Complex id variable column

Question

I am relatively new to R and trying to create a new variable as part of a homework assignment, any help would be appreciated!

I have a data set that looks like this:

State    agegr
1         15-17
1         18-20
1         21-24
2         15-17
2         18-20
2         21-24

Currently I have state as the ID column, however would like to modify it so that I have a single ID column showing the state and age range, something like this:

State
1-15
1-18
1-21
2-15
2-18
2-21

and be able to identify the state.

Read about http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example and clarify your problem — demonplus, May 12 '15 at 12:19
post actual code from R, not just your impression of the layout. — Pierre L, May 12 '15 at 12:22
Just use `paste`. You can also use some `gsub` if you really don't want the part after the "-" for "agegr". — A5C1D2H2I1M1N2O1R2T1, May 12 '15 at 12:23
I don't know the code... that is why I am asking. I have a very basic understanding of how R works.... — Marc Anthony Makens, May 12 '15 at 12:23
Use something like `paste(State, agegr)`. You can define a separator, for ex. `paste(State, agegr, sep="-")` — Ruthger Righart, May 12 '15 at 12:25

score 1 · Answer 1 · answered May 12 '15 at 12:52

Using your data:

df <- data.frame(State=c(1,1,1,2,2,2), agegr=c('15-17','18-20','21-24','15-17','18-20','21-24'), stringsAsFactors=F );
df;
##   State agegr
## 1     1 15-17
## 2     1 18-20
## 3     1 21-24
## 4     2 15-17
## 5     2 18-20
## 6     2 21-24

Here's an approach using sub() and paste():

data.frame(State=paste(df$State,sub('^(\\d+).*','\\1',df$agegr),sep='-'));
##   State
## 1  1-15
## 2  1-18
## 3  1-21
## 4  2-15
## 5  2-18
## 6  2-21

Here's an approach using strsplit() and paste():

data.frame(State=paste(df$State,unlist(strsplit(df$agegr,'-'))[c(T,F)],sep='-'));
##   State
## 1  1-15
## 2  1-18
## 3  1-21
## 4  2-15
## 5  2-18
## 6  2-21

Complex id variable column

1 Answers1