本文介绍了将NA转换为因子水平的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我有一个具有NA
值的向量,我想用一个新的因子水平NA
代替.
I have a vector with NA
values that I would like to replace by a new factor level NA
.
a = as.factor(as.character(c(1, 1, 2, 2, 3, NA)))
a
[1] 1 1 2 2 3 <NA>
Levels: 1 2 3
这有效,但似乎是一种奇怪的方法.
This works, but it seems like a strange way to do it.
a = as.factor(ifelse(is.na(a), "NA", a))
class(a)
[1] "factor"
这是预期的输出:
a
[1] 1 1 2 2 3 NA
Levels: 1 2 3 NA
推荐答案
您可以使用addNA()
.
x <- c(1, 1, 2, 2, 3, NA)
addNA(x)
# [1] 1 1 2 2 3 <NA>
# Levels: 1 2 3 <NA>
这基本上是使用exclude = NULL
分解的便捷功能.来自help(factor)
-
This is basically a convenience function for factoring with exclude = NULL
. From help(factor)
-
所以这很好的另一个原因是,如果您已经具有因子f
,则可以使用addNA()
快速将NA
作为因子级别添加而无需更改f
.如文档中所述,这对于表很方便.它也很好看.
So another reason this is nice is because if you already have a factor f
, you can use addNA()
to quickly add NA
as a factor level without changing f
. As mentioned in the documentation, this is handy for tables. It also reads nicely.
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