def generate_conjuncts()

in rules/conjuncts.py [0:0]

• 51 lines of code
• 17 McCabe index (conditional complexity)

def generate_conjuncts(df: pd.DataFrame, target, predicates, beam_width):
    stats = ConfusionMatrix(df, target)
    num_pos = stats.pos_df.shape[0]
    num_total = df.shape[0]
    min_support = math.sqrt(num_pos) / num_total

    #beam and new_beam are mappings from rules to q_values
    beam = {}
    new_beam = {}

    for pred in predicates:
        r = Rule()
        r.add_conjunct(pred)
        q = r.eval(stats)
        beam[r] = q

    if beam_width > len(predicates):
        new_beam = beam.copy()
    else:
        values = sorted(beam.values(), reverse=True)
        cutoff = values[beam_width - 1]
        new_beam = {key: value for (key, value) in beam.items() if value >= cutoff}
        beam = new_beam.copy()

    i = 0
    while True:
        improved = False
        for rule in list(beam):
            for pred in predicates:
                if rule.check_useless(pred):
                    continue

                new_rule = Rule(rule)
                new_rule.add_conjunct(pred)

                if is_duplicate(new_rule, new_beam):
                    continue

                q = new_rule.eval(stats)
                num_tp = len(stats.true_positive(new_rule))
                exceeds_min_support = num_tp / df.shape[0] >= min_support
                if not exceeds_min_support:
                    continue

                (worst_rule, worst_q) = get_worst_rule(new_beam, beam_width)

                if q <= worst_q:
                    continue

                # TP(new_rule) < TP(existing) AND
                # FP(new_rule) > FP(existing)
                if is_irrelevant(new_rule, new_beam, stats):
                    continue
                if worst_q > 0:
                    new_beam.pop(worst_rule)
                new_beam[new_rule] = q
                improved = True

        if i == 0:
            clean_beam(new_beam)

        if not improved:
            break

        beam = new_beam
        i += 1
    return beam