BookmarkSubscribeRSS Feed
☑ This topic is solved. Need further help from the community? Please sign in and ask a new question.
sasphd
Lapis Lazuli | Level 10

Hello, 

How to obtain previous observation by id

Have

secid sas_date      TNA

1        201501           345

1        201502         234

2        201501          278

2       201502           876

 

want 

secid sas_date      TNA

1        201501           .

1        201502         345

2        201501          .

2       201502           278

1 ACCEPTED SOLUTION

Accepted Solutions
ballardw
Super User

It really is a good idea to be consistent about use of variable names. You said "by id" which makes me guess that you mean secid variable. Having to guess can result in poor performance.

 

One way: This adds a new variable Ltna so you can compare the results for accuracy.

data want;
   set have;
   by notsorted secid;
   ltna= lag(tna);
   if first.secid then call missing(ltna);
run;

The By statement assumes your data is at least grouped by Secid if not sorted by such. The By statement makes automatic variables that indicate whether the current record is either the first or last of a by group.

The Lag function returns values from the previous record with some limitations. The above approach always gets a previous value and then sets it to missing when it is the first of Secid group.

View solution in original post

1 REPLY 1
ballardw
Super User

It really is a good idea to be consistent about use of variable names. You said "by id" which makes me guess that you mean secid variable. Having to guess can result in poor performance.

 

One way: This adds a new variable Ltna so you can compare the results for accuracy.

data want;
   set have;
   by notsorted secid;
   ltna= lag(tna);
   if first.secid then call missing(ltna);
run;

The By statement assumes your data is at least grouped by Secid if not sorted by such. The By statement makes automatic variables that indicate whether the current record is either the first or last of a by group.

The Lag function returns values from the previous record with some limitations. The above approach always gets a previous value and then sets it to missing when it is the first of Secid group.

sas-innovate-2024.png

📢

ANNOUNCEMENT

The early bird rate has been extended! Register by March 18 for just $695 - $100 off the standard rate.

 

Check out the agenda and get ready for a jam-packed event featuring workshops, super demos, breakout sessions, roundtables, inspiring keynotes and incredible networking events. 

 

Register now!

What is Bayesian Analysis?

Learn the difference between classical and Bayesian statistical approaches and see a few PROC examples to perform Bayesian analysis in this video.

Find more tutorials on the SAS Users YouTube channel.

Click image to register for webinarClick image to register for webinar

Classroom Training Available!

Select SAS Training centers are offering in-person courses. View upcoming courses for:

View all other training opportunities.

Discussion stats
  • 1 reply
  • 274 views
  • 4 likes
  • 2 in conversation