Diference Date (MONTH) by ID

[Andres_Fuentes1]

Hello good morning, I could not find the way to do the following, I have an ID and a date of a certain event. I must add the difference in months of an event with the following one by ID.

Example in excel in the photograph.

someone who can help me, Greetings.

[PaigeMiller]

And so what is the desired result? Do you want 9 for ID = 1 and 12 for ID = 2 and 12 for ID=3?

Is your date variable a character variable in SAS or a numeric variable in SAS? What does PROC CONTENTS say?

FYI, please do not provide data as screen captures from Excel. The preferred method to provide data is: 

https://blogs.sas.com/content/sastraining/2016/03/11/jedi-sas-tricks-data-to-data-step-macro/

[Reeza]

That's Excel, not SAS data shown. In the future please show the SAS version. I'm assuming you have your data imported and that your date are SAS dates, eg numeric with a date format.

proc sort data=have;
by ID;
run;

data want;
set have;

by ID;

prev_date = lag(date);

if not first.id then n_month = intck('month', date, prev_date, 'C');

run;

You may need to play with the INTCK() function to get the exact numbers you want but this gives you an idea of how to do it. 

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@Andres_Fuentes1 wrote:

Hello good morning, I could not find the way to do the following, I have an ID and a date of a certain event. I must add the difference in months of an event with the following one by ID.

Example in excel in the photograph.

someone who can help me, Greetings.

---

[Jerrya00 · Accepted solution]

Please try this:
proc sort data=your_data; by ID date;
run;

data results;
set your_data;
by ID date;;
retain pre_Date .;
if first.ID then do;
n_month=.;
pre_Date=date;
end;
else do;
n_month=intck('month', pre_Date, date, 'C');
pre_Date=date;
end;
drop pre_Date;
run;

[Andres_Fuentes1]

Nice, Thanks you.