using the data set airquality I have written the following code:
library("tidyverse")
data(airquality)
airquality <- na.omit(airquality)
airquality$date <- as.Date(paste("1973", airquality$Month, airquality$Day,
sep="-"))
p1 <- ggplot(airquality, aes(x= date, y = Ozone, col=factor(Month))) +
geom_point() +
geom_line()
p1
Now I would like to plot in the same graph the mean of ozone for each months. How can I do this?
You could add the mean as a dashed line. The easiest way to do this might be to simply pass the data you want to a geom_line layer:
ggplot(airquality, aes(x = date, y = Ozone, col = factor(Month))) +
geom_point() +
geom_line(alpha = 0.5) +
geom_line(data = airquality %>%
group_by(Month) %>%
summarise(Ozone = mean(Ozone),
date = c(first(date), last(date)),
Month = mean(Month)),
linetype = 2, size = 1) +
scale_color_brewer(palette = "Set1") +
theme_minimal(base_size = 16)
If you just want points showing the mean, you could simplify things with stat_mean from ggpubr
ggplot(airquality, aes(x = date, y = Ozone, col = factor(Month))) +
geom_point() +
geom_line(alpha = 0.5) +
ggpubr::stat_mean(size = 5, shape = 21,
aes(fill = factor(Month)), color = "black") +
scale_color_brewer(palette = "Set1") +
scale_fill_brewer(palette = "Set1") +
theme_minimal(base_size = 16)
To join these dots up, you could do:
ggplot(airquality, aes(x = date, y = Ozone, col = factor(Month))) +
geom_point() +
geom_line(alpha = 0.5) +
geom_line(data = airquality %>%
group_by(Month) %>%
summarise(Ozone = mean(Ozone), date = mean(date)),
color = "black", linetype = 2) +
ggpubr::stat_mean(size = 5, shape = 21,
aes(fill = factor(Month)), color = "black") +
scale_color_brewer(palette = "Set1") +
scale_fill_brewer(palette = "Set1") +
theme_minimal(base_size = 16)
