I wish to change the title and labels of a legend in geom_col plot in ggplot2.
I have tried to use the functions below to change the legend title, however nothing happens:
labs(color = "Treatment")
labs(fill = "Treatment")
I have also tried to use to change legend title and labels:
scale_fill_discrete(name = "Treatment", labels = c("Control",
"Fertilization", "Shading", "Warming))
However then the plot column changes color and I receive the following error message:
Scale for 'fill' is already present. Adding another scale for 'fill', which will replace the existing scale.
My code looks like this:
bar.plot.selected.groups <- ggplot(mean_emission_p12_gr3, aes (x = date, y =
avg_emission, fill = Treatment)) + geom_errorbar(aes(ymin = avg_emission -
se, ymax = avg_emission + se), width = 0.5, position = position_dodge(width
= 0.65)) + geom_col (position = "dodge", width=0.65) + theme(axis.text.x =
element_text(size = 10, angle = 90, hjust=0, vjust = 0.5), axis.title =
element_text(size = 14))
bar.plot.selected.groups + labs(x = "Date", y = "Emission rate (µg m-2 h-
1)", color = treatment) + ggtitle("BVOC emission 2012") + theme(plot.title =
element_text(size = 20, hjust = 0.5)) + facet_wrap(~ compound_gr_3, scales =
"free") + theme(strip.text.x = element_text(size = 12, color = "black",
face = "bold")) + scale_fill_manual("legend", values = c("C" = "black", "F"
= "green", "S" = "blue", "W" = "red"))
