我正在与一个信用卡公司的采购小组合作，该小组分期进行了几次采购。我只拥有这些购买的总价值，但我想获得客户每月支付的实际价值。以下是一些示例数据：
library(data.table)
aa <- data.table('period' = c(1, 2, 3), 'customer' = 1, 'purchase' = c(90, 20, 10),
'installments' = c(3, 2, 1))
bb <- data.table('period' = c(1, 2, 3), 'customer' = 2, 'purchase' = c(50, 60, 10),
'installments' = c(2, 2, 1))
cc <- rbind(aa, bb)
period customer purchase installments
1: 1 1 100 3
2: 2 1 20 2
3: 3 1 10 1
4: 1 2 50 2
5: 2 2 60 2
6: 3 2 10 1
我想要的结果是：
period customer purchase installments spending
1: 1 1 90 3 30 (90/3)
2: 2 1 20 2 40 (90/3 + 20/2)
3: 3 1 10 1 50 (90/3 + 20/2 + 10)
4: 1 2 50 2 25 (50/2)
5: 2 2 60 2 55 (50/2 + 60/2)
6: 3 2 10 1 40 (60/2 + 10)
答案 0 :(得分：0)
我想我明白了
dt <- cc[rep(1:.N, installments)][, Indx := 1:.N, by = .(period, customer, installments)]
dt[, period := period + Indx - 1]
dt[, inst_pay := purchase/installments]
dt[, spending := sum(inst_pay), by = .(period, customer)]
setorder(dt, customer, period)
print(dt)
period customer purchase installments Indx inst_pay spending
1: 1 1 90 3 1 30 30
2: 2 1 90 3 2 30 40
3: 2 1 20 2 1 10 40
4: 3 1 90 3 3 30 50
5: 3 1 20 2 2 10 50
6: 3 1 10 1 1 10 50
7: 1 2 50 2 1 25 25
8: 2 2 50 2 2 25 55
9: 2 2 60 2 1 30 55
10: 3 2 60 2 2 30 40
11: 3 2 10 1 1 10 40