topic selecting the series of observation based on some condition in SAS Programming

selecting the series of observation based on some condition

SASFREAK — Thu, 26 May 2016 13:20:04 GMT

Hi guys,

i have a data problem where i have to select out group of observation until certian condition is met ( until i have find flag=1). here is the sample datset:

data have;
input id flag;
cards;
001 0
001 0
001 0
001 1
001 0
001 0
002 0
002 1
002 0
;
run;

data want;
input id flag;
cards;
001 0
001 0
001 0
001 1
002 0
002 1
;
run;

i was trying to use do loop , but seems like i am doing something wrong:

here is my try:

data want;
do until(last.id);
   set have;
   by id;
   do _n_=1 to (f<=1);
       if f<=1;
   end;
   output;
   end;
stop;
run;

but it's not working. Any help is highly appreciated

Re: selecting the series of observation based on some condition

RW9 — Thu, 26 May 2016 14:00:46 GMT

Hi,

Something like:

data want (drop=op);
  set have;
  by id;
  retain op;
  if first.id then op=1;
  if op=1 then output;
  if flag=1 then op=0;
run;

Re: selecting the series of observation based on some condition

BrunoMueller — Thu, 26 May 2016 14:28:40 GMT

LAST.ID will be set to 1 as soon as the end of the first group is reached, so this is why, you only see one group.

Find below a code sample, that will do what you need. It is based on the SUM statement.

data want2;
  set have;
  by id;

  if first.id = 1 then do;
    flagCount = 0;
  end;
  flagCount + (flagCount + flag);

  if flagCount <= 1;
run;

Bruno

Re: selecting the series of observation based on some condition

FreelanceReinh — Thu, 26 May 2016 14:48:16 GMT

@SASFREAK: A DOW loop approach (do until(last. ...); set ...) was suggested for a very similar question in this recent thread.

Re: selecting the series of observation based on some condition

SASFREAK — Thu, 02 Jun 2016 13:06:35 GMT

@BrunoMueller Hi Bruno, Thanks for the solution, but what if i need like this

data have;
   infile cards missover;
    input id flag switch $8.;
cards;
001 0
001 0
001 0
001 1 first
001 0
001 0
001 1 second
001 0
001 0
002 0
002 1 first
002 0
002 0
002 1 second
002 1 third
;
run;

/*I need three outputs based on switches i,e.*/
/**/
/*data first will looks like:*/

data first;
    input id flag switch $8.;
cards;
001 0
001 0
001 0
001 1 first
002 0
002 1 first
;
run;

/*this is selecting observation from first to second*/
data second;
    input id flag switch $8.;
cards;
001 1 first
001 0
001 0
001 1 second
002 1 first
002 0
002 0
002 1 second
;
run;

data third;
    input id flag switch $8.;
cards;
002 1 second
002 1 third
;
run;

please help!

Re: selecting the series of observation based on some condition

BrunoMueller — Fri, 03 Jun 2016 16:29:56 GMT

You need to change the logic for this line

flagCount + (flagCount + flag);

so that you get the right setting.

For instance

flagCount + (flagCount + (switch = "first"));

will only write the observation til you reach switch = "first"

Bruno