r - 挣扎于如何组合数据框中的行组

Question

我有这样一个数据框

product_id view_count purchase_count
1           11         1   
2           20         3
3           5          2
...

例如，我想将其转换成一个表格，该表格按 view_count 分组并对一个时间间隔内的 purchase_count 求和。

view_count_range total_purchase_count
0-10                 45
10-20                65

这些 view_count_ranges 将具有固定大小。对于如何对这样的范围进行分组的任何建议，我将不胜感激。

Answer 1

cut 是处理这类事情的便捷工具。这是一种方法:

#First make some data to work with 
#I suggest you do this in the future as it makes it 
#easier to provide you with assistance.
set.seed(10)
dat <- data.frame(product_id=1:15, view_count=sample(1:20, 15, replace=T), 
    purchase_count=sample(1:8, 15, replace=T))
dat   #look at the data

#now we can use cut and aggregate by this new variable we just created
dat$view_count_range <- with(dat, cut(view_count, c(0, 10, 20)))
aggregate(purchase_count~view_count_range, dat, sum)

哪些 yield :

  view_count_range purchase_count
1           (0,10]             39
2          (10,20]             31