R data.table子组计数和组摘要的加权百分比

Question

我有以下数据表

n = 100000

DT = data.table(customer_ID = 1:n,
                married = rbinom(n, 1, 0.4),
                coupon = rbinom(n, 1, 0.15))

我需要创建一个表，该表汇总已婚和未婚客户的总数，使用优惠券的顾客数量（按婚姻状况子组），以及最后一列，用于按婚姻状况计算每个子组使用优惠券的顾客所占的百分比。

输出应如下所示。

   married Customers using Coupons Total Customers percent_usecoupon
1:       0                    9036           59790          15.11290
2:       1                    5943           40210          14.77991

我当前的代码效率很低，我敢肯定使用data.table会有更好的语法，但是我似乎找不到它。 我在下面复制了当前代码：

coupon_marital = DT[coupon == TRUE, .N, by = married][order(-N)] #Count of coupon use by marital status
total_marital = DT[, .N, by = married] #Total count by marital status
setnames(total_marital, "N", "Count") #Rename N to Count
coupon_marital = merge(coupon_marital, total_marital) #Merge data.tables

coupon_marital[, percent_usecoupon := N/Count*100, by = married] #Compute percentage coupon use
setnames(coupon_marital, c("N", "Count"), c("Customers using Coupons", "Total Customers")) #Rename N to Count
rm(total_marital)

print(coupon_marital)

我不能使用dplyr，而只需要使用data.table。 我对data.table语法非常陌生，非常感谢您的帮助！

Answer 1

建立资料

set.seed(10)
n = 100000
DT = data.table(customer_ID = 1:n,
                married = rbinom(n, 1, 0.4),
                coupon = rbinom(n, 1, 0.15))

汇总数据

DT[, .(N.UseCoupon   = sum(coupon)
      ,N.Total       = .N
      ,Pct.UseCoupon = 100*mean(coupon)), 
   by = married]

#    married N.UseCoupon N.Total Pct.UseCoupon
# 1:       0        8975   60223      14.90294
# 2:       1        5904   39777      14.84275