R语言：为DataFrame新增Coinfection列标记合并感染状态

需求说明 #

在包含42列的DataFrame中新增一列Coinfection：

• 若某一行中Detected的出现次数≥2，标记为Coinfection
• 若仅1次或全为Not Detected，标记为Negative

示例数据构造 #

ID<- c(1,2,3,4,5)
CV<- c("Detected", "Not Detected", "Detected", "Not Detected", "Detected")
RV<- c("Not Detected", "Detected", "Not Detected", "Detected", "Not Detected")
BP<- c("Detected", "Detected", "Not Detected", "Detected", "Detected")
df <- data.frame(ID, CV, RV, BP)

解法1：Base R 实现 #

直接用rowSums统计每行Detected的数量，再通过ifelse完成标记：

# 排除ID列，统计其余列中"Detected"的出现次数
df$Coinfection <- ifelse(rowSums(df[-1] == "Detected") >= 2, "Coinfection", "Negative")

解法2：dplyr 实现（tidyverse风格） #

适合习惯tidyverse语法的用户，按行统计后完成标记：

library(dplyr)

df <- df %>%
  rowwise() %>%
  # 统计除ID外所有列中"Detected"的次数
  mutate(detected_num = sum(c_across(-ID) == "Detected")) %>%
  # 根据次数设置标记
  mutate(Coinfection = case_when(
    detected_num >= 2 ~ "Coinfection",
    TRUE ~ "Negative"
  )) %>%
  ungroup() %>%
  select(-detected_num) # 可选：移除中间计数列

验证结果 #

执行上述代码后，打印df即可得到期望的结果：

ID           CV           RV           BP Coinfection
1  1      Detected Not Detected      Detected Coinfection
2  2 Not Detected      Detected      Detected Coinfection
3  3      Detected Not Detected Not Detected    Negative
4  4 Not Detected      Detected      Detected Coinfection
5  5      Detected Not Detected      Detected Coinfection

内容的提问来源于stack exchange，提问作者T.McMillen