我有一个数据集，我使用difftime来计算R中两次之间的差异。对于4天开始的记录，一天开始并持续到午夜，我得到了无意义的答案。
数据集
time2<-dput(time2)
structure(list(StationID = c(201707123L, 201710032L, 201710148L,
201710188L), TowStartTime = structure(c(-2209057289, -2209057558,
-2209057779, -2209057812), class = c("POSIXct", "POSIXt"), tzone = ""),
TowEndTime = structure(c(-2209142790, -2209143047, -2209143555,
-2209143587), class = c("POSIXct", "POSIXt"), tzone = ""),
tow_time = c(-1425.01666666667, -1424.81666666667, -1429.6,
-1429.58333333333)), .Names = c("StationID", "TowStartTime",
"TowEndTime", "tow_time"), row.names = c(572L, 783L, 1003L, 1079L
), class = "data.frame")
用于计算tow_tim的代码
time2$tow_time<-as.numeric(difftime(strptime(time2$TowEndTime,"%Y-%m-%d %H:%M:%S"),
strptime(time2$TowStartTime,"%Y-%m-%d %H:%M:%S")),units="mins")
我在开始时间前有结束时间因为我不想有负值。我得到了相同的时间差的答案，无论是哪种方式都不是负值。是否有办法考虑在午夜使用difftime或R中的其他功能来执行此操作？
答案 0 :(得分：0)
没有错误，在这种情况下，TowStartTime之后您有TowEndTime，因此tow_time将为负数。
示例：
StationID TowStartTime TowEndTime tow_time
572 201707123 1899-12-31 05:58:31 1899-12-30 06:13:30 -1425.017
在小时内你可以看到EndTime是startTime前的23小时：
-1425.017/60
[1] -23.75028
此输出没有错，可能是原始数据。 您的负时间戳是非常见日期的convertend：
as.POSIXct(-2209143587, origin="1970-01-01")
[1] "1899-12-30 06:00:13 CET"
答案 1 :(得分：0)
您可以考虑使用lubridate包中的interval函数。
然而，你的结束时间在你的开始时间之后仍然很奇怪。
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