topic Re: Do LOOP based on the value of a variable? in SAS Programming

Do LOOP based on the value of a variable?

UniversitySas — Sun, 03 May 2020 09:26:10 GMT

data temp;
infile DATALINES dsd missover;
input ID DATE(month_num) num_obs var1;
CARDS;
01, 1, 5, .
01, 2, 5, 1
01, 3, 5, 1
01, 4, 5, 2
01, 5, 5, 2
02, 1, 4, .
02, 2, 4, 1
02, 3, 4, 2
02, 4, 4, 3
02, 5, 4, 4
;
run;

I'm trying to do a do-loop that varies in the last iteration, for each id, based on the value of 'num_obs' for that ID.

So I want something like

DO i = 1 to num_obs;

END;

So that my DO loop evaluates from i = 1 to 5 for ID = 1,

then from i = 1 to 4 for ID = 2.

Is this possible?

I also need to use this in a macro, because for each loop, I'll be using i has a macro variable like so:

%DO i = 1 %to num_obs;

IF lag&i(var) = bla bla bla;

%END;

Is this possible?

Thanks

Re: Do LOOP based on the value of a variable?

PeterClemmensen — Sun, 03 May 2020 09:29:24 GMT

What is your desired result here?

Re: Do LOOP based on the value of a variable?

ed_sas_member — Sun, 03 May 2020 10:03:12 GMT

Hi @UniversitySas

You can definitely do a do-loop that varies in the last iteration, for each id, according to a variable.

Please have a look at the following result -> I have not dropped i so that you can see the number of iterations ->ex, for ID=01, numobs = 5, i looped from 1 to 5. When i=6, the do loop stops as 6 > numobs.

data want;
	set temp;
	do i = 1 to num_obs;
	end;
run;

proc print;

Regarding your second question, you cannot write this %DO i = 1 %TO numobs;

-> numobs should be a macrovariable.

Could you please give some more details about what you're going to achieve?

NB: another thing is that using the LAG function in an IF statement is not recommended at all, leading to unexpected results. You should fix the lagged values in a variables before using them in a conditional statement.

Best,