ggplot2 Delete elements from legend - r

Question

I have this plot:
that was made based on this data:
days variable value sd
1 X1 Control 75.03424 3.857730
2 X2 Control 70.17851 2.913420
3 X3 Control 65.01627 9.188947
4 X4 Control 65.70995 10.882072
5 X5 Control 56.98791 8.070014
6 X6 Control 56.64376 4.827183
7 X1 Stress 75.63113 3.207749
8 X2 Stress 70.56030 5.626266
9 X3 Stress 61.56402 7.078610
10 X4 Stress 48.04541 15.287234
11 X5 Stress 43.54458 8.148382
12 X6 Stress 37.51121 9.494008
With this code:
significance <- data.frame(days=c("X4","X5","X6"),value=c(82,70,67), variable=NA)
# Plot
library(ggplot2)
library(extrafont)
library(scales)
library(Cairo)
ggplot(my_mean, aes(x=days, y=value, fill=variable)) +
geom_bar(stat='identity', position='dodge', width = 0.75) +
geom_errorbar(aes(ymin = value-sd, ymax = value+sd),
position = position_dodge(0.75),
width = 0.3) +
labs(x='\nDAT',y='μg/cm2\n') +
scale_y_continuous(limits = c(0,90), expand = c(0,0),
breaks = seq(from=0,to=90,by=10)) +
scale_x_discrete(labels = c(0,7,14,21,27,35)) +
ggtitle('Chlorophyll Content\n') +
geom_point(data=significance, aes(y=value),shape='*',size=6) +
scale_color_manual(values = c("Control" = 'gray45', "Stress" = 'gray')) +
scale_fill_manual(values = c("Control" = 'gray45', "Stress" = 'gray')) +
theme(panel.border = element_rect(colour = "black", fill=NA, size=0.5),
panel.background = element_rect(fill = 'white'),
plot.title = element_text(hjust = 0.5,family = 'Calibri',face='bold'),
axis.title = element_text(family = 'Calibri',face = 'bold'),
axis.text = element_text(family = 'Calibri'),
legend.text = element_text(family = 'Calibri',face = 'bold'),
legend.position = c(0.92, 0.91),
legend.key = element_rect(fill = NA,color = NA),
legend.title = element_blank(),
legend.background = element_blank()
)
Note how I made a dataframe to map my significance points in the plot. But for some reason, these points also were added to the legend, and don't want this to happens. I suspect this could be fixed with some legend function inside the theme configurations, but I wasn't able to find which function to use and what arguments does it would have.
Any suggestion? Or maybe a better approach to map my significance "stars"?

Answer 1

If you don't want the stars to appear in the legend, try geom_point(..., show.legend = F). In fact, show.legend = F is an option in many ggplot2 layers.

Answer 2

You can try this:
ggplot(my_mean, aes(x=days, y=value, fill=variable)) +
geom_bar(stat='identity', position='dodge', width = 0.75) +
geom_errorbar(aes(ymin = value-sd, ymax = value+sd),
position = position_dodge(0.75),
width = 0.3,color='black') +
labs(x='\nDAT',y='μg/cm2\n') +
scale_y_continuous(limits = c(0,90), expand = c(0,0),
breaks = seq(from=0,to=90,by=10)) +
scale_x_discrete(labels = c(0,7,14,21,27,35)) +
ggtitle('Chlorophyll Content\n') +
geom_point(data=significance, aes(y=value),shape='*',size=6,color='black') +
scale_color_manual(values = c("Control" = 'gray45', "Stress" = 'gray')) +
scale_fill_manual(values = c("Control" = 'gray45', "Stress" = 'gray')) +
guides(fill=guide_legend(override.aes=list(shape=NA)))+
theme(panel.border = element_rect(colour = "black", fill=NA, size=0.5),
panel.background = element_rect(fill = 'white'),
plot.title = element_text(hjust = 0.5,family = 'Calibri',face='bold'),
axis.title = element_text(family = 'Calibri',face = 'bold'),
axis.text = element_text(family = 'Calibri'),
legend.text = element_text(family = 'Calibri',face = 'bold'),
legend.position = c(0.92, 0.91),
legend.key = element_rect(fill = NA,color = NA),
legend.title = element_blank(),
legend.background = element_blank()
)