R語言與醫學統計圖形-【14】ggplot2幾何對象之直方密度圖

ggplot2繪圖系統——幾何對象之直方圖、密度圖

1.直方圖

參數。

geom_histogram(mapping = ,
               data = ,
               stat = 'bin', #統計變換，概率密度為density
               position = 'stack',
               binwidth = , #條柱寬度
               bins = , #條柱數目，默認30
               na.rm = FALSE,
               show.legend = NA,
               inherit.aes = TRUE
               )

示例。

ggplot(diamonds,aes(carat))+
  geom_histogram(fill='darkorchid4')

ggplot(diamonds,aes(carat))+
  geom_histogram(fill='darkorchid4',bins=45)+
  xlim(0,3)

# bins和binwidth
ggplot(diamonds,aes(carat))+
  geom_histogram(fill='darkorchid4',bins = 300)

ggplot(diamonds,aes(carat))+
  geom_histogram(fill='darkorchid4',binwidth = 0.01)
#binwidth參數是一個相對寬度

#顏色映射
ggplot(diamonds,aes(price,fill=cut))+
  geom_histogram(binwidth = 500)

2.概率密度曲線

三種方法：

#stat=density
ggplot(diamonds,aes(price))+
  geom_histogram(color='darkorchid4',stat='density')

#aes映射，..density..表示將y軸表示為density
ggplot(diamonds,aes(price, ..density..))+
  geom_histogram(fill='darkorchid4',color='black')

#geom_density
ggplot(diamonds,aes(depth,fill=cut,color=cut))+
  geom_density(alpha=0.1)+xlim(55,70)