Question

> time1 = strptime("2010-03-01 00:15:00", format = "%Y-%m-%d %H:%M:%S")
> time2a = strptime("2010-03-01", format = "%Y-%m-%d")
> time2b = as.Date(time2a)
> difftime(time1, time2a)
Time difference of 15 mins
> difftime(time1, time2b)
Time difference of 5.25 hours

在difftime的帮助页面中，接受日期对象（time2b）。为什么结果错了（5.25小时）？

谢谢。

Answer 1

difftime做的第一件事就是检查tz参数。如果缺少它使用：

if(missing(tx)) {
    as.POSIXct(time1)
    as.POSIXct(time2)
}

测试：

> as.POSIXct(time2b)
[1] "2010-02-28 16:00:00 PST"
> as.POSIXct(time2a)
[1] "2010-03-01 PST"

因此它将我的时区偏移应用于date对象。

> difftime(time1,time2a)
Time difference of 15 mins
> difftime(time1,time2b,tz='GMT')
Time difference of 15 mins

difftime的结果不一致

1 个答案: