使用列表排序ggplot x轴使用列表

Question

我有一个数据框我想绘制为条形图，但我希望分类x值按照我用列表指定的特定顺序。我将使用mtcars数据集显示一个示例。

#get a small version of the mtcars dataset and add a named column 
mtcars2 <- mtcars 
mtcars2[["car"]] <- rownames(mtcars2) 
mtcars2 <- mtcars[0:5,] 
# I would like to plot this using the following 
p = ggplot(mtcars2, aes(x=car, y=mpg))+ geom_bar(stat="identity") 

x轴的值按字母顺序排序。但是，如果我有车的名单，我想ggplot到订单保留：

#list out of alphabetical order 
orderlist = c("Hornet 4 Drive", "Mazda RX4 Wag", "Mazda RX4", 
       "Datsun 710", "Hornet Sportabout") 

# I would like to plot the bar graph as above but preserve the plot order 
# something like this: 
p = ggplot(mtcars2, aes(x= reorder(car, orderlist), y=mpg))+ geom_bar(stat="identity") 

任何指针将不胜感激， 扎克CP

Answer 1

坐落在car因素的水平，你的订单希望他们，例如：

mtcars2 <- transform(mtcars2, car = factor(car, levels = orderlist)) 

然后积工作没有任何进一步的干预：

ggplot(mtcars2, aes(x=car, y=mpg))+ geom_bar(stat="identity")