Sets¶

Sets hold distinct non-null values in first-seen order: numbers compared exactly, items ignoring the eba_ prefix. They are written as literals ({1, 2}, {[eba_CU:EUR], [eba_CU:USD]}, the empty set {}), come from set parameters ({p_Allowed, set-item}), or are built with set_of(x) and the set operators union, intersect, setdiff and symdiff. In Python a set is a ValueSet.

from dpmxl import Item, MemoryProvider, Number, TableLayout, ValueSet, evaluate_rule

currencies = ValueSet.of([Item.parse("eba_CU:EUR"), Item.parse("eba_CU:USD")])
provider = MemoryProvider(
    [TableLayout("O", columns=("0010", "0020"), open_keys=("qEBB",))],
    {
        ("O", None, "0010", None, (("qEBB", "A"),)): Item.parse("eba_CU:EUR"),
        ("O", None, "0010", None, (("qEBB", "B"),)): Item.parse("eba_CU:JPY"),
        ("O", None, "0020", None, (("qEBB", "A"),)): Number.of(2, 0),
        ("O", None, "0020", None, (("qEBB", "B"),)): Number.of(3, 0),
    },
    parameters={"Allowed": currencies},
)


def show(expression):
    result = evaluate_rule(expression, provider)
    print(
        result.status, result.message or [outcome.passed for outcome in result.outcomes]
    )


print(ValueSet.of([1, 2, 2, None]))

ValueSet(members=(1, 2))

Membership with in¶

x in s tests each record of x against the set:

show("{tO, c0010} in {[eba_CU:EUR], [eba_CU:USD]}")
show("{tO, c0010} in {p_Allowed, set-item}")
show("{tO, c0010} in union({p_Allowed, set-item}, {[CU:JPY]})")

failed [True, False]
failed [True, False]
passed [True, True]

An operand of in or of a set operator that is not a set stands for the set of its non-null values, so {c0010} in {tT, r*, c0020} tests against the values of a column, and {tO, c0020} in setdiff({1, 2, 3}, {tO, c0020}) against what the column does not hold:

show("{tO, c0020} in setdiff({1, 2, 3}, {tO, c0020})")

failed [False, False]

Missing sets¶

A single null, such as a set parameter the report does not have, is a null set, which makes in and the set operators null. A default: {…} on the parameter supplies a set instead. set_of(null) is {}.

show("{tO, c0010} in {p_Missing, set-item}")
show("{tO, c0010} in {p_Missing, set-item, default: {[eba_CU:JPY]}}")

not_applicable [None, None]
failed [False, True]

Restrictions¶

Sets cannot be compared with = or the other comparison operators, and cannot be a rule's result. A set default on a cell selection is an error. The columnar evaluator handles in with a set literal; it hands every other set operand (parameters, selections, set operators) to the reference evaluator.

The language reference gives the syntax and examples of set literals, in and the set functions.