使用case_when配合mutate生成新变量时为何报错？

我尝试用mutate修改一组变量，生成值已转换的新变量，代码如下：

ELSE <- TRUE

Engagement_Master <- Engagement_Master %>%
  mutate(`My work gives me a sense of personal accomplishment%` = case_when( 
    `My work gives me a sense of personal accomplishment` == "Strongly agree" ~ "1",
    `My work gives me a sense of personal accomplishment` == "Agree" ~ "1",
    `My work gives me a sense of personal accomplishment` == "Neither agree nor disagree" ~ "0",
    `My work gives me a sense of personal accomplishment` == "Disgree" ~ "0",
    `My work gives me a sense of personal accomplishment` == "Strongly disagree" ~ "0",
    ELSE ~ NA))

我一直收到如下错误：

Error in `mutate()`:
! Problem while computing `My work gives me a sense of personal accomplishment% = case_when(...)`.
Caused by error in `case_when()`:

我原本认为这段代码可以正常运行，因为之前用过相同的表达式且未出现错误。

问题分析与修复 #

1. 拼写错误：条件中的Disgree是拼写错误，正确应为Disagree，错误拼写会导致该选项无法被匹配，触发case_when分支不完整的错误。
2. 默认分支写法错误：case_when不需要提前定义ELSE <- TRUE，自定义的ELSE变量无法被识别为默认匹配条件，直接用TRUE ~ 结果作为默认分支即可。
3. 类型不一致：返回的"1""0"是字符型，而默认的NA是逻辑型，类型不匹配会引发问题，需用NA_character_保持字符型一致。

修正后的代码 #

Engagement_Master <- Engagement_Master %>%
  mutate(`My work gives me a sense of personal accomplishment%` = case_when(
    `My work gives me a sense of personal accomplishment` == "Strongly agree" ~ "1",
    `My work gives me a sense of personal accomplishment` == "Agree" ~ "1",
    `My work gives me a sense of personal accomplishment` == "Neither agree nor disagree" ~ "0",
    `My work gives me a sense of personal accomplishment` == "Disagree" ~ "0",
    `My work gives me a sense of personal accomplishment` == "Strongly disagree" ~ "0",
    TRUE ~ NA_character_
  ))

简化写法（可选） #

用%in%合并相同结果的条件，让代码更简洁：

Engagement_Master <- Engagement_Master %>%
  mutate(`My work gives me a sense of personal accomplishment%` = case_when(
    `My work gives me a sense of personal accomplishment` %in% c("Strongly agree", "Agree") ~ "1",
    .default = "0"
  ))
# 若需将未匹配值设为NA，替换.default为NA_character_

内容的提问来源于stack exchange，提问作者Karan Samtani