Question

我有一个DF包含时间戳和相应的＆＃34;事件＆＃34; （两种类型的事件），另一种具有时间戳和事件类型确认。

我试图计算事件和确认事件的时间之间的时间。

可以立即或稍后（Tack>=Tevent）或永远收到致谢。如果没有相应的确认，我希望显示NA

的时差

示例：

dfEvent
Time      Event
00:00:01     A
00:01:00     B
00:05:00     A
00:09:00     B

dfAcknowledgement
Time      Event
00:00:02     A
00:05:10     A
00:09:05     B

RESULT
Time      Event   Delay
00:00:01     A    00:00:01
00:01:00     B    NA
00:05:00     A    00:00:10
00:09:00     B    00:00:05

我一直在关注data.table，但我并不想合并表：我想计算两个＆＃34;附近＆＃34;的价值之间的差异。行
我还在考虑使用which()来查找与确认相对应的事件的索引，但是一旦我获得了索引，如何在没有for循环的情况下从相应的行中减去它？

Answer 1

定义输入dfEvent和dfAcknowledgement，然后使用适当的键转换为data.table，同时计算NextTime。然后按Time执行data.tables的滚动连接，仅保留Time，Event和计算Delay。

library(data.table)
library(chron)

# test data from question
dfEvent <- data.frame(Time = c("00:00:01", "00:01:00", "00:05:00", "00:09:00"),
 Event = c("A", "B"), stringsAsFactors = FALSE)
dfAcknowledgement <- data.frame(Time = c("00:00:02", "00:05:10", "00:09:05"),
 Event = c("A", "A", "B"), stringsAsFactors = FALSE)

# convert to data.table (also compute NextTime column)
dtEvent <- with(dfEvent, data.table(Event = Event, Time = times(Time), 
                            NextTime = times(c(tail(Time, -1), NA)),
                            key = "Event,Time"))
dtAcknowledgement <- with(dfAcknowledgement, data.table(Event = Event, 
                            Time = times(Time), TimeAck = times(Time),
                            key = "Event,Time"))


# real work done here - perform rolling join, re-sort & compute desired columns
roll <- dtAcknowledgement[dtEvent,,roll=-Inf]
setkey(setkey(roll, NULL), Time, Event)
roll[, list(Time, Event, Delay = replace(TimeAck, TimeAck>=NextTime, NA)-Time)]

这给出了：

       Time Event    Delay
1: 00:00:01     A 00:00:01
2: 00:01:00     B     <NA>
3: 00:05:00     A 00:00:10
4: 00:09:00     B 00:00:05

匹配时间戳和计算时差（R）

1 个答案: