Table of Contents
To display percentages on a histogram in ggplot2, first create a data frame containing the data to be plotted, then use the geom_histogram() function to create the histogram. Then use the geom_text() function to add the percentages as labels on the bars of the histogram. Use the nudge_x argument in the geom_text() function to adjust the position of the labels so that they are centered on the bars.
You can use the following basic syntax to display percentages on the y-axis of a histogram in ggplot2:
library(ggplot2) library(scales) #create histogram with percentages ggplot(data, aes(x = factor(team))) + geom_bar(aes(y = (..count..)/sum(..count..))) + scale_y_continuous(labels=percent)
The following examples show how to use this syntax in practice.
Example 1: Basic Histogram with Percentages
The following code shows how to create a histogram for categorical variables with percentages displayed on the y-axis:
library(ggplot2) library(scales) #define data frame data <- data.frame(team = c('A', 'A', 'A', 'A', 'B', 'B', 'B', 'C', 'C', 'C', 'C'), points = c(77, 79, 93, 85, 89, 99, 90, 80, 68, 91, 92)) #create histogram with percentages ggplot(data, aes(x = factor(team))) + geom_bar(aes(y = (..count..)/sum(..count..))) + scale_y_continuous(labels=percent)
Example 2: Histogram with Percentages (Remove Decimal Places)
You can use the accuracy argument to only display whole numbers as percentages on the y-axis as well:
library(ggplot2) library(scales) #define data frame data <- data.frame(team = c('A', 'A', 'A', 'A', 'B', 'B', 'B', 'C', 'C', 'C', 'C'), points = c(77, 79, 93, 85, 89, 99, 90, 80, 68, 91, 92)) #create histogram with percentages ggplot(data, aes(x = factor(team))) + geom_bar(aes(y = (..count..)/sum(..count..))) + scale_y_continuous(labels = scales::percent_format(accuracy = 1L))
Example 3: Custom Histogram with Percentages
The following code shows how to create a histogram with percentages shown on the y-axis and a custom title, axis labels, and colors:
library(ggplot2) library(scales) #define data frame data <- data.frame(team = c('A', 'A', 'A', 'A', 'B', 'B', 'B', 'C', 'C', 'C', 'C'), points = c(77, 79, 93, 85, 89, 99, 90, 80, 68, 91, 92)) #create histogram with percentages and custom aesthetics ggplot(data, aes(x = factor(team))) + geom_bar(aes(y = (..count..)/sum(..count..)), fill = 'lightblue') + scale_y_continuous(labels=percent) + labs(title = 'Breakdown by Team', x = 'Team', y = 'Percent of Total') + theme_minimal()
Related: