3.Histogram plots

3.1 Basic histogram plot

head(df2)

##   sex weight
## 1   F     49
## 2   F     56
## 3   F     60
## 4   F     43
## 5   F     57
## 6   F     58

ggplot(df2, aes(x=weight)) + geom_histogram(binwidth=1)

3.2 Add mean line on a histogram plot

ggplot(df2, aes(x=weight)) + 
  geom_histogram(binwidth=1, color="black", fill="white") +
  geom_vline(aes(xintercept=mean(weight)),color="black", linetype="dashed", size=0.5)

3.3 Change histogram plot fill colors

#Use the plyr package to calculate the average weight of each group :
mu <- ddply(df2, "sex", summarise, grp.mean=mean(weight))
head(mu)

##   sex grp.mean
## 1   F    54.70
## 2   M    65.36

#draw the plot
ggplot(df2, aes(x=weight, color=sex)) +
  geom_histogram(binwidth=1, fill="white", position="dodge")+
  geom_vline(data=mu, aes(xintercept=grp.mean, color=sex), linetype="dashed") +
  scale_color_brewer(palette="Paired") + 
  theme_classic()+
  theme(legend.position="top")

Reference: http://www.sthda.com/english/wiki/ggplot2-histogram-plot-quick-start-guide-r-software-and-data-visualization