add a new column based on other columns in sas - sas

Question

I'm new to SAS and would like to get help with the question as follows:
1: Sample table shows as below
Time Color Food label
2020 red Apple A
2019 red Orange A,B
2018 blue Apple A,B
2017 blue Orange B
Logic to return label is:
when color = 'red' then 'A'
when color = 'blue' then 'B'
when food = 'orange' then 'B'
when food = 'apple' then 'A',
since for row 2, we have both red and orange then our label should contains both 'A,B', same as row 3.
The requirement is to print out the label for each combination. I know that we can use CASE WHEN statement to define how is our label should be based on color and food. Here we only have 2 kind of color and 2 different food, but what if we like 7 different color and 10 different food, then we would have 7*10 different combinations. I don't want to list all of those combinations by using case when statement.
Is there any convenient way to return the label? Thanks for any ideas!(prefer to achieve it in PROC SQL, but SAS is also welcome)

Answer 1

This looks like a simple application of formats. So define a format that converts COLOR to a code letter and a second one that converts FOOD to a code letter.
proc format ;
value color 'red'='A' 'blue'='B';
value food 'Apple'='A' 'Orange'='B' ;
run;
Then use those to convert the actual values of COLOR and FOOD variables into the labels. Either in a data step:
data want;
set have ;
length label $5 ;
label=catx(',',put(color,color.),put(food,food.));
run;
Or an SQL query:
proc sql ;
create table want as
select *
, catx(',',put(color,color.),put(food,food.)) as label length=5
from have
;
run;
You do not need to re-create the format if the data changes, only if the list of possible values changes.