 110 114 # [3,] 103 107 111 115 # [4,] 104 108 112 116 |

my_list <- list(mat1 = matrix(1:16, ncol = 4), # Create example list of matrices mat2 = matrix(11:26, ncol = 4), mat3 = matrix(101:116, ncol = 4)) my_list # Print example list of matrices # $mat1 # [,1] [,2] [,3] [,4] # [1,] 1 5 9 13 # [2,] 2 6 10 14 # [3,] 3 7 11 15 # [4,] 4 8 12 16 # # $mat2 # [,1] [,2] [,3] [,4] # [1,] 11 15 19 23 # [2,] 12 16 20 24 # [3,] 13 17 21 25 # [4,] 14 18 22 26 # # $mat3 # [,1] [,2] [,3] [,4] # [1,] 101 105 109 113 # [2,] 102 106 110 114 # [3,] 103 107 111 115 # [4,] 104 108 112 116

The previous RStudio console output shows that our example data is a list object containing three different matrices.

## Example: Get Sum of All Matrices in List Using Reduce() Function

The following R code explains how to add the values in multiple matrices in a list.

For this task, we can apply the Reduce function as shown below:

list_sum <- Reduce("+", my_list) # Calculate sum of matrices list_sum # Print sum of matrices |

list_sum <- Reduce("+", my_list) # Calculate sum of matrices list_sum # Print sum of matrices

Have a look at the previous table: It shows the sum of the three matrices in our example list stored in a new matrix object called list_sum.

## Video & Further Resources

In case you need further information on the R programming codes of this tutorial, I recommend having a look at the following video on my YouTube channel. In the video, I’m explaining the topics of this tutorial.

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Furthermore, you might want to read the other articles on this website.

To summarize: You have learned in this article how to **compute the sum of all matrices in a list** in the R programming language. If you have additional questions, please let me know in the comments section.

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