Alexander - 2 years ago 100

R Question

I would like to

`mutate`

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`

`gr`

`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 Source

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
```

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