# FAQ: Aggregating Data - Let's Review

This community-built FAQ covers the “Let’s Review” exercise from the lesson “Aggregating Data”.

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I am slightly confused with the last task in the summary which is an analysis of FIFA 2022:

Calculate the Total Number of Goals by Each Team in the FIFA World Cup 2022.

Hint: We’ll need to combine each team’s goals scored as both the home team and away team.

1. Split `results` into a DataFrame containing only FIFA World Cup 2022 matches
• Combine multiple boolean masks using the `&` operator:
• `results['tournament']=='FIFA World Cup'`
• `results['year']== 2022`
• Perform a second split that creates separate DataFrames for home teams and away teams
1. Apply aggregation functions to each DataFrame that sums up the total number of goals scored by each team
• Don’t forget to flatten the index of the resulting aggregated DataFrames
1. Combine the two DataFrames by performing a left join where the DataFrame on the left contains the data for the home team (important!)
• Feel free to clean the column names but don’t drop the `home_team` and `away_team` columns!
• Create a new column `total_goals` that adds up the total goals scored by each team as the home team and away team
• Sort from highest to lowest number of `total_goals` by each team.

The code I’ve written for this task is below and I believe it adheres to the instructions but I am baffled by the table it produces. How should I be reading this table?

import pandas as pd import numpy as np results = pd.read_csv('results.csv') results.head() # Filter data for FIFA World Cup 2022 world_cup_2022 = results[(results['tournament'] == 'FIFA World Cup') & (results['year'] == 2022)] # Split into separate DataFrames for home and away teams home_teams = world_cup_2022[['home_team', 'home_score']] away_teams = world_cup_2022[['away_team', 'away_score']] # Aggregate goals for home and away teams home_goals = home_teams.groupby('home_team').agg(total_home_goals=('home_score', 'sum')).reset_index() away_goals = away_teams.groupby('away_team').agg(total_away_goals=('away_score', 'sum')).reset_index() # Join the two DataFrames combined_goals = pd.merge(home_goals, away_goals, left_on='home_team', right_on='away_team', how='left').fillna(0) # Calculate and sort total goals combined_goals['total_goals'] = combined_goals['total_home_goals'] + combined_goals['total_away_goals'] combined_goals = combined_goals.sort_values(by='total_goals', ascending=False) combined_goals = combined_goals.rename(columns={ 'home_team': 'team_1', 'away_team': 'team_2', 'total_home_goals': 'team_1_goals', 'total_away_goals': 'team_2_goals' }) combined_goals

I think you got it right. I got similar results.
team_1_goals are goals the team scored as the home team
team_2_goals are goals the team scored as the away team
the total_goals are all the goals the team scored during the FIFA 2022

Here’s how I did it. I cleaned up the output a little bit.

fifa = results['tournament'] == 'FIFA World Cup' year2022 = results['year'] == 2022 fifa2022 = results[fifa & year2022] home = fifa2022[['home_team', 'home_score']] away = fifa2022[['away_team', 'away_score']] home_total = home.groupby('home_team').agg({'home_score': 'sum'}).reset_index() away_total = away.groupby('away_team').agg({'away_score': 'sum'}).reset_index() combine = pd.merge( left = home_total, right = away_total, left_on = 'home_team', right_on = 'away_team', how = 'left') combine['away_score'] = combine['away_score'].fillna(0) sum_scores = combine['home_score'] + combine['away_score'] combine['total_score'] = sum_scores drop_columns = ['home_score', 'away_team', 'away_score'] clean = combine.drop( labels = drop_columns, axis = 1) clean = clean.rename(columns = {'home_team': 'team'}) clean = clean.sort_values(by = 'total_score', ascending = False) clean.reset_index(drop=True, inplace=True) print("FIFA World Cup 2022 Total Scores") clean