背景
(该问题不是必需的,但阅读可能有用)
具有重复键的 data.table 上的滚动联接 https://stackoverflow.com/q/32007115/4002530
连接多个条件时的奇怪行为 https://stackoverflow.com/q/32034222/4002530
Data
library(data.table) ## using version 1.9.6
## arrival timetable
dt_arrive <- structure(list(txn_id = c(1L, 1L, 1L, 1L, 1L), place = c("place_a",
"place_a", "place_a", "place_a", "place_a"), arrival_minutes = c(515,
534, 547, 561, 581), journey_id = 1:5), .Names = c("txn_id",
"place", "arrival_minutes", "journey_id"), class = c("data.table",
"data.frame"), row.names = c(NA, -5L), sorted = c("txn_id",
"place"))
## departure timetable
dt_depart <- structure(list(txn_id = c(1L, 1L, 1L, 1L), place = c("place_a",
"place_a", "place_a", "place_a"), arrival_minutes = c(489, 507,
519, 543), journey_id = 10:13), .Names = c("txn_id", "place",
"arrival_minutes", "journey_id"), sorted = c("txn_id", "place"
), class = c("data.table", "data.frame"), row.names = c(NA, -4L
))
> dt_arrive
txn_id place arrival_minutes journey_id
1: 1 place_a 515 1
2: 1 place_a 534 2
3: 1 place_a 547 3
4: 1 place_a 561 4
5: 1 place_a 581 5
> dt_depart
txn_id place arrival_minutes journey_id
1: 1 place_a 489 10
2: 1 place_a 507 11
3: 1 place_a 519 12
4: 1 place_a 543 13
Question
我想加入到达和出发的航班only those dt_depart$journey_id
发生的after dt_arrive$journey_id
按照arrival_minutes
(即内部联接txn_id
& place
)
例如,我想要的输出是:
txn_id place journey_in_id journey_out_id journey_place_arrive journey_place_depart
1 place_a 1 12 515 519
1 place_a 1 13 515 543
1 place_a 2 13 534 543
Attempts
使用我构建的两个链接问题中的方法
setkey(dt_arrive, txn_id, place)
setkey(dt_depart, txn_id, place)
dt_join <- dt_arrive[dt_depart,
{
idx = (i.arrival_minutes > arrival_minutes)
.(journey_in_id = journey_id[idx],
journey_out_id = i.journey_id,
journey_place_arrive = arrival_minutes[idx],
journey_place_depart = i.arrival_minutes
)
},
by=.EACHI]
但这给出了一切dt_depart
,所以包括NA
结果中的 s - 这表明“右连接”:
txn_id place journey_in_id journey_out_id journey_place_arrive journey_place_depart
1: 1 place_a NA 10 NA 489
2: 1 place_a NA 11 NA 507
3: 1 place_a 1 12 515 519
4: 1 place_a 1 13 515 543
5: 1 place_a 2 13 534 543
我尝试过使用nomatch=0
强制其“内部联接”,但这没有奏效。
我可以用complete.cases
删除NA
行,但我想知道是否有办法在查询本身中执行此操作?