Expected-goals computation for NHL play-by-play data. Three XGBoost
models (5v5, special teams, penalty shots) are downloaded from
sportsdataverse/fastRhockey-nhl-data/main/models/ on package load
(see zzz.R's .onLoad()) and cached in
tools::R_user_dir("fastRhockey", "cache") so they're fetched once.
Details
Helpers
| Function | Purpose |
helper_nhl_prepare_xg_data() | Build the model feature frame (event filtering, era dummies, skater counts, rebound / rush / cross-ice flags). (internal) |
helper_nhl_calculate_xg() | Run the three XGBoost predictions and append an xg column to the PBP frame. |
Era dummies
The training corpus runs 2010-2024; the features keep one-hot era indicators so the same models generalize past the training cutoff:
| Indicator | Seasons |
era_2011_2013 | 20102011, 20112012, 20122013 |
era_2014_2018 | 20132014 ... 20172018 |
era_2019_2021 | 20182019, 20192020, 20202021 |
era_2022_2024 | 20212022, 20222023, 20232024 |
era_2025_on | seasons after 20232024 |
Required PBP columns
The input pbp data frame must include event_type, secondary_type,
period_type, period, game_seconds, x, y, x_fixed,
event_team_abbr, home_abbr, away_abbr, home_skaters,
away_skaters, shot_distance, shot_angle, empty_net,
strength_state, event_id, and season. nhl_game_pbp() /
nhl_game_feed() produce all of them.