Sorting by descending order and delete observations

[Ed Suh]

Hi,

I would like to sort the observations by descending orders and only keep the first observation.

For instance, the data looks like this:

State            County       Programtype         Begin Date
1                     2                  6                       2007/01/01
1                     2                  6                       2008/01/01
1                     2                  5                       2009/01/01

2                     3                   4                     2006/01/01
2                     3                   3                     2008/01/01
2                     3                   3                     2011/01/01

I would like to first sort the data and keep only 1 observation by state/county with the most recent begin start date.

Thank you very much for your help!

[William Lisowski]

Why not sort the observations in ascending order and only keep the last observation for each state/county?

. * Example generated by -dataex-. To install: ssc install dataex
. clear

. input byte(state county programtype) float begin

        state    county  progra~e      begin
  1. 1 2 6 17167
  2. 1 2 6 17532
  3. 1 2 5 17898
  4. 2 3 4 16802
  5. 2 3 3 17532
  6. 2 3 3 18628
  7. end

. format %td begin

. by state county (begin), sort: generate tokeep = _n==_N

. list, sepby(state county)

     +------------------------------------------------+
     | state   county   progra~e       begin   tokeep |
     |------------------------------------------------|
  1. |     1        2          6   01jan2007        0 |
  2. |     1        2          6   01jan2008        0 |
  3. |     1        2          5   01jan2009        1 |
     |------------------------------------------------|
  4. |     2        3          4   01jan2006        0 |
  5. |     2        3          3   01jan2008        0 |
  6. |     2        3          3   01jan2011        1 |
     +------------------------------------------------+

[Ed Suh]

Thank you very much!

I will try with the codes.