Replace a certain repeated value

[Tomas Jankelevich]

Hello,
I have a panel and I have an event (turnover). The thing is sometimes i have this event twice and i need only to consider the first event. So when turnover=1 twice for the same id, y want to replace the second turnover to zero. In the example below, you can see turnover happens twice on id=2, once in 1930 and once in 1933. I want to change the 1933 turnover dummy to zero. This for a long panel data, so replace turnover=0 if id==2 & year==1933 would take me days. Is there a simpler way?

id year turnover
 2 1926 .
 2 1927 .
 2 1928 0
 2 1929 0
 2 1930 1
 2 1931 0
 2 1932 0
 2 1933 1
 2 1934 0
 2 1935 .
 3 1926 .
 3 1927 .
 3 1928 0
 3 1929 0
 3 1930 0
 3 1931 0
 3 1932 0
 3 1933 0
 3 1934 0
 3 1935 .
 4 1926 .
 4 1927 .
 4 1928 0
 4 1929 0
 4 1930 1
 4 1931 0
 4 1932 0
 4 1933 0
 4 1934 0
 4 1935 .
 end

thanks

[William Lisowski]

This seems to do the job (I altered your sample data to make a more interesting example.)

clear
input float(id year turnover)
2 1926 .
2 1927 .
2 1928 0
2 1929 0
2 1930 1
2 1931 0
2 1932 0
2 1933 1
2 1934 0
2 1935 .
3 1926 .
3 1927 .
3 1928 0
3 1929 1
3 1930 0
3 1931 1
3 1932 0
3 1933 1
3 1934 0
3 1935 .
4 1926 .
4 1927 .
4 1928 0
4 1929 0
4 1930 1
4 1931 1
4 1932 1
4 1933 0
4 1934 0
4 1935 .
end
generate newturnover = turnover
bysort id (year): replace newturnover = 0 if turnover==1 & sum(turnover)>1
list, noobs sepby(id)

  +---------------------------------+
  | id   year   turnover   newtur~r |
  |---------------------------------|
  |  2   1926          .          . |
  |  2   1927          .          . |
  |  2   1928          0          0 |
  |  2   1929          0          0 |
  |  2   1930          1          1 |
  |  2   1931          0          0 |
  |  2   1932          0          0 |
  |  2   1933          1          0 |
  |  2   1934          0          0 |
  |  2   1935          .          . |
  |---------------------------------|
  |  3   1926          .          . |
  |  3   1927          .          . |
  |  3   1928          0          0 |
  |  3   1929          1          1 |
  |  3   1930          0          0 |
  |  3   1931          1          0 |
  |  3   1932          0          0 |
  |  3   1933          1          0 |
  |  3   1934          0          0 |
  |  3   1935          .          . |
  |---------------------------------|
  |  4   1926          .          . |
  |  4   1927          .          . |
  |  4   1928          0          0 |
  |  4   1929          0          0 |
  |  4   1930          1          1 |
  |  4   1931          1          0 |
  |  4   1932          1          0 |
  |  4   1933          0          0 |
  |  4   1934          0          0 |
  |  4   1935          .          . |
  +---------------------------------+

[Tomas Jankelevich]

Thanks! worked perfectly