R语言中na.omit函数

 

1、应用于向量

> a <- c("d", "e", NA, "k", NA, "m")
> a
[1] "d" "e" NA  "k" NA  "m"
> as.character(na.omit(a))               ## 清除向量中的空值
[1] "d" "e" "k" "m"
> na.omit(a)[1:length(na.omit(a))]       ## 清除向量中的空值
[1] "d" "e" "k" "m"

 

2、应用于数据框

> a <- c("d", "e", NA, "k", NA, "m")
> b <- 1:6
> c <- c(2, NA, 3, 7, 8, 9)
> d <- letters[1:6]
> e <- data.frame(a, b, c, d)
> e
     a b  c d
1    d 1  2 a
2    e 2 NA b
3 <NA> 3  3 c
4    k 4  7 d
5 <NA> 5  8 e
6    m 6  9 f
> na.omit(e)        ## 清除所有含有空值的行
  a b c d
1 d 1 2 a
4 k 4 7 d
6 m 6 9 f