试图在R中的名称和产品中添加缺少的四分之一

我有一个类似于此示例的数据集，除了数千行不同的名称和产品之外：

Name <- c(rep("Tom",24),
      rep("Jake",8),
      rep("Jill",5))
Product <- c(rep("Orange",12),rep("Apples",12),
         rep("Orange",8),rep("Apples",5))
Quarter <- c("2013-03-31","2013-06-30","2013-09-30","2013-12-31",
         "2014-03-31","2014-06-30","2014-09-30","2014-12-31",
         "2015-03-31","2015-06-30","2015-09-30","2015-12-31",
         "2013-03-31","2013-06-30","2013-09-30","2013-12-31",
         "2014-03-31","2014-06-30","2014-09-30","2014-12-31",
         "2015-03-31","2015-06-30","2015-09-30","2015-12-31",
         "2013-12-31","2014-03-31","2014-06-30","2014-09-30",
         "2014-12-31","2015-03-31","2015-06-30","2015-09-30",
         "2014-09-30","2014-12-31","2015-03-31","2015-06-30",
         "2015-12-31")
sample <- cbind(Name,Product,Quarter)

---

Name首先，我们将
sample
转换为
data.frame

df <- data.frame(sample)

其中：

#Source: local data frame [48 x 3]
#
#     Name Product    Quarter
#   (fctr)  (fctr)     (fctr)
#1    Jake  Orange 2013-03-31
#2    Jake  Orange 2013-06-30
#3    Jake  Orange 2013-09-30
#4    Jake  Orange 2013-12-31
#5    Jake  Orange 2014-03-31
#6    Jake  Orange 2014-06-30
#7    Jake  Orange 2014-09-30
#8    Jake  Orange 2014-12-31
#9    Jake  Orange 2015-03-31
#10   Jake  Orange 2015-06-30
#..    ...     ...        ...

df <- data.frame(sample)

tidyr::expand(df, nesting(Name, Product), Quarter)

#Source: local data frame [48 x 3]
#
#     Name Product    Quarter
#   (fctr)  (fctr)     (fctr)
#1    Jake  Orange 2013-03-31
#2    Jake  Orange 2013-06-30
#3    Jake  Orange 2013-09-30
#4    Jake  Orange 2013-12-31
#5    Jake  Orange 2014-03-31
#6    Jake  Orange 2014-06-30
#7    Jake  Orange 2014-09-30
#8    Jake  Orange 2014-12-31
#9    Jake  Orange 2015-03-31
#10   Jake  Orange 2015-06-30
#..    ...     ...        ...