跨 DST 日期的 XTS 时间子选择 Linux 与 Windows [英] XTS time subselect across DST date Linux vs Windows
问题描述
在 Windows 上,以下子选择代码生成不正确的 XTS 对象,但在我的 Ubuntu 机器上正常工作
On Windows the following subselect code produces an incorrect XTS object, but works correctly on my Ubuntu machine
library(xts)
theTimes <- seq(from=as.POSIXct('2016-03-10 12:00:00 CDT'),
to=as.POSIXct('2016-03-20 12:10:00 CDT'),by=60)
ExampleData <- xts(rep(1,length(theTimes)),theTimes)
CutExampleData <- ExampleData['T02:00/T16:00']
any(duplicated(index(CutExampleData))) ## Evaluates to TRUE on windows (incorrect) and FALSE on Ubuntu (correctly)
Linux PC 上的会话信息:
SessionInfo on Linux PC:
R version 3.3.1 (2016-06-21)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 16.04.1 LTS
locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8
[5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8 LC_PAPER=en_US.UTF-8 LC_NAME=C
[9] LC_ADDRESS=C LC_TELEPHONE=C LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] RMySQL_0.10.9 DBI_0.5-1 Quandl_2.8.0 xts_0.9-7 zoo_1.7-13
loaded via a namespace (and not attached):
[1] httr_1.2.1 R6_2.1.3 tools_3.3.1 grid_3.3.1 jsonlite_1.0 lattice_0.20-33
Windows PC 上的会话信息:
SessionInfo on Windows PC:
R version 3.3.2 (2016-10-31)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 14393)
locale:
[1] LC_COLLATE=English_United States.1252
[2] LC_CTYPE=English_United States.1252
[3] LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C
[5] LC_TIME=English_United States.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] xts_0.9-7 zoo_1.7-13
loaded via a namespace (and not attached):
[1] grid_3.3.2 lattice_0.20-34
我认为这与夏令时有关,因为索引跨越了最近的切换日期.有什么想法吗?
I think this has to do with DST, since the index spans the recent switch over date. Any ideas?
推荐答案
我能够在我的 Windows 机器上复制这个.在 R 的 *nix 和 Windows 版本之间,strptime
和/或 as.POSIXct.POSIXlt
看起来不正确.问题之所以出现是因为您的开始时间是 02:00:00,在 2016-03-13 不存在,因为由于夏令时,时间从美国/芝加哥时区的 01:59:59.999 到 03:00:00.
I was able to replicate this on my Windows machine. It looks like an infelicity in strptime
and/or as.POSIXct.POSIXlt
between *nix and Windows versions of R. The problem manifests because your start time is 02:00:00, which doesn't exist on 2016-03-13 because times go from 01:59:59.999 to 03:00:00 in the America/Chicago timezone due to daylight saving time.
一种解决方法是将您的开始时间设置为就在 02:00:00 之前.
A work-around is to set your start time to just before 02:00:00.
library(xts)
theTimes <- seq(from=as.POSIXct('2016-03-12 00:00:00', tz="America/Chicago"),
to=as.POSIXct('2016-03-14 23:00:00', tz="America/Chicago"), by=60)
ExampleData <- xts(rep(1,length(theTimes)),theTimes)
# 01:59 instead of 02:00 to avoid DST issue
CutExampleData <- ExampleData['T01:59/T16:00']
anyDuplicated(index(ExampleData))
anyDuplicated(index(CutExampleData)) # 0 (no duplicates)
另请注意,CDT"不是在 R 中指定时区的好方法.三个字母的时区缩写(GMT"和UTC"除外)可能不明确,因此最好使用 Region/城市规范.
Also note that "CDT" is not a good way to specify a timezone in R. The three-letter timezone abbreviations (aside from "GMT" and "UTC") may be ambiguous, so it's better to use the Region/City specification.
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