相关疑难解决方法(0)

我想了解rolling joins在data.table.最后给出了重现这一点的数据.

给出机场交易的数据表,在给定时间:

> dt
   t_id airport thisTime
1:    1       a      5.1
2:    3       a      5.1
3:    2       a      6.2  

(注t_ids1和3有相同的机场和时间)

以及从机场起飞的航班查询表:

> dt_lookup
   f_id airport thisTime
1:    1       a        6
2:    2       a        6
3:    1       b        7
4:    1       c        8
5:    2       d        7
6:    1       d        9
7:    2       e        8

> tables()
     NAME      NROW NCOL MB COLS                  KEY             
[1,] dt           3    3  1 t_id,airport,thisTime airport,thisTime
[2,] dt_lookup    7    3 …

背景

(问题不是必需的,但可能对阅读有用)

使用重复键在data.table上滚动连接

加入多个条件时的奇怪行为

数据

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), …