mutate new column that matches to defined strings

Question

I would like to

mutate

one of the columns of data frame depending on the certain conditions matched. I have looked the around but couldn't find some neat solution so far on this. use-mutate-to-create-new-column-label-with-conditions

So here is the simple data frame that I used

gr = rep(seq(1,2),each=3)

clas=c("A_1","A_2","A_3","A_4","A_5","A_6")



df <- data.frame(gr,clas)



> df

  gr clas

1  1  A_1

2  1  A_2

3  1  A_3

4  2  A_4

5  2  A_5

6  2  A_6

I would like to chance A_4, A_5 and A_6 with B_1, B_2 and B_3

So I tried

match <- paste('_',seq(4,6),sep='')

 df%>%

  mutate(clas=ifelse(clas %in% match,paste('B',seq(1,3),sep='_'),clas))



       gr clas

    1  1    1

    2  1    2

    3  1    3

    4  2    4

    5  2    5

    6  2    6

and 2nd try with

grepl

df%>%

mutate(clas=ifelse(clas==grepl(paste(match,collapse='|'),clas),paste('B',seq(1,3),sep='_'),clas))



   gr clas

1  1    1

2  1    2

3  1    3

4  2    4

5  2    5

6  2    6

Which is A's also gone :) The expected result is;

   gr clas

1  1  A_1

2  1  A_2

3  1  A_3

4  2  B_1

5  2  B_2

6  2  B_3

Thanks!

EDIT: I realized that it is easier to do if there are LETTERS in the data

clas

column. But if we have data like this and no

gr

column how do we that ??

    clas

1   CD_1

2  X.2_2

3  K$2_3

4 12k3_4

5   .A_5

6   xy_6

The expected output is

    clas

1   CD_1

2  X.2_2

3  K$2_3

4 12kB_4

5   .B_5

6   xB_6

I guess I was looking for solution like that

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Answer 1

Here is dplyr solution:

df%>%group_by(gr)%>%dplyr::mutate(clas=paste0(toupper(letters[gr]),"_",row_number()))
#you can change toupper(letters[gr]) to LETTERS[gr]

# A tibble: 6 x 2
# Groups:   gr [2]
     gr  clas
  <int> <chr>
1     1   A_1
2     1   A_2
3     1   A_3
4     2   B_1
5     2   B_2
6     2   B_3

mutate new column that matches to defined strings

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