How to sum a variable by group in R?

Data Science

I have a data frame of consisting two columns "Players" & "points"

x<-data.frame(Players=c("Player1","Player2","Player3","Player2","Player3","Player1"),points=c(10,20,30,13,17,18))

Players points
1 Player1 10
2 Player2 20
3 Player3 30
4 Player2 13
5 Player3 17
6 Player1 18

I want to sort the data by players and sum the points:

Like this:

Players x
1 Player1 28
2 Player2 33
3 Player3 47

 


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2
Answers

Replies

One way to do this is to use tapply by summing the points with respect to players.



tapply(x$points, x$Players, FUN=sum)

 

You can use the aggregate function in the following way.



aggregate(x$points, by=list(Players=x$Players), FUN=sum)

 
 

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