library(dplyr)

iris

iris %>%
 group_by(Species) %>%
 summarise(Sepal.Width.Avg = mean(Sepal.Width)) %>%
 arrange(Sepal.Width.Avg)

library(ggplot2)

ggplot(data=iris, aes(x=Sepal.Length, y=Sepal.Width, color=Species)) + geom_point(size=3)