How to sum a variable by group in R

+4 votes

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

 

Apr 13, 2018 in Data Analytics by Dynamic_Coder22
• 180 points
77,228 views
how could I use mutate in dplyr to add variable x into the dataframe

Hi, @Jackiechan,

mutate(): compute and add new variables into a data table. It preserves existing variables. Look at the below picture for better understanding.

Eg: my_data %>% mutate(data_frama, X = [existing_var])

I hope this will be helpful.

3 answers to this question.

0 votes

Easily by using Aggregate Func():


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

or By Using tapply:

tapply(x$points, x$Players, FUN=sum)
answered Apr 13, 2018 by CodingByHeart77
• 3,740 points

edited Apr 13, 2018 by CodingByHeart77
+1 vote

You can also try this way,

x_new = x %>% group_by(Players) %>% summarise(x = sum(points))

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answered Aug 1, 2019 by Cherukuri
• 33,030 points
The first operator, i.e., the one after x_new, should be <- not =.
0 votes

An advantage of the aggregate function is that it is already included in your Base R installation. Therefore we do not need to install any add-on packages.

The aggregate function can be used to calculate the summation of each group as follows.

aggregate(x = iris$Sepal.Length,               
          by = list(iris$Species),              
          FUN = sum) 
answered Dec 10, 2020 by MD
• 95,440 points

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