R语言中实现数据框或矩阵中字符串的批量替换

 

1、数据框或矩阵中字符串的批量替换

> a <- c("a","d", "v", "c")
> b <- c("c", "b", "a", "d")
> c <- c("m", "a", "d", "b")
> d <- data.frame(a, b, c)
> d
  a b c
1 a c m
2 d b a
3 v a d
4 c d b
> d[d == "d"] = "xxx"       ## 将数据框中的“d”替换为“xxx”
> d
    a   b   c
1   a   c   m
2 xxx   b   a
3   v   a xxx
4   c xxx   b

 

2、对指定列中的字符串进行替换

> a <- c("a","d", "v", "c")
> b <- c("c", "b", "a", "d")
> c <- c("m", "a", "d", "b")
> d <- data.frame(a, b, c)
> d
  a b c
1 a c m
2 d b a
3 v a d
4 c d b
> d[,2][d[,2] == "d"] = "xxx"    ## 将第2列中的“d”替换为“xxx”
> d
  a   b c
1 a   c m
2 d   b a
3 v   a d
4 c xxx b

 

> a <- c("a","d", "v", "c")
> b <- c("c", "b", "a", "d")
> c <- c("m", "a", "d", "b")
> d <- data.frame(a, b, c)
> d
  a b c
1 a c m
2 d b a
3 v a d
4 c d b
> for (i in c(1,3)) {               ## 将1和3列中的“d”替换为“xxx”
+   d[,i][d[,i] == "d"] = "xxx"
+ }
> d
    a b   c
1   a c   m
2 xxx b   a
3   v a xxx
4   c d   b

 

> a <- c("a","d", "v", "c")
> b <- c("c", "b", "a", "d")
> c <- c("m", "a", "d", "b")
> d <- data.frame(a, b, c)
> d
  a b c
1 a c m
2 d b a
3 v a d
4 c 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   c
1   a c   m
2 xxx b   a
3   v a xxx
4   c 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 <- c("m", "a", "d", "b")
> d <- data.frame(a, b, c)
> d
  a b c
1 a c m
2 d b a
3 v a d
4 c d b
> d[3,][d[3,] == "d"] = "xxx"          ## 将第3行中的“d”替换为“xxx”
> d
  a b   c
1 a c   m
2 d b   a
3 v a xxx
4 c d   b

 

> a <- c("a","d", "v", "c")
> b <- c("c", "b", "a", "d")
> c <- c("m", "a", "d", "b")
> d <- data.frame(a, b, c)
> d
  a b c
1 a c m
2 d b a
3 v a d
4 c d b
> for (i in c(2,4)) {                     ## 利用for循环将2,4行中的“d”替换为“xxx”
+   d[i,][d[i,] == "d"] = "xxx"
+ }
> d
    a   b c
1   a   c m
2 xxx   b a
3   v   a d
4   c xxx b

 

> a <- c("a","d", "v", "c")
> b <- c("c", "b", "a", "d")
> c <- c("m", "a", "d", "b")
> d <- data.frame(a, b, c)
> d
  a b c
1 a c m
2 d b a
3 v a d
4 c d b
> d[c(2,4),][d[c(2,4),] == "d"] = "xxx"      ##  将2,4行中的“d”替换我“xxx”
> d
    a   b c
1   a   c m
2 xxx   b a
3   v   a d
4   c xxx b