data a;
input name $8. level 1.;
cards;
Alfred 1
Alice 2
Barbara 2
Carol 3
Brut 4
Kelly .
Juan 1
;
run;
data exp;
set a;
if level =. then exp = 'Unknown';
else if level = 1 then exp = 'Low';
else if level= 2 or 3 then exp ='Medium';
else exp = 'high';
run;
The output dor dataset exp is as below:
name | level | exp |
Alfred | . | Unknown |
Alice | 2 | Medium |
Barbara | 2 | Medium |
Carol | 3 | Medium |
Brut | 4 | Medium |
Kelly | . | Unknown |
Juan | 1 | Low |
Not sure why for level 4 exp is 'Medium'?
else if level= 2 or 3 then exp ='Medium';
is translated as
if (level = 2) or (3)
Now, in SAS the boolean value of "false" is represented by the number zero; any other numerical value means "true". "3" is therefore always true, and makes the whole condition always true, meaning that the branch for "high" will never be entered.
Edit: Heh, Josh beat me to it.
You would need to use the 'in' operator or list out each condition of the 'or' operator for the 'Medium' assignment.
else if level in(2 3) then exp ='Medium';
/* or */
else if level = 2 or level = 3 then exp = 'Medium';
I would also recommend you take a look at PROC FORMAT. It is useful for assignment logic like this.
Thanks for the solution, but I am intrested in understanding why exp for level 4 is 'Medium' when datastep written in that way.
Not 100% sure, but my hunch is that the expression is being evaluated like so..
if (level = 2) or ( 3 )
For your observation in question, level = 2 is evaulated as false, but (3) on it's own is always true. It would be like saying if 3 ^= .
The if statement returns a value of true, thus the assignment of 'Medium' takes place.
else if level= 2 or 3 then exp ='Medium';
is translated as
if (level = 2) or (3)
Now, in SAS the boolean value of "false" is represented by the number zero; any other numerical value means "true". "3" is therefore always true, and makes the whole condition always true, meaning that the branch for "high" will never be entered.
Edit: Heh, Josh beat me to it.
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