IF-THEN statement not performing math equations when condition is met.

[mariko5797]

I want unscheduled visits indicated by *.19 and *.2 to be marked as such in AVISITN and AVIST. For example, I want ID = 1, VISITNUM = 104 to result in AVISITN = 202.19, AVISIT = "3 Days Post Dose 2 (S)". However, both AVISITN and AVISIT are coming up as blank for those visits. 

data have;
 input ID VISIT $ VISITNUM @@;
 cards;
 1 DAY1 101
 1 DAY2 102
 1 DAY3 103
 1 DAY4 104.19
 1 DAY5 105
 2 DAY1 101
 2 DAY2 102.2
 2 DAY3 103
 3 DAY1 101
 3 DAY2 102
 3 DAY3 103.19
 3 DAY4 104
 3 DAY5 105
 ;
run;

data have2;
 set have;
 length avisit1 $30.;
 	visitnum1 = int(visitnum);
	if visitnum1 = 101					then do; avisit1n = 101; avisit1 = 'Dose 1'; 			end;
	if visitnum1 = 102					then do; avisit1n = 102; avisit1 = '3 Days Post Dose 1';end;
	if visitnum1 = 103					then do; avisit1n = 201; avisit1 = 'Dose 2';			end;
	if visitnum1 = 104					then do; avisit1n = 202; avisit1 = '3 Days Post Dose 2';end;
	if visitnum1 = 105					then do; avisit1n = 203; avisit1 = '7 Days Post Dose 2';end;

 	if visitnum ^= visitnum1			then do;
		if visitnum-visitnum1 = 0.19	then do; avisitn = avisit1n + 0.19; avisit = strip(avisit1)||' (S)'; end;
		if visitnum-visitnum1 = 0.20	then do; avisitn = avisit1n + 0.20; avisit = strip(avisit1)||' (T)'; end;
	end;
		else								 do; avisitn = avisit1n; avisit = avisit1; 						 end;
run;

Aside: I attempted to make WANT dataset, but it kept reading each spacing as a new variable.

data want;
 input ID AVISIT $ AVISITN @@;
 length AVIST $18.;
 cards;
 1 
 Dose 1            
 101
 1 
 3 Days Post Dose 1
 102
 1 
 Dose 2
 201
 1
 3 Days Post Dose 2 (S)
 201.19
 1 
 7 Days Post Dose 2
 203
 2 
 Dose 1 
 101
 2 
 3 Days Post Dose 1 (T)
 102.2
 2 
 Dose 2
 201
 3 Dose 1 101
 3 
 3 Days Post Dose 1 
 102
 3 
 Dose 2 (S)
 201.19
 3 
 3 Days Post Dose 2 
 202
 3 
 7 Days Post Dose 2 
 203
 ;
run;

[PaigeMiller · Accepted solution]

Computers cannot represent fractions (that are not integer powers of 2) exactly. So, if you want to find something that equals a fractional value, you may have to round.

Try

if round(visitnum-visitnum1,0.01) = round(0.19,0.01) then do;

or use the FUZZ function

if fuzz(visitnum-visitnum1-0.19)=0 then do;

[svh]

You could try the resolve() function to evaluate that expression in the section of the DATA step that seems to be causing the issue. Like this:

if resolve(visitnum-visitnum1) = 0.19	then do; avisitn = avisit1n + 0.19; avisit = strip(avisit1)||' (S)'; end;
if resolve(visitnum-visitnum1) = 0.20	then do; avisitn = avisit1n + 0.20; avisit = strip(avisit1)||' (T)'; end;