dplyr/R 带复位的累积总和 [英] dplyr / R cumulative sum with reset
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问题描述
如果当前"总和超过某个阈值,我想使用 dplyr 生成带有重置的累积总和.在下面,我想对 'a' 求和.
I'd like to generate cumulative sums with a reset if the "current" sum exceeds some threshold, using dplyr. In the below, I want to cumsum over 'a'.
library(dplyr)
library(tibble)
tib <- tibble(
t = c(1,2,3,4,5,6),
a = c(2,3,1,2,2,3)
)
# what I want
## thresh = 5
# A tibble: 6 x 4
# t a g c
# <dbl> <dbl> <int> <dbl>
# 1 1.00 2.00 0 2.00
# 2 2.00 3.00 0 5.00
# 3 3.00 1.00 1 1.00
# 4 4.00 2.00 1 3.00
# 5 5.00 2.00 1 5.00
# 6 6.00 3.00 2 3.00
# what I want
## thresh = 4
# A tibble: 6 x 4
# t a g c
# <dbl> <dbl> <int> <dbl>
# 1 1.00 2.00 0 2.00
# 2 2.00 3.00 0 5.00
# 3 3.00 1.00 1 1.00
# 4 4.00 2.00 1 3.00
# 5 5.00 2.00 1 5.00
# 6 6.00 3.00 2 3.00
# what I want
## thresh = 6
# A tibble: 6 x 4
# t a g c
# <dbl> <dbl> <int> <dbl>
# 1 1.00 2.00 0 2.00
# 2 2.00 3.00 0 5.00
# 3 3.00 1.00 0 6.00
# 4 4.00 2.00 1 2.00
# 5 5.00 2.00 1 4.00
# 6 6.00 3.00 1 7.00
我在这里检查了许多类似的问题(例如 如果 r 中的值变为负数,则重置 cumsum ) 并获得了我希望的结果,但没有.
I've examined many of the similar questions here (such as resetting cumsum if value goes to negative in r) and have gotten what I hoped was close, but no.
我尝试过
thresh <-5
tib %>%
group_by(g = cumsum(lag(cumsum(a) >= thresh, default = FALSE))) %>%
mutate(c = cumsum(a)) %>%
ungroup()
返回
# A tibble: 6 x 4
t a g c
<dbl> <dbl> <int> <dbl>
1 1.00 2.00 0 2.00
2 2.00 3.00 0 5.00
3 3.00 1.00 1 1.00
4 4.00 2.00 2 2.00
5 5.00 2.00 3 2.00
6 6.00 3.00 4 3.00
您可以看到组"在第一次之后没有被重置.
You can see that the "group" is not getting reset after the first time.
推荐答案
我想你可以在这里使用 accumulate()
来提供帮助.而且我还制作了一个包装函数来用于不同的阈值
I think you can use accumulate()
here to help. And i've also made a wrapper function to use for different thresholds
sum_reset_at <- function(thresh) {
function(x) {
accumulate(x, ~if_else(.x>=thresh, .y, .x+.y))
}
}
tib %>% mutate(c = sum_reset_at(5)(a))
# t a c
# <dbl> <dbl> <dbl>
# 1 1 2 2
# 2 2 3 5
# 3 3 1 1
# 4 4 2 3
# 5 5 2 5
# 6 6 3 3
tib %>% mutate(c = sum_reset_at(4)(a))
# t a c
# <dbl> <dbl> <dbl>
# 1 1 2 2
# 2 2 3 5
# 3 3 1 1
# 4 4 2 3
# 5 5 2 5
# 6 6 3 3
tib %>% mutate(c = sum_reset_at(6)(a))
# t a c
# <dbl> <dbl> <dbl>
# 1 1 2 2
# 2 2 3 5
# 3 3 1 6
# 4 4 2 2
# 5 5 2 4
# 6 6 3 7
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