st: Re: creating count within id and date

[Kit Baum <baum@bc.edu>]

. bys id date: g visitno = _n

     +------------------------------------+
     | id    date   var1   var2   visitno |
     |------------------------------------|
  1. |  1   16267      x     53         1 |
  2. |  1   16267      y    106         2 |
  3. |  1   16267      y     84         3 |
  4. |  1   16267      y     90         4 |
  5. |  1   16267      z     76         5 |
  6. |  1   16267      z     65         6 |
  7. |  1   16298      x     87         1 |
  8. |  1   16298      y     76         2 |
  9. |  2   15678      x     98         1 |
 10. |  2   15678      y     98         2 |
 11. |  2   16541      x    150         1 |
     +------------------------------------+

Kit Baum, Boston College Economics
http://ideas.repec.org/e/pba1.html

On Feb 27, 2005, at 2:33 AM, statalist-digest wrote:

> I have the following data structure
>
>     id       date        var1        var2
>
>     1        16267         x         53
>     1        16267         y        106
>     1        16267         y        84
>     1        16267         y        90
>     1        16267         z         76
>     1        16267         z         65
>     1        16298         x         87
>     1        16298         y        76
>     2        15678         x        98
>     2        15678         y        98
>     2         16541        x        150
>
> etc
> I wish to create identifier (visitno) 1,2,3,... for each sequential 
> date
> within id.
> I have tried to use :
> sort id date
> by id date: gen visitno = [_n]  which obviously doesnt produce the
> required variable
> I would be greatful for solution & ?or direction to FAQ dealing with
> this
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