如何在R中基于两列信息生成指定映射的新列？

方法一：使用dplyr的case_when函数 #

这种方法直接通过条件判断完成映射，逻辑清晰，适合规则明确的场景：

首先加载dplyr包（未安装的话先运行install.packages("dplyr")）：

library(dplyr)

# 原始数据
example <- data.frame(
  sub = c(101, 101, 101, 102, 102, 102),
  trialtype = c("ReframeNeg", "ImmerseNeu", "ImmerseNeg", "ImmerseNeu", "ImmerseNeg", "ReframeNeg"),
  condition = c("Self", "Self", "Self", "Other", "Other", "Other")
)

# 创建新列并完成映射
example_solution <- example %>%
  mutate(trial = case_when(
    condition == "Self" & trialtype == "ReframeNeg" ~ "selfrefneg",
    condition == "Self" & trialtype == "ImmerseNeg" ~ "selfimmneg",
    condition == "Self" & trialtype == "ImmerseNeu" ~ "selfimmneut",
    condition == "Other" & trialtype == "ReframeNeg" ~ "socrefneg",
    condition == "Other" & trialtype == "ImmerseNeg" ~ "socimmneg",
    condition == "Other" & trialtype == "ImmerseNeu" ~ "socimmneut"
  ))

方法二：使用自定义映射表匹配 #

如果后续需要修改映射规则，这种方法更灵活，只需调整映射表即可：

# 原始数据
example <- data.frame(
  sub = c(101, 101, 101, 102, 102, 102),
  trialtype = c("ReframeNeg", "ImmerseNeu", "ImmerseNeg", "ImmerseNeu", "ImmerseNeg", "ReframeNeg"),
  condition = c("Self", "Self", "Self", "Other", "Other", "Other")
)

# 定义映射规则
map_rules <- c(
  "SelfReframeNeg" = "selfrefneg",
  "SelfImmerseNeg" = "selfimmneg",
  "SelfImmerseNeu" = "selfimmneut",
  "OtherReframeNeg" = "socrefneg",
  "OtherImmerseNeg" = "socimmneg",
  "OtherImmerseNeu" = "socimmneut"
)

# 先合并列，再匹配映射规则
example_solution <- example %>%
  mutate(combined = paste0(condition, trialtype),
         trial = map_rules[combined]) %>%
  select(-combined)  # 移除临时合并的列

验证结果 #

运行上述代码后，执行print(example_solution)即可得到期望的输出：

sub    trialtype condition       trial
1 101   ReframeNeg      Self  selfrefneg
2 101   ImmerseNeu      Self selfimmneut
3 101   ImmerseNeg      Self  selfimmneg
4 102   ImmerseNeu     Other socimmneut
5 102   ImmerseNeg     Other  socimmneg
6 102   ReframeNeg     Other  socrefneg

内容的提问来源于stack exchange，提问作者jo_