mahjong.hand_calculating.yaku

Abstract base for yaku pattern detection.

Defines the Yaku base class that every concrete yaku inherits. Each subclass represents one scoring pattern (e.g., tanyao, riichi, kokushi musou) and implements is_condition_met() to test whether the pattern is present in a given hand decomposition.

Concrete yaku are located in the yaku_list and yakuman packages.

class mahjong.hand_calculating.yaku.Yaku[source]

Bases: ABC

Abstract base class for all yaku.

Subclasses must set the class attributes below and implement is_condition_met(). A han value of 0 means the yaku is unavailable for that hand type (open or closed).

>>> from mahjong.hand_calculating.yaku_list import Iipeiko
>>> iipeiko = Iipeiko()
>>> iipeiko.yaku_id
14
>>> iipeiko.han_open
0
>>> iipeiko.han_closed
1
>>> iipeiko.is_yakuman
False
>>> str(iipeiko)
'Iipeiko'
Variables:

  • yaku_id (int) – unique numeric identifier for this yaku

  • name (str) – display name of the yaku (e.g., "Tanyao", "Kokushi Musou")

  • han_open (int) – han awarded when the hand is open; 0 if not available for open hands

  • han_closed (int) – han awarded when the hand is closed; 0 if not available for closed hands

  • is_yakuman (bool) – True for yakuman-level patterns (13+ han)

yaku_id: int

Unique numeric identifier for this yaku.

name: str

Display name of the yaku (e.g., "Tanyao", "Kokushi Musou").

han_open: int = 0

Han awarded for open hands. 0 means the yaku is not available when the hand is open.

han_closed: int = 0

Han awarded for closed hands. 0 means the yaku is not available when the hand is closed.

is_yakuman: bool = False

Whether this yaku is a yakuman (worth 13 han or more).

abstractmethod is_condition_met(hand, *args)[source]

Determine whether this yaku is present in the given hand decomposition.

The base signature accepts only the decomposed hand, but concrete subclasses may require additional positional arguments depending on the yaku. Common extra parameters include:

  • player_wind / round_wind — for yakuhai wind checks

  • win_tile, melds, is_tsumo — for yaku that depend on win conditions (e.g., san ankou, suu ankou)

  • tiles_34 — for kokushi, which uses the raw count array instead of a decomposed hand

Parameters:

  • hand (Collection[Sequence[int]]) – decomposed hand as a collection of tile groups in 34-format

  • args – additional attributes required by the specific yaku subclass

Returns:

True if the yaku condition is satisfied

Return type:

bool