R ggplot2 Histogram with Overlaying Normal Density Curve (Example Code)
In this R tutorial you’ll learn how to overlay a normal density line on top of a ggplot2 histogram.
Setting up the Example
data(iris) # Loading example data head(iris) # Sepal.Length Sepal.Width Petal.Length Petal.Width Species # 1 5.1 3.5 1.4 0.2 setosa # 2 4.9 3.0 1.4 0.2 setosa # 3 4.7 3.2 1.3 0.2 setosa # 4 4.6 3.1 1.5 0.2 setosa # 5 5.0 3.6 1.4 0.2 setosa # 6 5.4 3.9 1.7 0.4 setosa |
data(iris) # Loading example data head(iris) # Sepal.Length Sepal.Width Petal.Length Petal.Width Species # 1 5.1 3.5 1.4 0.2 setosa # 2 4.9 3.0 1.4 0.2 setosa # 3 4.7 3.2 1.3 0.2 setosa # 4 4.6 3.1 1.5 0.2 setosa # 5 5.0 3.6 1.4 0.2 setosa # 6 5.4 3.9 1.7 0.4 setosa
install.packages("ggplot2") # Install ggplot2 package library("ggplot2") # Load ggplot2 package |
install.packages("ggplot2") # Install ggplot2 package library("ggplot2") # Load ggplot2 package
ggplot(iris, aes(x = Sepal.Length)) + # Default histogram without normal curve geom_histogram() |
ggplot(iris, aes(x = Sepal.Length)) + # Default histogram without normal curve geom_histogram()
Example: Overlaying Normal Density Curve on Top of ggplot2 Histogram in R
ggplot(iris, aes(x = Sepal.Length)) + # Adding normal curve to histogram geom_histogram(aes(y = ..density..)) + stat_function(fun = dnorm, args = list(mean = mean(iris$Sepal.Length), sd = sd(iris$Sepal.Length)), col = "red", size = 3) |
ggplot(iris, aes(x = Sepal.Length)) + # Adding normal curve to histogram geom_histogram(aes(y = ..density..)) + stat_function(fun = dnorm, args = list(mean = mean(iris$Sepal.Length), sd = sd(iris$Sepal.Length)), col = "red", size = 3)