R语言ifelse多分类变量转换错误问题求助

问题根源 #

你代码里的字符串匹配存在空格不一致的问题：示例数据中Chamber类的取值都是"Court (Xxx Section)"（Court和括号之间有空格），但你在ifelse里写的是"Court(Fifth Section)"（无空格），导致匹配失败，本该属于Chamber的类别全部落入了最后的else分支（Committee）。

解决方案 #

方案1：修正ifelse的匹配字符串

补全匹配字符串里的空格，修正后的代码如下：

df$origin.simple <- ifelse(df$Originating_body == "Court (Grand Chamber)" |
                           df$Originating_body == "Court (Plenary)", "Grand Chamber", 
                          ifelse(df$Originating_body == "Court (Chamber)" |
                                   df$Originating_body == "Court (Fifth Section)" |
                                   df$Originating_body == "Court (Fourth Section)" |
                                   df$Originating_body == "Court (Third Section)" |
                                   df$Originating_body == "Court (Second Section)" |
                                   df$Originating_body == "Court (First Section)", "Chamber", "Committee"))

方案2：用dplyr::case_when（更清晰易读）

嵌套ifelse层级过多易出错，case_when的语法更直观，也能降低拼写失误概率：

library(dplyr)

df <- df %>%
  mutate(origin.simple = case_when(
    Originating_body %in% c("Court (Grand Chamber)", "Court (Plenary)") ~ "Grand Chamber",
    Originating_body %in% c("Court (Chamber)", "Court (Fifth Section)", "Court (First Section)", 
                            "Court (Fourth Section)", "Court (Second Section)", "Court (Third Section)") ~ "Chamber",
    TRUE ~ "Committee" # 剩余类别自动归为Committee
  ))

方案3：直接重编码Factor（适用于原变量为Factor类型）

如果Originating_body是Factor类型，直接修改层级比转字符更高效：

# 确保变量为Factor类型
df$Originating_body <- factor(df$Originating_body)

# 重编码层级
levels(df$Originating_body) <- list(
  "Grand Chamber" = c("Court (Grand Chamber)", "Court (Plenary)"),
  "Chamber" = c("Court (Chamber)", "Court (Fifth Section)", "Court (First Section)", 
                "Court (Fourth Section)", "Court (Second Section)", "Court (Third Section)"),
  "Committee" = setdiff(levels(df$Originating_body), 
                        c("Court (Grand Chamber)", "Court (Plenary)", 
                          "Court (Chamber)", "Court (Fifth Section)", "Court (First Section)", 
                          "Court (Fourth Section)", "Court (Second Section)", "Court (Third Section)"))
)

# 可选：重命名变量
names(df)[names(df) == "Originating_body"] <- "origin.simple"

验证结果 #

执行完代码后，可通过table(df$origin.simple)查看分类计数，确认各类别是否正确归属。

内容的提问来源于stack exchange，提问作者Helga