錯誤製作一個簡單的箱線時GGPLOT2

Question

使用R中的MPG數據，我可以讓「顯示終端」的箱線與

boxplot(mpg$displ) 

但是，當我試圖讓與ggplot這個簡單的箱線圖，

ggplot(data = mpg, aes(displ)) + geom_boxplot() 

我得到這個錯誤;

Error in seq.default(from = best$lmin, to = best$lmax, by = best$lstep) : 'from' must be of length 1 
In addition: Warning messages: 
1: Continuous x aesthetic -- did you forget aes(group=...)? 
2: In is.na(data$y) : is.na() applied to non-(list or vector) of type 'NULL' 

Answer 1

ggplot2既需要的箱線圖的x和y變量。以下是如何製作單個箱型圖

ggplot(data = mpg, aes(x = "", y = displ)) + 
    geom_boxplot() + 
    theme(axis.title.x = element_blank())