dplyr: How to Add Cumulative Sums by Groups Into a Data Frame?
To add into a data frame, the cumulative sum of a variable by groups, the syntax is as follow using the dplyr package and the iris demo data set:
Output:
Code R :
library(dplyr) iris %>% group_by(Species) %>% mutate(cum_sep_len = cumsum(Sepal.Length))
Output:
# A tibble: 150 x 6
# Groups: Species [3]
Sepal.Length Sepal.Width Petal.Length Petal.Width Species cum_sep_len
1 5.1 3.5 1.4 0.2 setosa 5.1
2 4.9 3.0 1.4 0.2 setosa 10.0
3 4.7 3.2 1.3 0.2 setosa 14.7
4 4.6 3.1 1.5 0.2 setosa 19.3
5 5.0 3.6 1.4 0.2 setosa 24.3
6 5.4 3.9 1.7 0.4 setosa 29.7
7 4.6 3.4 1.4 0.3 setosa 34.3
8 5.0 3.4 1.5 0.2 setosa 39.3
9 4.4 2.9 1.4 0.2 setosa 43.7
10 4.9 3.1 1.5 0.1 setosa 48.6
# ... with 140 more rows