You can use the rnorm() and runif() functions to generate random values in R.
Here’s the difference between the two functions:
The rnorm(n, mean, sd) function is used to generate n random values from a normal distribution with a specific mean and standard deviation.
The runif(n, min, max) function is used to generate n random values from a uniform distribution with a specific minimum and maximum value.
The following examples show how to use each function in practice.
Example 1: How to Use rnorm() in R
The following code shows how to use the rnorm() function to generate 100 random values from a normal distribution with a mean of 10 and a standard deviation of 2:
#make this example reproducible
set.seed(0)
#create vector of 100 random values from normal distribution
random_values <- rnorm(n=100, mean=10, sd=2)
#view first six values
head(random_values)
[1] 12.525909 9.347533 12.659599 12.544859 10.829283 6.920100
We can also use the hist() function to create a histogram to visualize the distribution of random values we just generated:
#create histogram to visualize distribution of values
hist(random_values)
The result is a histogram that displays the distribution of the 100 values from the normal distribution.
Notice that the histogram has a bell shape and the mean is located around 10, the exact value that we specified for the mean of the distribution.
Example 2: How to Use runif() in R
The following code shows how to use the runif() function to generate 100 random values from a uniform distribution with a minimum value of 5 and a maximum value of 25:
#make this example reproducible
set.seed(0)
#create vector of 100 random values from uniform distribution
random_values <- runif(n=100, min=5, max=25)
#view first six values
head(random_values)
[1] 22.933944 10.310173 12.442478 16.457067 23.164156 9.033639
We can also use the hist() function to create a histogram to visualize the distribution of random values we just generated:
#create histogram to visualize distribution of values
hist(random_values)
The result is a histogram that displays the distribution of the 100 values from the uniform distribution.
Notice that the histogram ranges from 5 to 25, which represent the minimum and maximum values that we specified in the runif() function.
Additional Resources
The following tutorials explain how to perform other common tasks in R:
How to Plot a Uniform Distribution in R
How to Plot a Normal Distribution in R
How to Select Random Samples in R
