Simple goals grid model

.GOALS_GRID.md

justin@justin-XPS-13-9360:~/work$ python3 goals_grid.py 
home_win	0.45395
away_win	0.24608
draw    	0.29997
over_05 	0.86466
under_05	0.13534
over_15 	0.59399
under_15	0.40601
over_25 	0.32332
under_25	0.67668
over_35 	0.14288
under_35	0.85712
over_45 	0.05265
under_45	0.94735
over_55 	0.01656
under_55	0.98344

goals_grid.py

import math

HomeWin, AwayWin, Draw = MatchOdds = ["home_win", "away_win", "draw"]

N=10

def poisson(l, x):
    return (l**x)*math.exp(-l)/math.factorial(x)

def correct_score_grid(lx, ly, rho, n):
    def DC_factor(i, j):
        if i==0 and j==0:
            return 1-lx*ly*rho
        elif i==0 and j==1:
            return 1+lx*rho
        elif i==1 and j==0:
            return 1+ly*rho
        elif i==1 and j==1:
            return 1-rho
        else:
            return 1
    return [[poisson(lx, i)*poisson(ly, j)*DC_factor(i, j)
             for j in range(n)]
            for i in range(n)]

class CSGrid(list):

    def __init__(self, data):
        list.__init__(self, data)

    def sum(self, filterfn):
        return sum([self[i][j]                    
                    for i in range(len(self))
                    for j in range(len(self))
                    if filterfn(i, j)])
                    
    def match_odds(self, selection):
        filterfns={HomeWin: lambda i, j: i > j,
                   AwayWin: lambda i, j: i < j,
                   Draw: lambda i, j: i==j}
        return self.sum(filterfns[selection])
    
    def over_goals(self, strike):        
        filterfn=lambda i, j: i+j > strike
        return self.sum(filterfn)
    
    def under_goals(self, strike):
        filterfn=lambda i, j: i+j < strike
        return self.sum(filterfn)

def run_model(lx, ly, rho, n=N):
    # initialise
    grid=CSGrid(correct_score_grid(lx, ly, rho, n))
    table=[]
    # match odds
    for attr in MatchOdds:
        value=grid.match_odds(attr)
        row={"name": attr,
             "value": value}
        table.append(row)
    # o/u goals
    for i in range(6):
        strike=i+0.5
        for attr in ["over", "under"]:
            name="%s_%s" % (attr, str(strike).replace(".", ""))
            fn=getattr(grid, "%s_goals" % attr)
            value=fn(strike)            
            row={"name": name,
                 "value": value}
            table.append(row)
    # return
    return table

if __name__=="__main__":
    def format_name(text, n=8):
        if len(text) > n:
            return text[:n]
        else:
            return text+" ".join(['' for i in range(1+n-len(text))])        
    for row in run_model(1.2, 0.8, 0):
        print ("%s\t%.5f" % (format_name(row["name"]),
                             row["value"]))