Area chart in ggplot2 with geom_area

Sample data set

Consider the following data frame that contains the price of three european stock indices.

df <- as.data.frame(EuStockMarkets[, 1:3])

Area chart of a single line

In order to create an area chart with a column of the input data frame you can pass the dates (if available) or an index to x and the variable of interest to y and then use geom_area.

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

# Area chart
ggplot(df, aes(x = seq_along(SMI), y = SMI)) + 
  geom_area()

Basic area chart in ggplot2

Fill the area

By default the area will be filled with a very dark gray color. However, you can change it passing a color to the fill argument.

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

# Area chart
ggplot(df, aes(x = seq_along(SMI), y = SMI)) + 
  geom_area(fill = 4)

Area plot fill color in ggplot2

Transparency of the area

You can also change the transparency of the area with the alpha argument of the function.

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

# Area chart
ggplot(df, aes(x = seq_along(SMI), y = SMI)) + 
  geom_area(fill = 4,
            alpha = 0.5)

Transparency of the area in ggplot2

Line customization

The upper line of the area can be customized with several arguments, such as color, lwd or linetype.

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

# Area chart
ggplot(df, aes(x = seq_along(SMI), y = SMI)) + 
  geom_area(fill = 4,
            alpha = 0.5,
            color = 1,    # Line color
            lwd = 0.5,    # Line width
            linetype = 1) # Line type

ggplot2 area plot border customization

Area chart of several lines

Area chart of several variables in ggplot2

In case you want to add more variables you will need to specify the aesthetics inside each geom_area for each variable. Note that if the number of areas to add is more than two or three you should consider creating a stacked area chart.

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

# Area chart
ggplot(df) + 
  geom_area(aes(x = seq_along(SMI), y = SMI),
            fill = 4, alpha = 0.85) +
  geom_area(aes(x = seq_along(DAX), y = DAX),
            fill = 3, alpha = 0.85)
ggplot2

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See also