如果r中的值变为负值，则重置累积 [英] resetting cumsum if value goes to negative in r

问题描述

ve <- c(17, -9, 9, -17, 17, -17, 11, -9, 16, -18, 17, 0, 0, -18, 17, 0, 0, -17, 14, -14, 17, -2, 0, -15, 9, -9, 17, -16, 16, -17, 17, -17, 17, -17, 17, -17, 17, -8, 7, -16, 17, -14, 14, -10, 10, -16, 16, -10, 10, -12, 12, -11, 11, -17, 17, -17, 17, -9, 8, -17, 17, -17, 17, -16, 16, -17, 17, -8, 8, -9, 9, -17, 17, -17, 17, -13, 13, -10, 7, -10, 13, -16, 17, -13, 13, -13, 13, -9, 8, -17, 17, -10, 9, -17, 17, -17, 17, -16, 16, -10, 10, -15, 15, -14, 14, -14, 15, -13, 13, -9, 9, -13, 13, -12, 12, -10, 9, -11, 12, -8, 7, -10, 10, -9, 9, -11, 11, -9, 9, -7, 7, -12, 11, -11, 12, -11, 11, -14, 14, -13, 13, -10, 10, -13, 13, -17, 17, -7, 7, -17, 17, -17, 17, -14, 14, NA)

df <- data.frame(ve = ve, calc = 0)

我需要计算calc列中的总和，但需要将其重置为零，并在其值变为负数时重新开始。.
我已经尝试了几种条件，但实际上并没有工作。 ..

I need to calculate cumsum in column calc, but it needs to reset to zero and start again whenever its value goes negative.. I've tried several conditions but it's not really working...

还可以吗在dplyr中实现这一目标？我是dplyr的新手，每当需要使用依赖值时，都会发现有些困难。

Also, is it possible to achieve this in dplyr? I'm new to dplyr and find it somewhat difficult whenever I need to use dependent value..

感谢您的帮助！

应该按原样。

     ve calc
1    17    17
2    -9    8
3     9    17
4   -17    0
5    17    17
6   -17    0
7    11    11
8    -9    2
9    16    18
10  -18    0
11   17    17
12    0    17
13    0    17
14  -18    0
15   17    17

如果您看到第14行和第15行，则正常的总和为-1和16
但我希望它重置为0而不是-1并继续求和，因此下一个将是17

If you see row 14 and 15, with the normal cumsum it would be -1 and 16 but I want it to reset to 0 instead of -1 and continue cumsum, hence the next would be 17

推荐答案

替换 NA值为0，并使用 cumsum

We can replace the NA values with 0 and use cumsum

library(dplyr)
df1 <- df %>%
      group_by(grp = cumsum(lag(cumsum(replace(ve, is.na(ve), 0)) < 0, default = TRUE))) %>%
     mutate(calc = cumsum(replace(ve, is.na(ve), 0)), calc = replace(calc, calc < 0, 0)) %>%
      ungroup() %>%
      select(-grp)
head(df1, 15)
# A tibble: 15 x 2
#      ve  calc
#   <dbl> <dbl>
# 1    17    17
# 2    -9     8
# 3     9    17
# 4   -17     0
# 5    17    17
# 6   -17     0
# 7    11    11
# 8    -9     2
# 9    16    18
#10   -18     0
#11    17    17
#12     0    17
#13     0    17
#14   -18     0
#15    17    17

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