Goal Expectancy

Estimates the goal expectancy (the number of goals the bookmaker expects each team to score) based on their home, draw, away probabilities

import penaltyblog as pb
import pandas as pd

Get data from football-data.co.uk

fb = pb.scrapers.FootballData("ENG Premier League", "2019-2020")
df = fb.get_fixtures()

cols = ["team_home", "team_away", "psh", "psd", "psa"]
df = df[cols]

df.head()

	team_home	team_away	psh	psd	psa
id
1565308800---liverpool---norwich	Liverpool	Norwich	1.15	9.59	18.05
1565395200---bournemouth---sheffield_united	Bournemouth	Sheffield United	2.04	3.57	3.90
1565395200---burnley---southampton	Burnley	Southampton	2.71	3.31	2.81
1565395200---crystal_palace---everton	Crystal Palace	Everton	3.21	3.37	2.39
1565395200---tottenham---aston_villa	Tottenham	Aston Villa	1.30	5.84	10.96

Remove the overround from the odds

def remove_overround(row):
    odds = [
        row["psh"],
        row["psd"],
        row["psa"],
    ]

    odds = pb.implied.differential_margin_weighting(odds)

    return pd.Series(odds["implied_probabilities"])


df[["home", "draw", "away"]] = df.apply(remove_overround, axis=1)

df.head()

	team_home	team_away	psh	psd	psa	home	draw	away
id
1565308800---liverpool---norwich	Liverpool	Norwich	1.15	9.59	18.05	0.859818	0.094528	0.045654
1565395200---bournemouth---sheffield_united	Bournemouth	Sheffield United	2.04	3.57	3.90	0.481290	0.271206	0.247504
1565395200---burnley---southampton	Burnley	Southampton	2.71	3.31	2.81	0.360007	0.293118	0.346875
1565395200---crystal_palace---everton	Crystal Palace	Everton	3.21	3.37	2.39	0.302636	0.287845	0.409519
1565395200---tottenham---aston_villa	Tottenham	Aston Villa	1.30	5.84	10.96	0.758663	0.160665	0.080673

Get the goal expectancy

output = list()
for idx, row in df.head().iterrows():
    res = pb.models.goal_expectancy(row["home"], row["draw"], row["away"])

    tmp = {
        "team_home": row["team_home"],
        "team_away": row["team_away"],
        "home_expectancy": res["home_exp"],
        "away_expectancy": res["away_exp"],
        "success": res["success"],
        "error": res["error"],
    }

    output.append(tmp)

output = pd.DataFrame(output)
output

	team_home	team_away	home_expectancy	away_expectancy	success	error
0	Liverpool	Norwich	3.219933	0.667064	True	5.381587e-09
1	Bournemouth	Sheffield United	1.403588	0.923020	True	5.932409e-11
2	Burnley	Southampton	1.099876	1.073906	True	1.595460e-11
3	Crystal Palace	Everton	0.999968	1.213245	True	6.410602e-11
4	Tottenham	Aston Villa	2.312856	0.607438	True	1.123882e-10