topic difference in one column within a group in SAS Programming

difference in one column within a group

michellel — Thu, 16 Apr 2015 20:23:24 GMT

Hi,

I have a question about how to calculate day difference from the first date within a group (ID). Thanks much for your answer.

My data looks like as below. There are two columns (ID, date) and some other columns, which I did not show here but I need keep. I need create a new variable date_diff to show day difference from the first date within each ID. I showed a example of ID=1 as below for how I need calculate.

ID date date_diff

1 06JUL2006 0

1 23JUL2006 23JUL2006 - 06JUL2006

1 08AUG2007 08AUG2007 - 06JUL2006

2 03DEC2004

2 01JAN2005

Re: difference in one column within a group

Astounding — Thu, 16 Apr 2015 20:33:27 GMT

Assuming your data are sorted properly, by ID DATE, here's an elegant way:

data want;

set have;

by id;

date_diff + dif(date);

if first.id then date_diff=0;

run;

(Of course, beauty is in the eye of the beholder.) Good luck.

Re: difference in one column within a group

michellel — Thu, 16 Apr 2015 20:54:34 GMT

it works! Thanks Astounding!