How to order my dataframe lexicographicaly

Question

I have a following data frame

a = data.frame(a=c(1,2,3,4,5,6,7),b=c(1,2,3,10,12,21,4),c=c(1,2,10,11,\"X\",\"Y\",3))
> a
  a  b  c
1 1  1  1
2 2  2  2
3 3         


        

Answer 1

Unfortunately mixedsort does not (yet) support multiple column sorting. So, you need to implement it yourself, for example like this:

a[order(sub("[0-9]+", "", a$c),
        as.numeric(sub("[[:alpha:]]*([[:digit:]]*)", '\\1', a$c)),
        as.numeric(a$b),
        as.numeric(a$a)), ]

This first, alphanumerically sorts data.frame using a$c, and for tie situations(which actually does not exist in your data.frame 'a'), it uses a$b and a$a.

Output is:

  a  b  c
1 1  1  1
2 2  2  2
7 7  4  3
3 3  3 10
4 4 10 11
5 5 12  X
6 6 21  Y

PS: This was written by David Winsemius in this post as a reply to a similar question.