ggplot - 訂貨x軸標籤，通過多列

Question

與表像下面

df <- read.table(textConnection(" 
tier make model sales 
entry Toyota Yeti 10000 
entry Honda Jazz 8000 
entry Nissan Sunny 5000 
entry Honda Amaze 4000 
entry Toyota Model10 3500 
entry Nissan Beat 2000 
Mid Honda Civic 4000 
Mid Toyota Corolla 3000 
Mid Honda Accord 2500 
Mid Nissan Xtrail 2200 
Mid Toyota Camry 1800 
Mid Nissan Moon 800 
"), header = TRUE) 

> df 
    tier make model sales 
1 entry Toyota Yeti 10000 
2 entry Honda Jazz 8000 
3 entry Nissan Sunny 5000 
4 entry Honda Amaze 4000 
5 entry Toyota Model10 3500 
6 entry Nissan Beat 2000 
7 Mid Honda Civic 4000 
8 Mid Toyota Corolla 3000 
9 Mid Honda Accord 2500 
10 Mid Nissan Xtrail 2200 
11 Mid Toyota Camry 1800 
12 Mid Nissan Moon 800 

當我繪製使用ggplot通過模型的銷售爲以下我得到的情節在畫面

ggplot(df, aes(x=model, y=sales)) + 
    geom_point() 

正如所預期的，x軸標籤model在升序按照它們的電平 - Accord至上和Yeti最後。

> str(df) 
'data.frame': 12 obs. of 4 variables: 
$ tier : Factor w/ 2 levels "entry","Mid": 1 1 1 1 1 1 2 2 2 2 ... 
$ make : Factor w/ 3 levels "Honda","Nissan",..: 3 1 2 1 3 2 1 3 1 2 ... 
$ model: Factor w/ 12 levels "Accord","Amaze",..: 12 7 10 2 8 3 5 6 1 11 ... 
$ sales: int 10000 8000 5000 4000 3500 2000 4000 3000 2500 2200 ... 
> 

不過，我需要順序不同的model情節 - 當表由一線訂購了獲得，製造和銷售（下降）。我可以在下面的代碼中獲得該表的訂購順序 - 如何在圖中獲得model的x軸標籤的相同順序？

> df[with(df, order(tier, make, -sales)),] 
    tier make model sales 
2 entry Honda Jazz 8000 
4 entry Honda Amaze 4000 
3 entry Nissan Sunny 5000 
6 entry Nissan Beat 2000 
1 entry Toyota Yeti 10000 
5 entry Toyota Model10 3500 
7 Mid Honda Civic 4000 
9 Mid Honda Accord 2500 
10 Mid Nissan Xtrail 2200 
12 Mid Nissan Moon 800 
8 Mid Toyota Corolla 3000 
11 Mid Toyota Camry 1800 
> 

Answer 1

您可以更改模型變量的因子水平的順序，然後繪圖。就像這樣：

df <- df[with(df, order(tier, make, -sales)),] 
df$model <- factor(df$model, levels = unique(df$model)) 
ggplot(df, aes(x=model, y=sales)) + 
    geom_point() 

第一行改變行的順序。第二行是實際的重新排序。 unique(df$model)是變量的當前順序，並將其用作可按此順序繪製數據的因子級別。