Automating IF and then statement in sas using macro in SAS - if-statement

Question

I have a data where I have various types of loan descriptions, there are at least 100 of them.
I have to categorise them into various buckets using if and then function. Please have a look at the data for reference
data des;
set desc;
if loan_desc in ('home_loan','auto_loan')then product_summary ='Loan';
if loan_desc in ('Multi') then product_summary='Multi options';
run;
For illustration I have shown it just for two loan description, but i have around 1000 of different loan_descr that I need to categorise into different buckets.
How can I categorise these loan descriptions in different buckets without writing the product summary and the loan_desc again and again in the code which is making it very lengthy and time consuming
Please help!

Answer 1

Another option for categorizing is using a format. This example uses a manual statement, but you can also create a format from a dataset if you have the to/from values in a dataset. As indicated by #Tom this allows you to change only the table and the code stays the same for future changes.
One note regarding your current code, you're using If/Then rather than If/ElseIf. You should use If/ElseIf because then it terminates as soon as one condition is met, rather than running through all options.
proc format;
value $ loan_fmt
'home_loan', 'auto_loan' = 'Loan'
'Multi' = 'Multi options';
run;
data want;
set have;
loan_desc = put(loan, $loan_fmt.);
run;

Answer 2

For a mapping exercise like this, the best technique is to use a mapping table. This is so the mappings can be changed without changing code, among other reasons.
A simple example is shown below:
/* create test data */
data desc (drop=x);
do x=1 to 3;
loan_desc='home_loan'; output;
loan_desc='auto_loan'; output;
loan_desc='Multi'; output;
loan_desc=''; output;
end;
data map;
loan_desc='home_loan'; product_summary ='Loan '; output;
loan_desc='auto_loan'; product_summary ='Loan'; output;
loan_desc='Multi'; product_summary='Multi options'; output;
run;
/* perform join */
proc sql;
create table des as
select a.*
,coalescec(b.product_summary,'UNMAPPED') as product_summary
from desc a
left join map b
on a.loan_desc=b.loan_desc;
There is no need to use the macro language for this task (I have updated the question tag accordingly).

Answer 3

Already good solutions have been proposed (I like #Reeza's proc format solution), but here's another route which also minimizes coding.
Generate sample data
data have;
loan_desc="home_loan"; output;
loan_desc="auto_loan"; output;
loan_desc="Multi"; output;
loan_desc=""; output;
run;
Using PROC SQL's case expression
This way doesn't allow, to my knowledge, having several criteria on a single when line, but it really simplifies coding since the resulting variable's name needs to be written down only once.
proc sql;
create table want as
select
loan_desc,
case loan_desc
when "home_loan" then "Loan"
when "auto_loan" then "Loan"
when "Multi" then "Multi options"
else "Unknown"
end as product_summary
from have;
quit;
Otherwise, using the following syntax is also possible, giving the same results:
proc sql;
create table want as
select
loan_desc,
case
when loan_desc in ("home_loan", "auto_loan") then "Loan"
when loan_desc = "Multi" then "Multi options"
else "Unknown"
end as product_summary
from have;
quit;