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How to find the sum by two factor columns in R?
To find the sum by two factor columns, we can use aggregate function. This is mostly required when we have frequency/count data for two factors. For example, if we have a data frame called df that contains two factor columns say f1 and f2 and one numerical column say Count then the sum of Count by f1 and f2 can be calculated by using the command aggregate(Count~f1+f2,data=df,sum).
Consider the below data frame −
x1<-sample(LETTERS[1:4],20,replace=TRUE) x2<-sample(letters[1:2],20,replace=TRUE) freq<-rpois(20,5) df1<-data.frame(x1,x2,freq) df1
x1 x2 freq 1 D b 4 2 C b 6 3 C b 7 4 A b 4 5 C b 4 6 C a 6 7 C b 2 8 C a 7 9 D b 4 10 D b 7 11 B a 3 12 B a 6 13 A a 5 14 B b 5 15 C a 2 16 B a 5 17 A b 6 18 B a 8 19 C a 2 20 D a 5
Finding sum of freq based on the combination of x1 and x2 −
x1 x2 freq 1 A a 5 2 B a 22 3 C a 17 4 D a 5 5 A b 10 6 B b 5 7 C b 19 8 D b 15
y1<-sample(c("hot","cold"),20,replace=TRUE) y2<-sample(c("Asia","America","Africa","Europe"),20,replace=TRUE) count<-sample(1:10,20,replace=TRUE) df2<-data.frame(y1,y2,count) df2
y1 y2 count 1 hot Africa 8 2 cold America 8 3 hot America 4 4 hot Africa 5 5 hot America 3 6 hot Europe 9 7 cold Asia 10 8 hot America 4 9 hot America 6 10 cold Africa 5 11 cold America 5 12 cold America 10 13 cold Africa 3 14 cold America 5 15 hot Asia 9 16 cold Asia 4 17 cold America 6 18 cold Europe 4 19 cold Africa 9 20 hot Africa 8
Finding sum of count based on the combination of y1 and y2 −
y1 y2 count 1 cold Africa 17 2 hot Africa 21 3 cold America 34 4 hot America 17 5 cold Asia 14 6 hot Asia 9 7 cold Europe 4 8 hot Europe 9
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