# 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```

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``` 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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