Question

数据框'vpsots'有一个变量'type'，有13个级别（如下所示），而在探索数据框时，它试图用suv重新整合SUV（只是为了看看我能不能）。我应该在下面的代码中对警告做些什么。我看到SUV改为NA了。我认为它与变量'type'是一个因素有关。是因为级别'suv'不存在。我正在努力改善阅读警告标志并希望得到建议。

> unique(vposts$type)
 [1] coupe       SUV         sedan       hatchback   wagon       van         <NA>       
 [8] convertible pickup      truck       mini-van    other       bus         offroad    
13 Levels: bus convertible coupe hatchback mini-van offroad other pickup sedan SUV ... wagon
> vposts$type[vposts$type=="SUV"]="suv"
Warning message:
In `[<-.factor`(`*tmp*`, vposts$type == "SUV", value = c(3L, NA,  :
  invalid factor level, NA generated
> unique(vposts$type)
 [1] coupe       <NA>        sedan       hatchback   wagon       van         convertible
 [8] pickup      truck       mini-van    other       bus         offroad    
13 Levels: bus convertible coupe hatchback mini-van offroad other pickup sedan SUV ... wagon

Answer 1

要重命名因子的级别，您可以使用levels函数执行以下操作：

# Create a factor with each alphabet letter as levels.
a_factor <- factor(substring("statistics", 1:10, 1:10), levels = letters)
summary(a_factor)

a b c d e f g h i j k l m n o p q r s t u v w x y z  
1 0 1 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 3 3 0 0 0 0 0 0

# Rename the level whose name is "c".
levels(a_factor)[levels(a_factor) == "c"] <- "CE"
summary(a_factor)

a  b CE  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x  y  z  
1  0  1  0  0  0  0  0  2  0  0  0  0  0  0  0  0  0  3  3  0  0  0  0  0  0

需要帮助解码警告

1 个答案: