将POSIXct日期时间转换为Date时出现意外日期-时区可以解决吗? [英] Unexpected date when converting POSIXct date-time to Date - can timezone fix it?
本文介绍了将POSIXct日期时间转换为Date时出现意外日期-时区可以解决吗?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
当我尝试使用强制将
,它似乎返回了错误的日期。 POSIXct
日期时间强制为 Date
时。日期
When I try to coerce a POSIXct
date-time to a Date
using as.Date
, it seems to return wrong date.
我怀疑它与时区有关。我在 as.Date
中尝试了 tz
参数,但没有给出预期的日期。
I suspect it has got something to do with the time zone. I tried the tz
argument in as.Date
, but it didn't give the expected date.
# POSIXct returns day of month 24
data$Time[3]
# [1] "2020-03-24 00:02:00 IST"
class(data$Time[3])
# [1] "POSIXct" "POSIXt"
# coerce to Date, returns 23
as.Date(data$Time[3])
# [1] "2020-03-23"
# try the time zone argument, without luck
as.Date(data$Time[3], tz = "IST")
# [1] "2020-03-23"
# Warning message:
# In as.POSIXlt.POSIXct(x, tz = tz) : unknown timezone 'IST'
Sys.timezone()
# [1] "Asia/Calcutta"
有什么想法在这里出问题吗?
Any ideas what may be going wrong here?
推荐答案
使用结尾处的注释中的设置,我们可以使用以下任意一种方法:
Using the setup in the Note at the end we can use any of these:
# same date as print(x) shows
as.Date(as.character(x))
## [1] "2020-03-24"
# use the time zone stored in x (or system time zone if that is "")
as.Date(x, tz = attr(x, "tzone"))
## [1] "2020-03-24"
# use system time zone
as.Date(x, tz = "")
## [1] "2020-03-24"
# use system time zone
as.Date(x, tz = Sys.timezone())
## [1] "2020-03-24"
# use indicated time zone
as.Date(x, tz = "Asia/Calcutta")
## [1] "2020-03-24"
注意
我们假设此设置。
Note
We have assumed this setup.
Sys.setenv(TZ = "Asia/Calcutta")
x <- structure(1584988320, class = c("POSIXct", "POSIXt"), tzone = "")
R.version.string
## [1] "R version 4.0.2 Patched (2020-06-24 r78745)"
这篇关于将POSIXct日期时间转换为Date时出现意外日期-时区可以解决吗?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文