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Calculate expected goals (xG) for play-by-play data

Source: R/helpers_nhl.R
helper_nhl_calculate_xg.Rd

Adds an xg column to a play-by-play data frame using the fastRhockey xG models (XGBoost).

The models were trained on NHL PBP data from 2010-2024 using the same methodology as the hockeyR xG models. Three models are used:

  • 5v5 model — Even-strength situations

  • Special teams model — Power play, short-handed, and other non-5v5 situations (adds skater count features)

  • Penalty shot model — A constant xG value for penalty shot attempts

Models are loaded into the package namespace on package load via .onLoad() (see zzz.R).

Usage

helper_nhl_calculate_xg(pbp)

Arguments

pbp

A play-by-play data frame produced by nhl_game_pbp or nhl_game_feed. Must contain columns needed by helper_nhl_prepare_xg_data(): 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, season.

Value

The original pbp data frame with an xg column appended. xg is NA for non-shot events.

Examples

if (FALSE) { # \dontrun{
  pbp <- nhl_game_pbp(2024020001, include_shifts = TRUE)
  pbp <- helper_nhl_calculate_xg(pbp)
  # View xG for shots
  pbp[!is.na(pbp$xg), c("event_type", "shot_distance", "shot_angle", "xg")]
} # }