How to find the week number of a month?

[AndyTeng]

Hi, everyone 

If I have a data format "20180825" for the Date column, how do I find the week number of the month for that date (i.e. the fourth week of Aug in 2018)? I need your help for this question ASAP. Thanks a lot.

[Jagadishkatam]

data have;
input date:anydtdte.;
 week=intck('week',intnx('month',date,0),date)+1; 
format date date9.;
cards;
20180825
;

[Astounding]

If you need the answer ASAP, you should provide the rest of the relevant information.

Is your date variable an eight-digit number, or is it an eight-digit character string, or is it already a SAS date?

What is your definition of a week?  Are the first seven days of the month all in week 1?  Even if the first of the month is Wednesday?

Depending on your answers, here is a formula that might come in handy:

weeknum = ceil(day(datevar) / 7);

[novinosrin]

@Astounding Sir, elegance personified. Very neat!

[AndyTeng]

Hi, Astounding 

Thank you for your reply. 

Yes, I think it's a eight-digit number. I don't have definite definition for the week number of a month. It would be fine if the program can help to show the sequence of a week within a month. BTW, I got the following message by implementing your suggested code: 

NOTE: Invalid argument to function DAY(20021030) at line 1998 column 33.

If you have any suggestion, please let me know. Thank you very much. 

[Jagadishkatam]

Hi I tried the below and it worked with no issues

data have;
input date:anydtdte.;
weeknum = ceil(day(date) / 7);
format date date9.;
cards;
20021030
;

[Astounding · Accepted solution]

That can be fixed.  You need to treat the date as a valid SAS date, not as an eight-digit number.  Unfortunately, it gets a little complex, so I'll break it out as two separate statements:

data want;

set have;

true_sasdate = input(put(datevar, z8.), yymmdd8.);

weeknum = ceil( day(true_sasdate) / 7);

run;

[AndyTeng]

Hi, Astounding
It works!
Yes, I have to transform the date to a valid SAS date first.
Thank you very much.