topic Start an increment count based on changes in data values - how? in SAS Procedures

Start an increment count based on changes in data values - how?

justchecking — Wed, 21 Sep 2011 22:11:32 GMT

Okay - I realize this is probably extremely easy to do in SAS but I for the life cannot figure it out - everything I've tried has not worked the way I need it to and am at my wits end. Any help would be greatly appreciated.

Let's say I have the following dataset in my work direcotry that consist of the first name of a customer and their date of purchase:

First_Name	Date_of_Purchase
John	01/01/2010
Jill	01/01/2010
Beth	01/01/2010
Will	02/01/2010
Jen	02/01/2010
Lori	03/01/2010
Tom	03/01/2010
Heidi	04/01/2010

What I need to do is an incremental count based on the change in date_of_purchase starting with the value of 1, results of which is shown below. I've tried various do-loop statements but cannot seem to populate the variable count with the value when the date remains unchanged (for example, for 01/01/2010, I've no problem populating first.date_of_purchase with 1, but subsequent cells under Count tied to 01/01/2010 remain empty. I've about 3 years worth of purchase data, with over thousand of customers. Thanks! If any clarification is needed, don't hestitate to let me know.

First_Name	Date_of_Purchase	Count
John	01/01/2010	1
Jill	01/01/2010	1
Beth	01/01/2010	1
Will	02/01/2010	2
Jen	02/01/2010	2
Lori	03/01/2010	3
Tom	03/01/2010	3
Heidi	04/01/2010	4

Start an increment count based on changes in data values - how?

art297 — Wed, 21 Sep 2011 22:27:00 GMT

Are you trying to increment based on number of purchases (which aren't shown in your sample data) or simply by number of months since 1JAN2010?

Start an increment count based on changes in data values - how?

Howles — Thu, 22 Sep 2011 01:20:29 GMT

data want ;

set have ;

by Date_of_Purchase ;

Count + first.Date_of_Purchase ;

run ;

Start an increment count based on changes in data values - how?

Ksharp — Thu, 22 Sep 2011 05:27:46 GMT

If the order were the same with the order at your post.

That will be easy.

data want;

set have;

if date_of _purchase ne lag(date_of_purchase) then count+1;

run;

Ksharp