I am trying to create a rating data frame for some football teams. To rate the teams I am using elo rating system :
https://en.wikipedia.org/wiki/Elo_rating_system
My data frame consists of pre-match ratings of home and away teams and it gets updated after every match.
My data frame code is:
for index in df.index:
counter = counter + 1
if df.at[index,'updated'] == 2:
try:
all_home_fixtures = df.date_rank[df['localteam_id'] == df.at[index,'localteam_id']]
next_home_fixture =all_home_fixtures[all_home_fixtures>df.at[index,'date_rank']].min()
next_home_index = df[(df['date_rank'] == next_home_fixture) & (df['localteam_id'] == df.at[index,'localteam_id'])].index.item()
except ValueError:
print('ERROR 1 at' + str(index))
df.at[index,'updated'] = 4
try:
all_away_fixtures = df.date_rank[df['visitorteam_id'] == df.at[index,'visitorteam_id']]
next_away_fixture = all_away_fixtures[all_away_fixtures > df.at[index,'date_rank']].min()
next_away_index = df[(df['date_rank'] == next_away_fixture) & (df['visitorteam_id'] == df.at[index,'visitorteam_id'])].index.item()
except ValueError:
print('ERROR 2 at' + str(index))
df.at[index,'updated'] = 4
str(df.at[index,'date_rank']) + '; Next home date rank: ' + str(df.at[next_home_index,'date_rank']) + '; Next away date rank: ' + str(df.at[next_away_index,'date_rank']))
df.at[next_home_index, 'home_elo'] = update_elo(df.at[index,'home_elo'],df.at[index,'away_elo'],df.at[index,'actual_score'])
df.at[next_away_index, 'away_elo'] = update_elo(df.at[index,'away_elo'],df.at[index,'home_elo'],1 - df.at[index,'actual_score']) # Swap function inputs for away team
df.at[next_home_index, 'updated'] = df.at[next_home_index, 'updated'] + 1
df.at[next_away_index, 'updated'] = df.at[next_away_index, 'updated'] + 1
df.at[index,'updated'] = 3
But after working in some of the rows it gives me an error like :
ValueError: can only convert an array of size 1 to a python scalar
Can any one help me to find what the problem really is and help me to solve the problem.