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
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.
it works! Thanks Astounding!
Available on demand!
Missed SAS Innovate Las Vegas? Watch all the action for free! View the keynotes, general sessions and 22 breakouts on demand.
Learn how use the CAT functions in SAS to join values from multiple variables into a single value.
Find more tutorials on the SAS Users YouTube channel.