I would like to create a column called "tally" in my dataset that takes sums the count of each type and rank.
type <- c("A","A","A","B","B","C")
rank <- c("low", "med", "high","med", "high", "low")
count <- c(9,20,31,2,4,14)
df <- data.frame(type, rank, count)
My desired output would be:
type rank count tally
1 A low 9 9
2 A med 20 29
3 A high 31 60
4 B med 2 2
5 B high 4 6
6 C low 14 14
I guess another way to describe it would be a rolling sum (where it takes into account the low to high order)? I have looked around but I can't find any good functions to do this. Ideally, I could have a for loop that would allow me to get this "rolling sum" by type.
We can use cumsum after grouping by 'type'
library(dplyr)
df <- df %>%
group_by(type) %>%
mutate(tally = cumsum(count)) %>%
ungroup
-output
# A tibble: 6 x 4
type rank count tally
<chr> <chr> <dbl> <dbl>
1 A low 9 9
2 A med 20 29
3 A high 31 60
4 B med 2 2
5 B high 4 6
6 C low 14 14