删除具有特定行顺序的观察答案

【问题标题】：Delete observations with specific row order删除具有特定行顺序的观察
【发布时间】：2020-03-10 02:00:36
【问题描述】：

我有一个来自游戏的基于活动的数据集，我想在游戏会话中汇总它。在某些情况下，我观察到游戏恢复后直接是游戏开始或游戏结束。由于这些不是有意义的游戏会话，因此我想从我的数据集中删除这些观察结果（每场比赛恢复后 a）比赛开始或 b）比赛结束。

简化示例数据：

game_da = data.frame(activity = c("gamestart", "activity1", "activity2", "gameclose", "gameresume", "gameclose", "gameresume", "activity1", "gameclose"))
game_da
    activity
1  gamestart
2  activity1
3  activity2
4  gameclose
5 gameresume
6  gameclose
7 gameresume
8  activity1
9  gameclose

预期输出：

game_da2 = data.frame(activity = c("gamestart", "activity1", "activity2", "gameclose", "gameresume", "activity1", "gameclose"))
game_da2
    activity
1  gamestart
2  activity1
3  activity2
4  gameclose
5 gameresume
6  activity1
7  gameclose

我尝试过的（...但删除了更多我想要的观察结果）：

game_da3 = mutate(game_da, help_var = case_when(  activity == "gameresume" |
+                                                   activity == "gamestart" |
+                                                   activity == "gameclose" ~ 1, TRUE ~ 0),
+                   lead_help_var = lead(help_var),
+                   diff_help_var = help_var + lead_help_var) %>%
+   filter(diff_help_var != 2)
game_da3
    activity help_var lead_help_var diff_help_var
1  gamestart        1             0             1
2  activity1        0             0             0
3  activity2        0             1             1
4 gameresume        1             0             1
5  activity1        0             1             1

【问题讨论】：

标签： r performance transform dplyr

【解决方案1】：

您可以使用lead 和lag 来过滤行：

library(dplyr)

game_da %>%
   filter(!(activity == 'gameresume' & 
            lead(activity, default = TRUE) %in% c('gameclose', 'gamestart') | 
            lag(activity, default = TRUE) == 'gameresume' & 
            activity %in% c('gameclose', 'gamestart')))

#    activity
#1  gamestart
#2  activity1
#3  activity2
#4  gameclose
#5 gameresume
#6  activity1
#7  gameclose

在data.table 和shift 中使用的类似逻辑

library(data.table)
setDT(game_da)[! (activity == 'gameresume' & 
   shift(activity, type = 'lead', fill = TRUE) %in% c('gameclose', 'gamestart') | 
   shift(activity, fill = TRUE) == 'gameresume' & 
         activity %in% c('gameclose', 'gamestart'))]

【讨论】：