Cartesian Product in SAS

Things under legendu.net/outdated are outdated technologies that the author does not plan to update any more. Please look for better alternatives.

Suppose we have 2 variables x = ("a", "b", "c") and y = (1, 2, 3), and we want to create a dataset containing the Cartesian product of x and y in SAS. This can be achieved by manually input the Cartesian product of x and y in a data step. However, this is infeasible when x and/or y is very large or x and/or y can only be determined at run time. Here I provide 2 two general ways to generate Cartesian product of x and y.

Use Outer Join of SQL

data x;
    input x$;
    datalines;
a
b
c
;
run;

data y;
    input y;
    datalines;
1
2
3
;
run;

proc sql;
    create table cart as
    select * from x, y
    ;
quit;

Use Loop in Data Step

If one of the 2 variables (whose Cartesian product is to be calculated) has an explicit expression (e.g., \(y_i = i\)), then we can also use a loop in a data step to calculate the Cartesian product.

data x;
    input x$;
    datalines;
a
b
c
;
run;

data cart;
    set x;
    do y=1 to 3;
        output;
    end;
run;

(Note: the loop trick a frequently used one in SAS to convert a "fat" data to a "thin" data.)