In R, aggregation is effected using the following command:
> goal_stats=read.csv('champ_league_stats_semifinalists.csv')
>goal_stats
Club Player Goals GamesPlayed
1 Atletico Madrid Diego Costa 8 9
2 Atletico Madrid ArdaTuran 4 9
3 Atletico Madrid RaúlGarcía 4 12
4 Atletico Madrid AdriánLópez 2 9
5 Atletico Madrid Diego Godín 2 10
6 Real Madrid Cristiano Ronaldo 17 11
7 Real Madrid Gareth Bale 6 12
8 Real Madrid Karim Benzema 5 11
9 Real Madrid Isco 3 12
10 Real Madrid Ángel Di María 3 11
11 Bayern Munich Thomas Müller 5 12
12 Bayern Munich ArjenRobben 4 10
13 Bayern Munich Mario Götze 3 11
14 Bayern Munich Bastian Schweinsteiger 3 8
15 Bayern Munich Mario Mandzukić 3 10
16 Chelsea Fernando Torres 4 9
17 Chelsea Demba Ba 3 6
18 Chelsea Samuel Eto'o 3 9
19 Chelsea Eden Hazard 2 9
20 Chelsea Ramires 2 10
We now compute the goals-per-game ratio for each striker, so as to measure their deadliness in front of goal:
>goal_stats$GoalsPerGame<- goal_stats$Goals/goal_stats$GamesPlayed
>goal_stats
Club Player Goals GamesPlayedGoalsPerGame
1 Atletico Madrid Diego Costa 8 9 0.8888889
2 Atletico Madrid ArdaTuran 4 9 0.4444444
3 Atletico Madrid RaúlGarcía 4 12 0.3333333
4 Atletico Madrid AdriánLópez 2 9 0.2222222
5 Atletico Madrid Diego Godín 2 10 0.2000000
6 Real Madrid Cristiano Ronaldo 17 11 1.5454545
7 Real Madrid Gareth Bale 6 12 0.5000000
8 Real Madrid Karim Benzema 5 11 0.4545455
9 Real Madrid Isco 3 12 0.2500000
10 Real Madrid Ángel Di María 3 11 0.2727273
11 Bayern Munich Thomas Müller 5 12 0.4166667
12 Bayern Munich ArjenRobben 4 10 0.4000000
13 Bayern Munich MarioGötze 3 11 0.2727273
14 Bayern Munich Bastian Schweinsteiger 3 8 0.3750000
15 Bayern Munich MarioMandzukić 3 10 0.3000000
16 Chelsea Fernando Torres 4 9 0.4444444
17 Chelsea Demba Ba 3 6 0.5000000
18 Chelsea Samuel Eto'o 3 9 0.3333333
19 Chelsea Eden Hazard 2 9 0.2222222
20 Chelsea Ramires 2 10 0.2000000
Suppose that we wanted to know the highest goals-per-game ratio for each team. We would calculate this as follows:
>aggregate(x=goal_stats[,c('GoalsPerGame')], by=list(goal_stats$Club),FUN=max)
Group.1 x
1 Atletico Madrid 0.8888889
2 Bayern Munich 0.4166667
3 Chelsea 0.5000000
4 Real Madrid 1.5454545
The tapply function is used to apply a function to a subset of an array or vector that is defined by one or more columns. The tapply function can also be used as follows:
>tapply(goal_stats$GoalsPerGame,goal_stats$Club,max)
Atletico Madrid Bayern Munich Chelsea Real Madrid
0.8888889 0.4166667 0.5000000 1.5454545