Replace first letter of a string

Question

I have a dataframe with a column I would like to change the string in it

       Num       rand
1  A.AZ.R   0.2500000
2  A.EAZ.B  1.0000000
3  A.AZ.C   0.1000000
4  A.AZE.D  0.0100000
5  A.AZE.E  0.2500000
6  A.RJE.F  0.0156250
7  A.AZE.C  0.0078125
8  A.AVE.G  0.0078125
9  A.AZD.B  0.0312500

I would like all A. be replaced by F. in the Num column.

       Num       rand
1  F.AZ.R   0.2500000
2  F.EAZ.B  1.0000000
3  F.AZ.C   0.1000000
4  F.AZE.D  0.0100000
5  F.AZE.E  0.2500000
6  F.RJE.F  0.0156250
7  F.AZE.C  0.0078125
8  F.AVE.G  0.0078125
9  F.AZD.B  0.0312500

gsub("R.", "F.", Df) :) – Henry dubois Jul 04 '18 at 09:15 — Henry dubois, Jul 04 '18 at 09:15

score 1 · Accepted Answer · answered Jul 04 '18 at 09:30

> df
      Num      rand
1  A.AZ.R 0.2500000
2 A.EAZ.B 1.0000000
3  A.AZ.C 0.1000000
4 A.AZE.D 0.0100000
5 A.AZE.E 0.2500000
6 A.RJE.F 0.0156250
7 A.AZE.C 0.0078125
8 A.AVE.G 0.0078125
9 A.AZD.B 0.0312500

> df[,1] <- gsub("^.", "F", df[,1])
> df
      Num      rand
1  F.AZ.R 0.2500000
2 F.EAZ.B 1.0000000
3  F.AZ.C 0.1000000
4 F.AZE.D 0.0100000
5 F.AZE.E 0.2500000
6 F.RJE.F 0.0156250
7 F.AZE.C 0.0078125
8 F.AVE.G 0.0078125
9 F.AZD.B 0.0312500

score 1 · Answer 2 · answered Jul 04 '18 at 09:37

1

Chartr is useful for that: Assuming your data frame is called df you can do:

df$Num <- chartr("A.", "F.", df$Num)

answered Jul 04 '18 at 09:37

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Replace first letter of a string

2 Answers2