This Excel Lambda gist provides a lambda for building random combinations of dimension members

excel-lambda-RANDOMDB.txt

/*
Creates an empty array of r rows and c columns

Author: Owen Price
Date: 2022-09-14
*/
EMPTYARRAY = LAMBDA(r, [c], EXPAND({""}, r, IF(ISOMITTED(c), 1, c), ""));

/*
CROSSJOIN creates the cross-product of two arrays

Slightly modified from similar work by Erik Oehm

Author: Owen Price
Date: 2022-09-14
*/
CROSSJOIN = LAMBDA(array1, array2, [output],
    LET(
        _out, IF(ISOMITTED(output), EMPTYARRAY(1, COLUMNS(array1) + COLUMNS(array2)), output),
        _row, TAKE(array1, 1),
        _fn, LAMBDA(row, array, HSTACK(CHOOSEROWS(row, SEQUENCE(ROWS(array), , , 0)), array)),
        _join, VSTACK(_out, _fn(_row, array2)),
        _output, IF(ROWS(array1) = 1, DROP(_join, 1), CROSSJOIN(DROP(array1, 1), array2, _join)),
        _output
    )
);

/*
RANDOMDB creates a random array of combinations of items from each column in member_array
The resulting array has 'COLUMNS(member_array)' columns and 'rows' rows.

Author: Owen Price
Date: 2022-12-13
*/
RANDOMDB = LAMBDA(member_array, rows,
    LET(
        t, member_array,
        c, COLUMNS(t),
        IF(
            c = 1,
            "Not enough columns",
            LET(
                seq, SEQUENCE(c - 2, , 3),
                nonblank, LAMBDA(c, FILTER(INDEX(t, , c), INDEX(t, , c) <> "")),
                first, CROSSJOIN(nonblank(1), nonblank(2)),
                all, IF(c = 2, first, REDUCE(first, seq, LAMBDA(a, b, CROSSJOIN(a, nonblank(b))))),
                rand, CHOOSEROWS(all, RANDARRAY(rows, 1, 1, ROWS(all))),
                rand
            )
        )
    )
);