Remove extra legends in ggplot2

user_173292 0
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I have a simple data frame that I'm trying to do a combined line and point plot using ggplot2. Supposing my data looks like this:

df <- data.frame(x=rep(1:10,2), y=c(1:10,11:20), 
                 group=c(rep("a",10),rep("b",10)))

And I'm trying to make a plot:

g <- ggplot(df, aes(x=x, y=y, group=group))
g <- g + geom_line(aes(colour=group))
g <- g + geom_point(aes(colour=group, alpha = .8))
g

The result looks fine with one exception. It has an extra legend showing the alpha for my geom_point layer.

Extra Legend for <code>geom_point</code> transparency

How can I keep the legend showing group colors, but not the one that shows my alpha settings?

ggplot2 legend r
4 Answers

Another simple option is using the function guides, which makes it possible to remove a particular aesthetic (fill, alpha, color) or multiple from the legend. Here is a reproducible example for removing only alpha legend and removing both alpha and color:

df <- data.frame(x=rep(1:10,2), y=c(1:10,11:20), 
                 group=c(rep("a",10),rep("b",10)))
library(ggplot2)
g <- ggplot(df, aes(x=x, y=y, group=group))
g <- g + geom_line(aes(colour=group))
g <- g + geom_point(aes(colour=group, alpha = .8))
# Remove legend alpha
g + guides(alpha = "none")


# Remove legend alpha and color
g + guides(alpha = "none", color = "none")

Created on 2022-08-21 with reprex v2.0.2

user_142827140
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