topic Re: DIF / LAG function question. Please help in SAS Programming

DIF / LAG function question. Please help

RoWa — Wed, 01 Mar 2017 22:59:41 GMT

Hello,

What I have here is the date set looks like the following:

ID Month Year-to-date difference

01 201601 100 100

01 201602 105 5

01 201603 135 30

01 201604 205 70

01 201605 205 0

01 201606 205 0

01 201607 205 0

01 201608 205 0

01 201609 255 50

01 201610 255 0

01 201611 255 0

01 201612 255 0

02 201601 300 300

02 201602 405 105

02 201603 405 0

02 201604 435 30

01 201611 435 0

01 201612 455 20

as you can see it comes with different ID and different month, so I would like to get the difference from the year-to-date, but could not get any success.

my code is:

data want;

set have;

if Month='201601' then difference=(year-to-date-0);

else do;

difference = dif(year-to-date);

end;

run;

My result gave me negative number in 201602, and I could not understand it. Please help. Thx.

Re: DIF / LAG function question. Please help

art297 — Wed, 01 Mar 2017 23:15:09 GMT

I don't have any data to test it on, but does your variable name really contain dashes? They're invalid unless you have the option set to allow non-conforming variable names.

Other than that, I think diff works like lag and shouldn't be used conditionally. Possibly something like the following would produce what you want:

data want;
  set have;
    difference = dif(year-to-date);
    if Month='201601' then difference=(year_to_date);
run;

Art, CEO, AnalystFinder.com

Re: DIF / LAG function question. Please help

Ksharp — Thu, 02 Mar 2017 02:24:56 GMT

Arthur.T may want say this.

data want;
  set have;
by id;
    difference = dif(year-to-date);
    if first.id then difference=(year_to_date);
run;

Re: DIF / LAG function question. Please help

art297 — Thu, 02 Mar 2017 02:35:20 GMT

Xia,

In this case they appear to be one and the same. However, I agree, your suggestion would also be correct.

Art, CEO, AnalystFinder.com

p.s. You're back to working with SAS?

Re: DIF / LAG function question. Please help

Ksharp — Thu, 02 Mar 2017 03:00:47 GMT

Yes. Always.

Re: DIF / LAG function question. Please help

RoWa — Thu, 02 Mar 2017 05:06:25 GMT

hello Art, Thank you so very much, its very educational.

Re: DIF / LAG function question. Please help

RoWa — Thu, 02 Mar 2017 05:07:10 GMT

thank you, it worked perfectly, thank you again like always.