R How to Change Line Color & Type in Legend of ggplot2 Plot (Example Code)

On this page you’ll learn how to adjust line colors and types of a ggplot2 legend of a line chart in the R programming language.

Setting up the Example

data(iris)                                   # Load iris
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
my_plot <- ggplot(iris, aes(Petal.Length,    # Drawing graph with ggplot2 package
                            Petal.Width,
                            color = Species,
                            linetype = Species)) +
  geom_line()
my_plot

r graph figure 1 r change line color type legend ggplot2 plot

Example: Modifying Lines and Colors of ggplot2 Legend

my_plot +                                    # Adjusting linetypes & colors
  scale_linetype_manual(values = c("twodash", "solid", "dashed")) +
  scale_color_manual(values = c("green", "red", "purple"))

r graph figure 2 r change line color type legend ggplot2 plot

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