If-else then do in SAS

Question

Hi I would like to know the steps of a multiple if then condition.

I would like to do the following:

data _ ;
set _ ;
if condition 1 is true then do; 
if sub condition 1 is true then _ ;
else if sub condition2 is true then _;
else if ... ;
end;
else if condition 2 is true then do; /* Is it right? */
if sub condition 1 is true then _ ;
else if sub condition2 is true then _;
else if ... ;
end;
run;

Could you please tell me which the right steps are? I should include else if or else do?

For example: condition 1 can take values 1 or 0. sub-conditions (I will call them as test1,test2, test3, ...) are other conditions. So I would have something like :

data _ ;
set _ ;
if condition1 = 1 then do;
if test1 = . then test3=test2; else test3=test1; 
else if test1 = 'My test' or test2= 'My test' then test3=test2 else test3=test2; 
end; 
else if condition1=0 then do;
if test1 = . then test3=test2; else test3=test1; 
else if test1 = 'My test' or test2= 'My test' then test3=test2 else test3=test2; 
end; 
else test3=test2;
run;

A sample of data could be:

condition1   test1        test2
1             .            M
0             My test      .
1             Love        home
0             Home         .

what I would like to select is, based on condition1 values,

if condition1 is 1 and test1 is . then assign to test3 test2's value, otherwise test3=test1; and so on.

My expected output would be then:

condition1   test1        test2       test3
1             .            M           M
0             My test      .           My test
1             Love        home         Love
0             Home         .           Home

Not sure I understand what the question is. The DO/END block is just so you can replace a single statement with multiple statements. — Tom
In your example is the variable TEST1 numeric or character? In some places you are treating it as numeric, test1 = ., and in other places as character, test1 = 'My test'. You can use the missing() function to test if a variable is missing and it will work the same for numeric or character variables, plus it will detect special missing values like .A, .Z etc. — Tom
In a dataset I have found . and NA values (the latter as string). Is there any way to check the type of the variable? — user12907213

Tom Tom · Accepted Answer · 2020-09-02T17:43:59

Not sure what you are asking, but perhaps this will help you.

You can think of the nested ifs as additional conditions. So if you had

if test1 then do;
  if test2 then statement1 ;
  else if test3 then statement2 ;
end;

You could re-write it as

if test1 and test2 then statement1 ;
else if test1 and test3 then statement2 ;

If-else then do in SAS

1 Answers