将 DataFrame 列转换为因子答案

【问题标题】：Convert DataFrame Column to Factors将 DataFrame 列转换为因子
【发布时间】：2020-04-15 18:04:57
【问题描述】：

R，RStudio

如何将 DataFrame 列转换为因子？

我希望 0 是“北”，1 是“南”，2 是“东”，3 是“西”。

directions <- data.frame(
                          state=c("New York","New Jersey","Deleware","Texax","Alaska"),
                          travel=c(0,0,3,2,1)
                        )

head(directions)

输出

       state travel
1   New York      0
2 New Jersey      0
3   Deleware      3
4      Texax      2
5     Alaska      1

我尝试了以下，但整个travel 列是NA

directions$travel <- factor(directions$travel,levels=c("North","South","East","West"))
head(directions)

输出

state travel
1   New York   <NA>
2 New Jersey   <NA>
3   Deleware   <NA>
4      Texax   <NA>
5     Alaska   <NA>

【问题讨论】：

标签： r dataframe na

【解决方案1】：

我们需要在labels中指定

factor(directions$travel,labels=c("North","South","East","West"))
#[1] North North West  East  South
#Levels: North South East West

如果我们需要自定义分组，请同时指定levels

factor(directions$travel,levels = c(0, 1, 2, 3), 
         labels=c("North","South","East","West"))

【讨论】：