Function substitute_diminished_for_diminished

mingus/core/progressions.py:363–395

Substitute a diminished chord for another diminished chord. 'dim' and 'dim7' suffixes recognized, and 'VI' if there is no suffix. Example: >>> substitute_diminished_for_diminished(['VII'], 0) ['IIdim', 'bIVdim', 'bbVIdim']

(
    progression, substitute_index, ignore_suffix=False
)

def substitute_diminished_for_diminished(
    progression, substitute_index, ignore_suffix=False
):
    """Substitute a diminished chord for another diminished chord.

    'dim' and 'dim7' suffixes recognized, and 'VI' if there is no suffix.

    Example:
    >>> substitute_diminished_for_diminished(['VII'], 0)
    ['IIdim', 'bIVdim', 'bbVIdim']
    """
    (roman, acc, suff) = parse_string(progression[substitute_index])
    res = []

    # Diminished progressions
    if (
        suff == "dim7"
        or suff == "dim"
        or suff == ""
        and roman in ["VII"]
        or ignore_suffix
    ):
        if suff == "":
            suff = "dim"

        # Add diminished chord
        last = roman
        for x in range(3):
            next = skip(last, 2)
            acc += interval_diff(last, next, 3)
            res.append(tuple_to_string((next, acc, suff)))
            last = next
    return res


def substitute_diminished_for_dominant(