You can use one of the following methods to create a matrix with random numbers in R:

Method 1: Create Matrix with Random Values in Range

#create matrix of 10 random values between 1 and 20
random_matrix <- matrix(runif(n=10, min=1, max=20), nrow=5)

Method 2: Create Matrix with Random Integers in Range

#create matrix of 10 random integers between 1 and 20
random_matrix <- matrix(round(runif(n=10, min=1, max=20), 0), nrow=5)

The following examples show how to use each of these methods in practice.

Method 1: Create Matrix with Random Values in Range

The following code shows how to create a matrix with 5 rows consisting of 10 random values between 1 and 20:

#make this example reproducible
set.seed(1)

#create matrix with 10 random numbers between 1 and 20
random_matrix <- matrix(runif(n=10, min=1, max=20), nrow=5)

#view matrix
random_matrix

          [,1]      [,2]
[1,]  6.044665 18.069404
[2,]  8.070354 18.948830
[3,] 11.884214 13.555158
[4,] 18.255948 12.953167
[5,]  4.831957  2.173939

The result is a matrix with 5 rows and 2 columns, where each value in the matrix is between 1 and 20.

Method 2: Create Matrix with Random Integers in Range

The following code shows how to create a matrix of 10 random integers between 1 and 50:

#make this example reproducible
set.seed(1)

#create matrix with 10 random integers between 1 and 50
random_matrix <- matrix(round(runif(n=10, min=1, max=50), 0), nrow=5)

#view matrix
random_matrix

     [,1] [,2]
[1,]   14   45
[2,]   19   47
[3,]   29   33
[4,]   46   32
[5,]   11    4

The result is a matrix with 5 rows and 2 columns, where each value in the matrix is an integer between 1 and 50.

Note that the runif() function generates random numbers, including the min and max values.

For example, it’s possible that the matrix above could have included both 1 and 50.

Also note that it’s possible for the same number to appear multiple times in the matrix when using this method.