choosing observations based on first occurence of a varaiable

[AKHILA]

Hi all,

I have a dataset as:

Id.no  Number  Flag

101      543         0

101      657         0

101      723         1

101      123         0

101       432        0

102        564        0

102        634       1

102       327        0

103        765       0

103         567      0

103        908       0

103        432       1

103       231        0

Can I get the observations upto the first occurrence of flag variable as '1' for each id no? I mean the output dataset as:

Id.no  Number  Flag

101      543         0

101      657         0

101      723         1

102        564        0

102        634       1

103        765       0

103         567      0

103        908       0

103        432       1

Please help me out for this . Thank you

[Kurt_Bremser]

data want;
set have;
by id;
retain write;
if first.id then write = 1;
if write then output;
if flag then write = 0;
run;

This makes use of the fact that 0 and missing are considered false, and any other non-missing value true.

[Kurt_Bremser]

Please take note that a variable does not "occur". It's either present in a dataset (and therefore the data step that reads it) or not. Values occur.

[novinosrin · Accepted solution]

data have;
input Id_no  Number  Flag;
cards;
101      543         0

101      657         0

101      723         1

101      123         0

101       432        0

102        564        0

102        634       1

102       327        0

103        765       0

103         567      0

103        908       0

103        432       1

103       231        0
;

data want;
 do until(last.id_no);
  set have;
  by id_no;
  if _n_ then output;
  if flag then _n_=0;
 end;
run;
proc print noobs;run;

Id_no	Number	Flag
101	543	0
101	657	0
101	723	1
102	564	0
102	634	1
103	765	0
103	567	0
103	908	0
103	432	1

[AKHILA]

Thank you so much!!