How to Change Legend Title in Ggplot

How to change legend title in ggplot

This should work:

p <- ggplot(df, aes(x=rating, fill=cond)) + 
           geom_density(alpha=.3) + 
           xlab("NEW RATING TITLE") + 
           ylab("NEW DENSITY TITLE")
p <- p + guides(fill=guide_legend(title="New Legend Title"))

(or alternatively)

p + scale_fill_discrete(name = "New Legend Title")

Changing legend title in ggplot changes the shown legend aesthetic

You need guide_colourbar instead of guide_legend

ggplot(df, aes(x, y, col = col)) +
  geom_point() +
  guides(col = guide_colourbar(title = "Some title"))

Though personally, I would normally just change the label of the color aesthetic:

ggplot(df, aes(x, y, col = col)) +
  geom_point() +
  labs(color = "Some title")

Which gives the same result with fewer keystrokes.

Change legend title ggplot2

You can try with this:

ggplot(data = descripintens
       ,aes(x = syear, y = workingintensity, group = treatment,colour = factor(treatment))) +
  geom_line() +
  xlab("Year") +
  ylab("Working intensity") + 
  labs(color='NEW LEGEND TITLE')  +
  # you should specify the color also
  scale_color_manual(labels = c("Control", "Treatment")
                     ,values = c("blue", "red"))

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With data:

descripintens <- read.table(text ="   syear treatment workingintensity
1  2014     0         96.2
2  2014     1         98.4
3  2015     0         101.00000
4  2015     1         102.00000
5  2016     0         105.9
6  2016     1         106.2")

How can I change legend labels in ggplot?

You can do that via the labels= argument in a scale_color_*() function by supplying a named vector. Here's an example:

library(ggplot2)

set.seed(1235)
df <- data.frame(x=1:10, y=1:10, z = sample(c("Control", "B", "C"), size=10, replace=TRUE))

df$z <- factor(df$z, levels=c("Control", "B", "C"))  # setting level order

p <- ggplot(df, aes(x,y, color=z)) + geom_point(size=4)
p

To change the name of "Control" totally "in plot code", I'll use scale_color_hue(labels=...). Note that by default, ggplot2 uses an evenly-spaced hue scaling, so this keeps the colors themselves the same. Using a named vector is not required, but a good idea to ensure you don't have mixing up of names/labels:

p + scale_color_hue(labels=c("Control" = "A", "B"="B", "C"="C"))

How can I change the title of a ggplot2 legend?

Add

+ labs(colour = "legend title") 

to your ggplot call.
Great resource site is also google group for ggplot2.

edit: this assumes that colour is the aesthetic in the legend, e.g. qplot(x,y,colour=z). If another aesthetic is being shown in the legend, use that as the argument instead, e.g. + labs(fill = "legend title") for a raster/image plot.

More generally, if you specify an explicit scale such as scale_colour_continuous, you can set the scale_name argument (warning: the details of the arguments to scales may have changed in recent releases of ggplot2; this description is of version 0.9.2.1).

Legend title in ggplot2

You can rename aesthetics in legends for example via the ggplot2 function labs like in the following reprex.

library(ggplot2)

df <- data.frame(
  x = runif(100),
  y = runif(100),
  z1 = rnorm(100),
  z2 = abs(rnorm(100))
)

ggplot(df, aes(x, y)) +
  geom_point(aes(colour = z1)) +
  scale_colour_gradient2() +
  labs(colour = "My Legend Name")

reprex output

^{Created on 2021-10-13 by the reprex package (v2.0.1)}

Legend Titles with two Lines

Have you tried to manually fill the aesthetics color with the value that you want?

See the section 11.7 of Wickham's book ggplot2: elegant graphics for data analysis. By the way, this book is amazing!

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