Assigning Weeks

[jnivi]

Hi there, 

I have a fairly large dataset (data=have)with dates that spans from April 5, 2021 to December 31, 2022. 

I know the SAS date function usually assigns the week number based on the start of the year. However, I was wondering if there was another way to automatically assign a week number to each record in my dataset where 05Apr2021 to 11Apr2021 would be assigned week 1 (not week 0 ),  12Apr2021 to 17Apr2021 would be assigned week 2, and so forth. 

Obs       ID                  Date                     Week

1          1001          05APR2021                  1

2          1002         19 APR2021                  3

3          2040         01JAN2022                   

4         7680         08APR2021                   2

5         5432        30DEC2022

Thank you!!

[Kurt_Bremser]

proc sql noprint;
select min(date) into :begin
from have;
quit;

data want;
set have;
week = intck(`week`,&begin.,date,'c') + 1;
run;

[AMSAS]

Although the code @Kurt_Bremser has supplied works for the example data provided. You also need to be aware that it ONLY works assuming your input data earliest observation has date="05APR2021"d 

If you were to run this code against another dataset that which has a different value earliest value for date, e.g. 01APR2021 then week 1 is going to be 01APR2021- 07APR2021.

If you want have consistent behavior where week 1 is always 05APR2021-11APR2021 then you are going to want to remove the PROC SQL step and hard code your starting date (&begin) 

INTCK Function

data have ;
	format date date7. ;
	do i=3 to 100 by 3 ;
		date="04APR2021"d+i  ;
		output have ;
	end ;
run ;

proc sort data=have ;
	by date ;
run ;

data want;
	set have;
	week=intck("week","05APR2021"d,date,'c') + 1;
run;