当某些列在 R 中具有某些值时删除某些列

Question

我需要删除其中具有特定值的某些列。

这是一个示例数据集:

df <- data.frame(var1 = c(1,2,3,4,5),
                 var2 = c("a","b","c","d","e"),
                 var3 = c("[Name A]","[Surname B]",NA, NA, NA),
                 var4 = c("[Name A]","[Surname B]",NA, NA, NA))


> df
  var1 var2        var3        var4
1    1    a    [Name A]    [Name A]
2    2    b [Surname B] [Surname B]
3    3    c        <NA>        <NA>
4    4    d        <NA>        <NA>
5    5    e        <NA>        <NA>

var3 和 var4 有 [Name A] 和 [Surname B] 然后是 NA 当列具有这种模式时，我需要将其删除。

我怎样才能获得下面所需的数据集:

> df1
  var1 var2       
1    1    a    
2    2    b 
3    3    c       
4    4    d      
5    5    e       

Answer 1

index <- sapply(
  df,
  FUN = function(x){
    ifelse(
      x[[1]] == "[Name A]" & x[[2]] == "[Surname B]",
# modify this ifelse to match exactly what you want, e.g. certain number of NA, remainder of values are NA, etc
      FALSE,
      TRUE
    )
  }
)



 index
# var1  var2  var3  var4 
#  TRUE  TRUE FALSE FALSE 
 


df[,index]
#  var1 var2
# 1    1    a
# 2    2    b
# 3    3    c
# 4    4    d
# 5    5    e