Packages

For this post, we need to load the following libraries:

library(ggplot2)
library(ggpattern)
library(hrbrthemes)

Dataset

We create a simple dataset with 2 columns, randomly generated thanks to runif() and rnorm() functions.

set.seed(0)
n = 10
x = 1:n
y = x + rnorm(n=n, mean=100, sd=20)
df = data.frame(xValue = x,
                yValue = y)

Most basic area chart

To create an area chart with R, all we need to do is add the geom_area() function from ggplot2.

ggplot(df, aes(x=xValue, y=yValue)) +
  geom_area(colour='black', fill='lightblue')

Add a simple gradient color

To add a color gradient in place of the light blue, we need to use the ggpattern library and define which colors will be used for the graph.

The bottom color is white and the top color is red.

ggplot(df, aes(xValue, yValue)) + 
  geom_area_pattern(data = df,
                    pattern = "gradient",
                    pattern_fill = "white",
                    pattern_fill2 = "red")

Gradient color with transparency

To add transparency to the graphic, simply use colors that are naturally transparent. For example, here we change white to transparent grey.

The bottom color is a transpaent light grey (#00000010) and the top color is blue.

ggplot(df, aes(xValue, yValue)) + 
  geom_area_pattern(data = df,
                    pattern = "gradient",
                    fill = "#00000010",
                    pattern_fill  = "#00000010",
                    pattern_fill2 = "blue")

Fully customized area chart wiht gradient

If we take what we’ve seen above and add other features like changing the theme, removing axis lines etc., you end up with an even more beautiful graph.

In this case, we: - add a black line for the upper part of the area chart - change the theme with the hrbrthemes library - remove axis lines

ggplot(df, aes(xValue, yValue)) + 
  geom_area_pattern(data = df,
                    pattern = "gradient", 
                    fill = "#00000000",
                    pattern_fill  = "#00000000",
                    pattern_fill2 = "magenta") + 
  geom_line(data = df, colour = "black", linewidth = 0.8) +
  geom_point(shape = 16, size = 4.5, colour = "purple") +
  geom_point(shape = 16, size = 2.5, colour = "white") +
  ggtitle("Area chart with a color gradient and line with data points") + 
  theme_bw() +
  theme(plot.title = element_text(size = 14),
        panel.border       = element_blank(),
        axis.line.x        = element_line(),
        text               = element_text(size = 12),
        axis.ticks         = element_blank(),
        axis.text.y        = element_text(margin = margin(0,15,0,0, unit = "pt"))) +
  scale_alpha_identity() + labs(x="",y="")

Conclusion

This post explained how to add a color gradient to an area chart using the ggpattern library. For more area chart examples, see the dedicated section.

Related chart types

Line plot

Area

Stacked area

Streamchart

Time Series

Contact

This document is a work by Yan Holtz. Any feedback is highly encouraged. You can fill an issue on Github, drop me a message on Twitter, or send an email pasting yan.holtz.data with gmail.com.

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