r - dplyr + group_by 并避免按字母顺序排序

Question

我有以下数据:

    data <- structure(list(user = c(1234L, 1234L, 1234L, 1234L, 1234L, 1234L, 
1234L, 1234L, 1234L, 1234L, 1234L, 4758L, 4758L, 9584L, 9584L, 
9584L, 9584L, 9584L, 9584L), time = c(1L, 2L, 3L, 4L, 5L, 6L, 
7L, 8L, 9L, 10L, 11L, 5L, 6L, 1L, 2L, 3L, 4L, 5L, 6L), fruit = structure(c(1L, 
6L, 1L, 1L, 6L, 5L, 5L, 3L, 4L, 1L, 2L, 4L, 2L, 1L, 6L, 5L, 5L, 
3L, 2L), .Label = c("apple", "banana", "lemon", "lime", "orange", 
"pear"), class = "factor"), count = c(1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), cum_sum = c(1L, 
2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 11L, 1L, 2L, 1L, 2L, 3L, 
4L, 5L, 6L)), .Names = c("user", "time", "fruit", "count", "cum_sum"
), row.names = c(NA, -19L), class = "data.frame")

对于这个集合中的每个用户，我想查看一段时间内水果的顺序。但是，有些水果是“背靠背”上市的。

   user time  fruit count cum_sum
1  1234    1  apple     1  1
2  1234    2   pear     1  2
3  1234    3  apple     1  3
4  1234    4  apple     1  4
5  1234    5   pear     1  5
6  1234    6 orange     1  6
7  1234    7 orange     1  7

我正在寻找的更多是用户按独特水果的时间序列。

问题是，如果我按用户和水果分组然后总结，dplyr 会自动按字母顺序对水果进行排序:

data %>% 
    group_by(user, fruit) %>%
    summarise(temp_var=1) %>%
    mutate(cum_sum = cumsum(temp_var))

我真正想要的是，对于上面的用户 1234(例如)，按照时间序列的顺序列出水果，但删除任何重复项。所以在我们看到苹果 > 梨 > 苹果 > 苹果 > 梨 > 橙 > 橙的地方，我们只会看到苹果 > 梨 > 苹果 > 梨 > 橙

Answer 1

所以使用 rleid最新功能 data.table CRAN 上的版本我们可以简单地做(虽然不确定您确切想要的输出)

library(data.table) ## v >= 1.9.6
res <- setDT(data)[, .(fruit = fruit[1L]), by = .(user, indx = rleid(fruit))
                    ][, cum_sum := seq_len(.N), by = user
                      ][, indx := NULL]
res
#     user  fruit cum_sum
#  1: 1234  apple       1
#  2: 1234   pear       2
#  3: 1234  apple       3
#  4: 1234   pear       4
#  5: 1234 orange       5
#  6: 1234  lemon       6
#  7: 1234   lime       7
#  8: 1234  apple       8
#  9: 1234 banana       9
# 10: 4758   lime       1
# 11: 4758 banana       2
# 12: 9584  apple       1
# 13: 9584   pear       2
# 14: 9584 orange       3
# 15: 9584  lemon       4
# 16: 9584 banana       5