How can I Effectively Delete the Data Record (only one line) in Long Format Dataset with Stata Code?

[smith Jason]

Hello,
I have a long format dataset below. I really want to remove the data records having one line (grade=1/0 or grade=.)
How can I achieve my goal with Stata code?
Thank you!



clear
input str10 id byte (grade state)
1 1 0
1 2 0
1 3 0
1 4 0
1 5 0
1 6 0
1 7 0
1 8 0
1 9 0
1 10 0
1 11 0
1 12 0
2 1 0
2 2 0
2 . .
2 4 0
2 . .
2 6 0
2 7 0
2 8 0
2 . .
2 10 0
2 11 0
2 12 0
3 1 0
3 2 0
3 3 0
3 4 0
3 5 0
3 6 0
3 7 0
3 8 0
3 9 0
3 10 0
3 . .
3 11 0
4 1 0
4 . .
4 3 0
4 4 0
4 5 0
4 6 0
4 . .
4 . .
4 . .
4 . .
4 . .
4 12 0
5 1 0
5 2 0
5 . .
5 . .
5 . .
5 . .
5 . .
5 . .
5 . .
5 . .
5 . .
5 9 0
6 1 0
6 1 1
7 1 0
7 . .
7 . .
7 . .
7 . .
7 4 0
7 5 0
7 6 0
7 7 0
7 7 1
8 . 0
9 1 1
10 . 1
11 0 1
end

[Clyde Schechter]

What do you mean? There are no observations with grade = 1/0, and there can't be because "1/0" would only be possible with a string variable, which grade is not. Do you mean you want to eliminate all observations where grade is either 0, 1, or missing? If so

drop if inlist(grade, 0, 1, .)

If that's not what you mean, please post back with a clear explanation of what you want. Perhaps better still, point out exactly which observations in the example data you wish to delete.

[smith Jason]

Thank you. The data record with Id=8 id=9 id =10 id=11 is what I want to delete.

[William Lisowski]

My guess is that the objective is to delete any id that has just a single observation - id 8, 9, 10, and 11 at the end of the example data.

generate id_num = real(id)
sort id_num, stable
by id_num: generate todrop = _N==1
tab id todrop
drop if todrop==1
drop todrop id_num
tab id

. generate id_num = real(id)

. sort id_num, stable

. by id_num: generate todrop = _N==1

. tab id todrop

           |        todrop
        id |         0          1 |     Total
-----------+----------------------+----------
         1 |        12          0 |        12
        10 |         0          1 |         1
        11 |         0          1 |         1
         2 |        12          0 |        12
         3 |        12          0 |        12
         4 |        12          0 |        12
         5 |        12          0 |        12
         6 |         2          0 |         2
         7 |        10          0 |        10
         8 |         0          1 |         1
         9 |         0          1 |         1
-----------+----------------------+----------
     Total |        72          4 |        76

. drop if todrop==1
(4 observations deleted)

. drop todrop id_num

. tab id

         id |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         12       16.67       16.67
          2 |         12       16.67       33.33
          3 |         12       16.67       50.00
          4 |         12       16.67       66.67
          5 |         12       16.67       83.33
          6 |          2        2.78       86.11
          7 |         10       13.89      100.00
------------+-----------------------------------
      Total |         72      100.00

.

Added in edit: original posting crossed with post #3, so I guessed correctly! But I shouldn't have had to guess, as Clyde suggests.

[smith Jason]

Thank you all!