r - 如何使用 R 计算产品的周数？

Question

我想按组计算封面产品的周数。我仍然是R的学习者下面是数据集

WK<-c('wk1','wk2','wk3','wk4','wk5','wk6','wk7','wk8','wk9','wk10','wk11','wk12')
Model<-c('AB','AB','AB','AB','AB','AB','AB','BC','BC','BC','BC','BC')
QTY<-c(100,200,300,400,500,600,800,500,230,500,600,900)
stock<-c(300,600,100,250,362,850,985,236,652,758,550,700)
df<-data.frame(WK,Model,QTY,stock)

'覆盖周'是根据库存(当前周)/平均值(接下来 4 周的数量)计算的。需要按模型计算所有周数。

预期结果

Answer 1

带有 slider 的选项

library(dplyr)
library(slider)
df %>% 
  mutate(cover = stock/lead(slide_dbl( QTY, .after = 3, .f = mean)))
 WK Model QTY stock     cover
1   wk1    AB 100   300 0.8571429
2   wk2    AB 200   600 1.3333333
3   wk3    AB 300   100 0.1739130
4   wk4    AB 400   250 0.4166667
5   wk5    AB 500   362 0.6798122
6   wk6    AB 600   850 1.6748768
7   wk7    AB 800   985 2.1530055
8   wk8    BC 500   236 0.4233184
9   wk9    BC 230   652 0.9780000
10 wk10    BC 500   758 1.0106667
11 wk11    BC 600   550 0.6111111
12 wk12    BC 900   700        NA