a b c1a c m2d b a3v a d4c d b> d[,c(1,3)][d[,c(1,3)] =="d"] ="xxx"## 将1、3列中的“d”替换为“xxx”>d a b c1a c m2xxx b a3v a xxx4c d b 3、对指定行中的字符串进行替换 > a <- c("a","d","v","c")> b <- c("c","b","a","d")> c <-...