How to Create a Frequency Polygon in R

A frequency polygon is a type of chart that helps you visualize the distribution of values in a dataset.

You can use the following syntax to create a frequency polygon using the ggplot2 data visualization package in R:

library(ggplot2)

ggplot(df, aes(value)) + 
  geom_freqpoly()

The following examples show how to use this syntax in practice.

Example 1: Basic Frequency Polygon

The following code shows how to create a basic frequency polygon for a dataset:

library(ggplot2)

#make this example reproducible
set.seed(0)

#create data frame
df <- data.frame(index=1:100,
                 value=rnorm(100, mean=50, sd=10))

#create frequency polygon
ggplot(df, aes(value)) + 
  geom_freqpoly()

Example 2: Frequency Polygon with Custom Bins

By default, ggplot2 uses 30 bins to create the frequency polygon.

By reducing the number of bins, you can make the lines on the plot smoother. For example, the following code creates a frequency polygon using 10 bins:

library(ggplot2)

#make this example reproducible
set.seed(0)

#create data frame
df <- data.frame(index=1:100,
                 value=rnorm(100, mean=50, sd=10))

#create frequency polygon
ggplot(df, aes(value)) + 
  geom_freqpoly(bins=10)

Frequency polygon with custom bins in R

Example 3: Frequency Polygon with Fill Color

If you’d like to fill in the frequency polygon with a certain color, you’ll need to instead use the geom_area() function as follows:

library(ggplot2)

#make this example reproducible
set.seed(0)

#create data frame
df <- data.frame(index=1:100,
                 value=rnorm(100, mean=50, sd=10))

#create frequency polygon filled with custom color
ggplot(df, aes(value)) + 
  geom_area(aes(y=..count..), bins=10, stat='bin', fill='steelblue')