opalfruits opalfruits -4 years ago 156
R Question

Difficulty annotating plot when x axis values are dates

Here is my data frame:

> s
Date Average Treatment SE
1 2014-10-15 4.875 1 1.6304852
2 2014-11-12 6.250 1 0.9955257
3 2014-12-11 0.250 1 0.1636634
4 2015-02-11 1.000 1 0.5000000
5 2015-03-09 0.000 1 0.0000000
6 2014-10-15 22.750 2 3.4369318
7 2014-11-12 10.625 2 2.1207942
8 2014-12-11 7.500 2 2.9215945
9 2015-02-11 7.750 2 2.3126207
10 2015-03-09 0.125 2 0.1250000


I am producing a plot using this code:

s$Date <- as.Date(s$Date)
s$Treatment <- factor(s$Treatment)
cols <- c("#000000","#F5F5DC")
library(ggplot2)
solitaryrecruits <- (ggplot(s, aes(x=Date, y=Average, fill=Treatment)) +
geom_bar(width=20, position=position_dodge(20),
stat="identity", colour="black") +
geom_errorbar(aes(ymin=Average, ymax=Average+SE),
width=10,
position=position_dodge(20))+
scale_fill_manual(name="Treatment", labels=c("No Cage", "Cage"), values = cols) +
labs(x=("Panel Date"), y=expression(bold(paste("Mean Num. Ind. ( " ,cm^2, ")", sep = "")))) +
theme_bw() +
theme(axis.text=element_text(size=14),
legend.title=element_text(size=14),
legend.text=element_text(size=12),
axis.title=element_text(size=16,face="bold"),
legend.justification = c(1, 1), legend.position = c(1, 1),
axis.title.x = element_text(vjust=-0.2),
axis.title.y = element_text(vjust=+0.6))) +
guides(fill = guide_legend(override.aes = list(colour = NULL))) +
theme(legend.key = element_rect(colour = "black"))


enter image description here

I have several plots that I am going to present alongside each other. Therefore, I am trying to annotate each plot by placing the text (for this plot "a)") in the top left corner. I have tried to create an annotation layer but I am struggling to specify an x position. Any assistance would be greatly appreciated, thanks!

Edit: here is a manually edited photo to show what I want to place onto the plot:

enter image description here

Answer Source

You can use annotate to reach your goal:

solitaryrecruits +
    annotate(geom="text",x=as.Date("2014-10-05"),
    y=25,label="a",fontface="bold")

The important point is that you give your x-coordinate as a date.

Alternatively, you could label your plots by giving them a title

solitaryrecruits + labs(title="a")
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