Lineups

Lineup reconstruction combines boxscore starters with ordered substitution events.

Starting state

Exactly five unique starters are required for each team. Player IDs are sorted to form stable lineup keys; ordering within a five-player tuple has no tactical meaning.

Event-level assignments

event_lineups/{game_id}.parquet records:

• the home and away lineups before each event;
• the home and away lineups after each event;
• an optional atomic substitution batch ID.

For non-substitution events, before and after states are equal.

Atomic substitution batches

Consecutive substitution records form one batch. All outgoing and incoming players are applied together before the next basketball event.

This handles:

• both teams substituting at the same dead ball;
• source ordering that lists all outgoing players before incoming players;
• a player logged in and back out before play resumes, which becomes a net-zero change within the batch.

The resulting state must still contain exactly five unique players per team.

Lineup stints

lineup_stints/{game_id}.parquet contains intervals with stable five-on-five lineups. A stint starts at a period boundary or substitution and ends at a substitution, period end, or feed end.

Each stint stores:

• time and event boundaries;
• score boundaries and points by team;
• home and away player tuples;
• explicit start and end reasons.

Validation

Reconstructed player seconds are compared with boxscore minutes. Primary actors are checked against the lineup except for event classes where an on-court actor is not required, such as team or bench technical fouls.

Overtime periods use five-minute duration calculations and participate in the same stint and minute validations.