如何在 R 的同一列中将四个因子合并为两个？答案

【问题标题】：How to combine four factors into two in the same column in R?如何在 R 的同一列中将四个因子合并为两个？
【发布时间】：2014-02-04 18:04:14
【问题描述】：

我有一组数据，其中包括性别。但不是“女性”和“男性”，而是“女性”、“f”、“男性”和“m”4个类别。我正在尝试将所有“f”和“m”分别替换为“female”和“male”。

我在这里使用什么命令？

数据如下：

dt <- data.frame(...)

     Gender     Age    
1    female     24          
2         m     38      
3    female     29      
4         m     33      
5         m     49      
6         f     29      
7         f     26      
8         f     36      
9    female     58      
10        f     31      
11   female     31      
12        f     29      
13   female     19      
14     male     38      
15   female     63

我试过这段代码：

dt$Gender <- dt$Gender(c("female","female","male","male"))

但它说错误。

【问题讨论】：

欢迎来到 SO。您应该尝试提供minimally reproducible example，以便我们更轻松地为您提供帮助。

标签： r command statistics

【解决方案1】：

既然您在标题中提到了factor，那么您是否看过factor 函数？

x <- c("female", "f", "male", "m", "f", "undeclared")
y <- factor(x)
y
# [1] female     f          male       m          f          undeclared
# Levels: f female m male undeclared
levels(y) <- list("female" = c("female", "f"),
                  "male" = c("male", "m"),
                  "undeclared" = "undeclared")
y
# [1] female     female     male       male       female     undeclared
# Levels: female male undeclared

【讨论】：

【解决方案2】：

> #Use first 2 and last 4 cases in your data to demonstrate
> tt <- data.frame(Gender = as.factor(c("female", "m", "f", "female", "male", "female")), Age = as.numeric(c(24,38,29,19,38,63)))
> tt
  Gender Age
1 female  24
2      m  38
3      f  29
4 female  19
5   male  38
6 female  63

> str(tt)   # Check the structure of the data, make sure Gender is a factor
'data.frame':   6 obs. of  2 variables:
 $ Gender: Factor w/ 4 levels "f","female","m",..: 2 3 1 2 4 2
 $ Age   : num  24 38 29 19 38 63

> levels(tt$Gender)   # Show the levels of factor "Gender"
[1] "f"      "female" "m"      "male"  

> levels(tt$Gender) <- c("female","female","male","male")  
  # Assign new levels you want -- make sure they are in the same order as the old ones

> levels(tt$Gender)   # Now the identical levels are combined 
[1] "female" "male"

** 如果 Gender 不是一个因素，您可以使用as.factor() 更改变量类。

【讨论】：