R 基于现有列在数据框中创建新的累计列
我不久前创建了这个主题:基于现有列计算数据框中的新列。我现在正在寻找类似的东西,但有一点区别。一、 同样,请使用此数据集R 基于现有列在数据框中创建新的累计列,r,dataframe,dplyr,purrr,R,Dataframe,Dplyr,Purrr,我不久前创建了这个主题:基于现有列计算数据框中的新列。我现在正在寻找类似的东西,但有一点区别。一、 同样,请使用此数据集 df=tibble(article=rep("article one",5), week=c(1,2,3,4,5), sales=20, purchase=c(5,0,5,5,0), stock=c(50)) # A tibble: 5 x 5 article week sales purchase stock <chr&
df=tibble(article=rep("article one",5),
week=c(1,2,3,4,5),
sales=20,
purchase=c(5,0,5,5,0),
stock=c(50))
# A tibble: 5 x 5
article week sales purchase stock
<chr> <dbl> <dbl> <dbl> <dbl>
1 article one 1 20 5 50
2 article one 2 20 0 50
3 article one 3 20 5 50
4 article one 4 20 5 50
5 article one 5 20 0 50
我们可以使用
cumsum
和lag
library(dplyr)
df %>%
group_by(article) %>%
mutate(stock_over_time = lag(stock + cumsum(lead(purchase) - sales),
default = first(stock)),
stock_over_time = case_when(stock_over_time < 0
~ 0 - (sales * 1/4) + purchase, TRUE ~ stock_over_time)) %>%
ungroup
不过,这种逻辑是否适用于其他行?我不认为“第6行”会看到第5行计算的随时间变化的
stock\u
。我认为需要一个循环或类似于purr::acculate
的东西,因为每行的销售额取决于当时的库存状况。@JonSpring我也在用acculate
的方式思考。对于当前的示例,我认为,cumsum应该job@JonSpring我想更新应该可以解决你的问题mentioned@lucaskr使用accumulate
是可能的,但我认为for
循环会更容易、更简单readable@lucaskr我用Accumerate更新了解决方案在此之后您希望发生什么,例如,在“第6行”中?比如说,第5行的销售额增加了20,在0.25的降幅后减为5。如果stock\u over\u time
变成-5或-10?stock\u over\u time
会变成-10
50 - 20 + 0 = 30
30 - 20 + 5 = 15
15 - 20 + 5 = 0
0 - (20 * 1/4) + 0 = -5
library(dplyr)
df %>%
group_by(article) %>%
mutate(stock_over_time = lag(stock + cumsum(lead(purchase) - sales),
default = first(stock)),
stock_over_time = case_when(stock_over_time < 0
~ 0 - (sales * 1/4) + purchase, TRUE ~ stock_over_time)) %>%
ungroup
# A tibble: 5 x 6
# article week sales purchase stock stock_over_time
# <chr> <dbl> <dbl> <dbl> <dbl> <dbl>
#1 article one 1 20 5 50 50
#2 article one 2 20 0 50 30
#3 article one 3 20 5 50 15
#4 article one 4 20 5 50 0
#5 article one 5 20 0 50 -5
f1 <- function(dat) {
dat$stock_over_time <- NA_real_
dat$stock_over_time[1] <- dat$stock[1]
for(i in 2:nrow(dat)) {
dat$stock_over_time[i] <- dat$stock_over_time[i-1] -
dat$sales[i] + dat$purchase[i]
if(dat$stock_over_time[i] < 0 ) {
dat$stock_over_time[i] <- dat$stock_over_time[i-1] -
(dat$sales[i]* 1/4) + dat$purchase[i]
}
}
return(dat)
}
unsplit(lapply(split(df, df$article), f1), df$article)
# A tibble: 5 x 6
# article week sales purchase stock stock_over_time
# <chr> <dbl> <dbl> <dbl> <dbl> <dbl>
#1 article one 1 20 5 50 50
#2 article one 2 20 0 50 30
#3 article one 3 20 5 50 15
#4 article one 4 20 5 50 0
#5 article one 5 20 0 50 -5
library(purrr)
f1 <- function(x, y, z) {
tmp <- x - y + z
if(tmp < 0) {
tmp <- x - (y* 1/4) + z
}
return(tmp)
}
}
df %>%
group_by(article) %>%
mutate(stock_over_time = accumulate2(sales,
lead(purchase, default = last(purchase)), f1, .init = first(stock)) %>%
flatten_dbl() %>%
head(-1)) %>%
ungroup
# A tibble: 5 x 6
# article week sales purchase stock stock_over_time
# <chr> <dbl> <dbl> <dbl> <dbl> <dbl>
#1 article one 1 20 5 50 50
#2 article one 2 20 0 50 30
#3 article one 3 20 5 50 15
#4 article one 4 20 5 50 0
#5 article one 5 20 0 50 -5