R 基于双重条件替换字符串

假设我有一个数据帧：

df <- data.frame(a=c("m,dt,f,m","dt,t,d,e","m,t,e,x", "m,x,dt,f"))

---

df使用lookaheads的完整示例：

library("stringr")
df <- data.frame(a=c("m,dt,f,m","dt,t,d,e","m,t,e,x", "m,x,dt,f"), stringsAsFactors = FALSE)
df$a[str_detect(df$a, "(?=.*\\bm\\b)(?=.*\\bdt\\b)")] = "John"
df

df$a[grepl（（？=.*dt）（？=.*m）”，df$a，perl=TRUE）]另一个更安全的选项
df$a[with（df，grepl（“dt”，a）和grepl（“m，a））]太棒了！不要以为你能解释，或者让我看一些解释边界部分的文本？当然：
library("stringr")
df <- data.frame(a=c("m,dt,f,m","dt,t,d,e","m,t,e,x", "m,x,dt,f"), stringsAsFactors = FALSE)
df$a[str_detect(df$a, "(?=.*\\bm\\b)(?=.*\\bdt\\b)")] = "John"
df

(?=.*\bm\b)   # looking for m with "boundaries
(?=.*\bdt\b)  # looking for dt with "boundaries"