如何在R中分組因子水平

Question

我有一個包含足球位置縮寫的因子列，其中包含大約17個具有220個觀測值的唯一值。我想只有三個因素水平，涵蓋了17個獨特的價值觀。

levels(nfldraft$Pos) <- list(Linemen = c("C","OG","OT","TE","DT","DE"), Small_Backs = c("CB","WR","FS"), Big_Backs = c("FB","ILB","OLB","P","QB","RB","SS","WR")) 

是我試過，打印nfldraft$Pos到控制檯顯示了3點因子的水平，但所有的值或者是架線工或Small_Backs和所有其他的人都是NA。我哪裏錯了？謝謝

Answer 1

我提出了一個例子字符向量與所有的縮寫：

my_example <- c("C","OG","OT","TE","DT","DE","CB","WR","FS", 
       "FB","ILB","OLB","P","QB","RB","SS","WR") 
class(my_example) 

[1]我取代所期望的水平及其縮寫「字符」

然後（您也可以在這裏使用gsub或許多不同方法中的任何一種）：

my_example[my_example %in% c("C","OG","OT","TE","DT","DE")] <- "Linemen" 
my_example[my_example %in% c("CB","WR","FS")]    <- "Small Backs" 
my_example[my_example %in% c("FB","ILB","OLB","P", 
          "QB","RB","SS","WR")]   <- "Big Backs" 

然後我使它成爲一個因素：

my_example <- as.factor(my_example) 
head(my_example) 

[1] Linemen Linemen Linemen Linemen Linemen Linemen 
Levels: Big Backs Linemen Small Backs 

tail(my_example) 

[1] Big Backs Big Backs Big Backs Big Backs Big Backs Small Backs 
Levels: Big Backs Linemen Small Backs 

class(my_example) 

[1] 「因子」