r - 试图与 POSIXct 时间间隔相交，但得到 NA 结果

Question

我试图找到重叠时间的持续时间。我知道我的代码很接近，但是当我尝试使用 intersect 函数时得到 NA 结果。我希望有人能帮我看看我哪里出错了。

我已经遵循了这里的大部分示例R 时间段重叠- 但并没有完全正确。我想我一定漏掉了一个细节......

library(data.table)
library(lubridate)

首先，我创建了 2 个时间段重叠的数据表

#create data table with observation shifts
start <- as.POSIXct(c("2017-08-01 04:52:00", "2017-08-01 05:56:00", "2017-08-01 13:25:00", "2017-08-01 13:50:00", "2017-08-01 14:29:00", "2017-08-01 15:28:00", "2017-08-01 15:57:00", "2017-08-01 17:22:00", "2017-08-01 17:37:00", "2017-08-01 19:10:00", "2017-08-01 22:52:00", "2017-08-02 04:00:00", "2017-08-02 05:02:00", "2017-08-02 08:47:00", "2017-08-02 13:31:00", "2017-08-02 18:13:00", "2017-08-03 04:31:00", "2017-08-03 05:34:00", "2017-08-03 07:20:00", "2017-08-03 08:25:00", "2017-08-03 09:33:00", "2017-08-03 12:20:00", "2017-08-03 14:04:00", "2017-08-03 21:21:00", "2017-08-07 18:22:00", "2017-08-08 10:20:00", "2017-08-08 14:05:00", "2017-08-08 15:57:00", "2017-08-08 17:01:00", "2017-08-09 04:27:00"),  format = "%Y-%m-%d %H:%M:%S", tz = "America/Halifax")
end <- as.POSIXct(c("2017-08-01 05:03:00", "2017-08-01 12:22:00", "2017-08-01 13:31:00", "2017-08-01 13:59:00",
"2017-08-01 15:23:00", "2017-08-01 15:56:00", "2017-08-01 17:21:00", "2017-08-01 17:35:00","2017-08-01 19:08:00", "2017-08-01 22:51:00", "2017-08-02 00:00:00", "2017-08-02 04:59:00", "2017-08-02 08:41:00","2017-08-02 13:27:00", "2017-08-02 17:45:00", "2017-08-03 00:02:00", "2017-08-03 05:32:00", "2017-08-03 07:18:00", "2017-08-03 08:24:00", "2017-08-03 09:27:00", "2017-08-03 11:59:00", "2017-08-03 13:54:00", "2017-08-03 16:20:00", "2017-08-04 00:01:00",
"2017-08-07 20:03:00", "2017-08-08 14:04:00", "2017-08-08 14:40:00", "2017-08-08 16:57:00", "2017-08-09 00:02:00", "2017-08-09 05:09:00"),  format = "%Y-%m-%d %H:%M:%S", tz = "America/Halifax")
effort <- data.table(start, end)

#create data table with daylight hours
day.start = seq.POSIXt(as.POSIXct("2017-07-31 05:30:00", 
                                  format = "%Y-%m-%d %H:%M:%S",
                                  tz = "America/Halifax"),
                       as.POSIXct("2017-08-23 05:30:00", 
                                  format = "%Y-%m-%d %H:%M:%S",
                                  tz = "America/Halifax"),by = "day")
day.end = seq.POSIXt(as.POSIXct("2017-07-31 20:00:00", 
                                format = "%Y-%m-%d %H:%M:%S",
                                tz = "America/Halifax"),
                     as.POSIXct("2017-08-23 20:00:00", 
                                format = "%Y-%m-%d %H:%M:%S",
                                tz = "America/Halifax"),by = "day")
daytimes = data.table(day.start, day.end)

现在找到重叠发生的位置

#get ready to do foverlaps
setkey(effort, start, end)
setkey(daytimes, day.start, day.end)

#find overlapping periods
ov = foverlaps(daytimes,effort,type="any",nomatch=0)
# calculate intervals for effort daylight time periods that overlap
ov$int_eff = interval(ov$start, ov$end)
ov$int_day = interval(ov$day.start, ov$day.end)
# what time period is in common for each overlap?

到目前为止，一切似乎都很好。但是当我试图找到交叉点时，我最终得到了一系列 NA 值

ov$int_o = intersect(ov$int_eff, ov$int_day)
# take a look to check
head(ov$int_o)

编辑 - 现在包括预期的输出。

找到交叉点后，我会计算持续时间，然后总结它们。对于此示例，总持续时间为 46 小时。

# now calculate durations of intersect intervals
ov$dur = as.duration(ov$int_o)
round(sum(ov$dur/dhours(1), na.rm=T), 1)

标签： rlubridateposixctintersect