R: cumsum and group_by

Asked Apr 13 '21 at 19:08

Active Apr 13 '21 at 21:23

Viewed 103 times

I have the following sample data frame:

dates <- c("2021-01-01", "2021-01-03", "2021-01-06", "2021-01-02", "2021-01-04", "2021-01-06")
group <- c("A", "A", "A", "B", "B", "B")
values <- c(1, 5, 4, 2, 7, 3)

df <- data.frame(dates = as.Date(dates), group = group, values)
df

Can someone please tell me how I can compute a variable as the cumulated sum of values for each group (A and B) separately (+ chronologically)?

values_cumulated should be 1, 6, 10, 2, 9, 12

I was trying it with group_by() and mutate(values_cum = cumsum(values) ) but couldnt get it to work.

edited Apr 13 '21 at 19:10

asked Apr 13 '21 at 19:08

D. Studer

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Perhaps `df %>% arrange(group, as.Date(dates)) %>% group_by(group) %>% mutate(new = cumsum(values))` – akrun Apr 13 '21 at 19:10
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See the linked FAQ for how to sum by group - you can replace `sum` with `cumsum`. – Gregor Thomas Apr 13 '21 at 19:11

R: cumsum and group_by

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