How To Make a Bar Plot in R

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DataDaft

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54,100

Published on October 14, 2019 7:55:15 PM ● Video Link: https://www.youtube.com/watch?v=XBqnL2RUVcg

Category:

Guide

Duration: 3:14

37,761 views

261

Bar plots let you view categorical variables as bars with heights based on the count of records within each category or some other summary value.


Code used in this clip:

# Load ggplot2 and data
library(tidyverse)

data ＜- mtcars
data$cyl ＜- as.factor(data$cyl)

# Bar plot in base R
barplot( table(data$cyl) )

# Bar plot in ggplot2
data %＞% ggplot(aes(x = cyl)) +
geom_bar()

# Bar plot with swapped axes
data %＞% ggplot(aes(x = cyl)) +
geom_bar(aes(fill = cyl)) +
coord_flip()

# Create a summary table of avg mpg by cylindar
table2 ＜- data %＞% group_by(cyl) %＞%
summarize(avg_mpg = mean(mpg))

table2

# Bar plot with bar height set to a summary value
table2 %＞% ggplot(aes(x = cyl, y = avg_mpg)) +
geom_bar(aes(fill = cyl))

Code Clips are basic code explanations in 3 minutes or less. They are intended to be short reference guides that provide quick breakdowns and copy/paste access to code needed to accomplish common data science tasks. Think Stack Overflow with a video explanation.


* Note: YouTube does not allow greater than or less than symbols in the text description, so the code above may not be exactly the same as the code shown in the video! For R that means I may use = for assignment and the special Unicode large ＜ and ＞ symbols in place of the standard sized ones for dplyr pipes and comparisons. These special symbols should work as expected for R code on Windows, but may need to be replaced with standard greater than and less than symbols for other operating systems.