[Hans Rahr]

Thank you, Hemanshu, but wouldn’t that end in an error message of “variable already defined” almost immediately?

[Nick Cox]

I don't follow #16. Hemanshu Kumar's code should generate new variables var_1 var_2 ... var_5

[Hemanshu Kumar]

Yes, I'm not sure why you would expect that error in #16.

Here is a toy example:

clear
input byte(ID recno Var)
1 1 1
2 4 3
2 2 2
2 3 1
2 1 4
2 5 6
1 2 2
end

// Hans' code
tostring Var, gen(strVar)
sort ID recno
by ID: gen aggregatedVar=strVar if _n==1
by ID: replace aggregatedVar=strVar[_n]+" "+aggregatedVar[_n-1] if _n>1
by ID: replace aggregatedVar=aggregatedVar[_N]

// Hemanshu's code
sort ID recno
forval i = 1/5 {
    by ID: gen Var_`i' = Var[`i']
}

which produces:

. list, noobs sepby(ID) abbrev(13)

  +-----------------------------------------------------------------------------------+
  | ID   recno   Var   strVar   aggregatedVar   Var_1   Var_2   Var_3   Var_4   Var_5 |
  |-----------------------------------------------------------------------------------|
  |  1       1     1        1             2 1       1       2       .       .       . |
  |  1       2     2        2             2 1       1       2       .       .       . |
  |-----------------------------------------------------------------------------------|
  |  2       1     4        4       6 3 1 2 4       4       2       1       3       6 |
  |  2       2     2        2       6 3 1 2 4       4       2       1       3       6 |
  |  2       3     1        1       6 3 1 2 4       4       2       1       3       6 |
  |  2       4     3        3       6 3 1 2 4       4       2       1       3       6 |
  |  2       5     6        6       6 3 1 2 4       4       2       1       3       6 |
  +-----------------------------------------------------------------------------------+

both types of code work, they just produce different types of results, as you can see.