A **kernel density plot** is a type of plot that displays the distribution of values in a dataset using one continuous curve.

A kernel density plot is similar to a histogram, but it’s even better at displaying the shape of a distribution since it isn’t affected by the number of bins used in the histogram.

We can use the following methods to create a kernel density plot in R:

**Method 1: Create One Kernel Density Plot**

#define kernel density kd <- density(data) #create kernel density plot plot(kd)

**Method 2: Create a Filled-In Kernel Density Plot**

#define kernel density kd <- density(data) #create kernel density plot plot(kd) #fill in kernel density plot with specific color polygon(kd, col='blue', border='black')

**Method 3: Create Multiple Kernel Density Plots**

#plot first kernel density plot kd1 <- density(data1) plot(kd1, col='blue') #plot second kernel density plot kd2 <- density(data2) lines(kd2, col='red') #plot third kernel density plot kd3 <- density(data3) lines(kd3, col='purple') ...

The following examples show how to use each method in practice.

**Method 1: Create One Kernel Density Plot**

The following code shows how to create a kernel density plot for one dataset in R:

#create data data <- c(3, 3, 4, 4, 5, 6, 7, 7, 7, 8, 12, 13, 14, 17, 19, 19) #define kernel density kd <- density(data) #create kernel density plot plot(kd, main='Kernel Density Plot of Data')

The x-axis shows the values of the dataset and the y-axis shows the relative frequency of each value. The highest points in the plot show where the values occur most often.

**Method 2: Create a Filled-In Kernel Density Plot**

The following code shows how to create a kernel density plot with a specific border color and filled-in color:

#create data data <- c(3, 3, 4, 4, 5, 6, 7, 7, 7, 8, 12, 13, 14, 17, 19, 19) #define kernel density kd <- density(data) #create kernel density plot plot(kd) #add color polygon(kd, col='steelblue', border='black')

**Method 3: Create Multiple Kernel Density Plots**

The following code shows how to create multiple kernel density plots in one plot in R:

#create datasets data1 <- c(3, 3, 4, 4, 5, 6, 7, 7, 7, 8, 12, 13, 14, 17, 19, 19) data2 <- c(12, 3, 14, 14, 4, 5, 6, 10, 14, 7, 7, 8, 10, 12, 17, 20) #plot first kernel density plot kd1 <- density(data1) plot(kd1, col='blue', lwd=2) #plot second kernel density plot kd2 <- density(data2) lines(kd2, col='red', lwd=2)

Note that we can use similar syntax to create as many kernel density plots in one chart as we’d like.

**Additional Resources**

The following tutorials explain how to create other common plots in R:

How to Plot Multiple Boxplots in R

How to Plot Multiple Histograms in R

How to Plot Multiple Lines in R