Frequency polygons

Graph info

Should I use this graph?

This graph requires:

✅ a numeric (continuous) variable

Description

Frequency polygons are similar to histograms, but they use lines instead of bars to represent the variable’s distribution. The height of the line represents the frequency (or count) of the value occurrence.

When viewing frequency polygons, we’re still assessing the shape of the lines for symmetry and skewness..

Getting set up

Packages

PACKAGES:

Install packages.

Code

install.packages("palmerpenguins")
library(palmerpenguins) 
library(ggplot2)

Data

DATA:

Artwork by @allison_horst

The penguins data

Code

penguins <- palmerpenguins::penguins
glimpse(penguins)

Rows: 344
Columns: 8
$ species           <fct> Adelie, Adelie, Adelie, Adelie, Adelie, Adelie, Adel…
$ island            <fct> Torgersen, Torgersen, Torgersen, Torgersen, Torgerse…
$ bill_length_mm    <dbl> 39.1, 39.5, 40.3, NA, 36.7, 39.3, 38.9, 39.2, 34.1, …
$ bill_depth_mm     <dbl> 18.7, 17.4, 18.0, NA, 19.3, 20.6, 17.8, 19.6, 18.1, …
$ flipper_length_mm <int> 181, 186, 195, NA, 193, 190, 181, 195, 193, 190, 186…
$ body_mass_g       <int> 3750, 3800, 3250, NA, 3450, 3650, 3625, 4675, 3475, …
$ sex               <fct> male, female, female, NA, female, male, female, male…
$ year              <int> 2007, 2007, 2007, 2007, 2007, 2007, 2007, 2007, 2007…

The grammar

Code

CODE:

Create labels with labs()

Initialize the graph with ggplot() and provide data

Map flipper_length_mm to the x axis

Add the geom_freqpoly() layer

Code

labs_freqpoly <- labs(
  title = "Adult foraging penguins",
  subtitle = "Distribution of flipper length",
  x = "Flipper length (millimeters)")
ggp2_freqpoly <- ggplot(data = penguins,
      aes(x = flipper_length_mm)) + 
    geom_freqpoly()
ggp2_freqpoly + 
  labs_freqpoly

Graph

GRAPH:

Experiment to see how many bins fit your variable’s distribution