[R] How to customize legend labels in ggplot2?

[Luigi Marongiu]

Thank you, that is exactly was I was looking for.

On Thu, Mar 13, 2025 at 8:16 AM Rui Barradas <ruipbarradas using sapo.pt> wrote:
>
> Hello,
>
> Inline.
>
> Às 05:19 de 13/03/2025, Luigi Marongiu escreveu:
> > Thank you, but then I will have long labels also on the axis,
>
>
> I am not getting the same legend labels and axis labels, only the legend
> is labelled as variable lbls, the axis labels are numeric.
> I am running the following reproducible example.
>
>
> library(ggplot2)
>
> lbls <- c("Condition 1", "Condition 2", "Condition 3", "Control")
> COLS <- 1:4
>
> df = data.frame(Target = 1:4,
>                  Rate = c(0.02078663, 0.03685543, 0.02238002, 0.05033979),
>                  SD = c(0.003043398, 0.001447410, 0.002998729, 0.002171813))
>
> df$Target = factor(df$Target)
>
> ggplot(df, aes(x = Target, y = Rate, colour = Target, group = Target)) +
>    geom_point(size = 8) +
>    geom_errorbar(aes(ymin = Rate - SD, ymax = Rate + SD), width = 0.1) +
>    # this is the only thing different from your original code
>    scale_colour_manual(values = COLS, labels = lbls) +
>    xlab(expression(bold("Class"))) +
>    ylab(expression(bold("Value"))) +
>    theme_classic(base_size = 15)
>
>
> What code are you running? The OP code?
>
> Hope this helps,
>
> Rui Barradas
>
> making the
> > plot too crowded. I would like instead to force the long labels only on the
> > legend...
> >
> > On Wed, 12 Mar 2025, 12:47 Rui Barradas, <ruipbarradas using sapo.pt> wrote:
> >
> >> Às 10:35 de 12/03/2025, Luigi Marongiu escreveu:
> >>> I have a data frame with measurements in different conditions. I set
> >>> the conditions as a factor using a notation for ease of use. I now
> >>> want to plot the data and assign meaningful labels to the factors. I
> >>> am using ggplot2; for the x axis I would like to keep the factors but
> >>> in the legend I would like to use custom values.
> >>> I tried different combinations but none worked.
> >>> What is the correct way to assign
> >>> custom labels to legends in ggplot2?
> >>> Thank you
> >>>
> >>> EXAMPLE:
> >>> ```
> >>> df = data.frame(Target = 1:4,
> >>>                   Rate = c(0.02078663, 0.03685543, 0.02238002,
> >> 0.05033979),
> >>>                   SD = c(0.003043398, 0.001447410, 0.002998729,
> >> 0.002171813))
> >>> df$Target = factor(df$Target)
> >>> ggplot(df, aes(x=Target, y=Rate, colour=Target, group=Target)) +
> >>>     geom_point(size=8) +
> >>>     geom_errorbar(aes(ymin=Rate-SD, ymax=Rate+SD), width=.1) +
> >>>     scale_colour_manual(values = COLS) +
> >>>     xlab(expression(bold("Class"))) +
> >>>     ylab(expression(bold("Value"))) +
> >>>     theme_classic(base_size = 15)
> >>> ```
> >>> NOTE: if using
> >>> ```
> >>> ...
> >>>     theme_classic(base_size = 15, labels = c("Condition 1", "Condition 2",
> >>>                                              "Condition 3", "Control"))
> >>> ```
> >>> I get the error:
> >>>
> >>> Error in theme_classic(base_size = 15, labels = c("Condition 1",
> >>> "Condition 2",  :
> >>>     unused argument (labels = c("Condition 1", "Condition 2", "Condition
> >>> 3", "Control"))
> >>>
> >>> ______________________________________________
> >>> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> >>> https://stat.ethz.ch/mailman/listinfo/r-help
> >>> PLEASE do read the posting guide
> >> https://www.R-project.org/posting-guide.html
> >>> and provide commented, minimal, self-contained, reproducible code.
> >> Hello,
> >>
> >> The colors COLS are missing from the question.
> >> As for the labels, use
> >>
> >>
> >> lbls <- c("Condition 1", "Condition 2", "Condition 3", "Control")
> >>
> >> and then
> >>
> >> scale_colour_manual(values = COLS, labels = lbls)
> >>
> >>
> >> Hope this helps,
> >>
> >> Rui Barradas
> >>
> >>
> >> --
> >> Este e-mail foi analisado pelo software antivírus AVG para verificar a
> >> presença de vírus.
> >> www.avg.com
> >>
> >
>
>
> --
> Este e-mail foi analisado pelo software antivírus AVG para verificar a presença de vírus.
> www.avg.com



-- 
Best regards,
Luigi