blocks|key|176469|text|MST和EST中的"S“代表”标准“。这总是非夏令储蓄的版本。你想在东部白天使用EDT。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|176470|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

The "S" in MST and EST stands for "standard." That's always the non-daylight savings version. You want to use EDT for eastern daylight time.

blocks|key|707486|text|这里有一条路。为了方便起见，我使用了anytime()+(来自任何时间包)|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|707487|R>+nyc+<-+format(anytime("12/05/2016+23:50",+tz="America/New_York"))
R>+phx+<-+format(anytime("12/05/2016+23:50",+tz="America/Phoenix"))
R>+diff(anytime(c(phx,+nyc)))
Time+difference+of+2+hours
R>+|code-block|syntax|javascript|707488|您必须通过显式文本表示(这是浪费的)，因为底层表示总是以UTC为单位：|707489|R>+difftime(anytime("12/05/2016+23:50",+tz="America/New_York"),
%2B+++++++++++anytime("12/05/2016+23:50",+tz="America/Phoenix"))
Time+difference+of+0+secs
R>+|707490|预期的/怀疑的三小时差只发生在夏天。使用七月而不是十二月：|707491|R>+phx+<-+format(anytime("07/05/2016+23:50",+tz="America/Phoenix"))
R>+nyc+<-+format(anytime("07/05/2016+23:50",+tz="America/New_York"))
R>+diff(anytime(c(phx,+nyc)))
Time+difference+of+3+hours
R>+|707492|当然，这里使用anytime()所做的一切都可以用Base函数来完成。这只是一条捷径，这一切都取决于POSIXt是如何处理这个问题的。|707493|编辑:我忘了在另一个包里有另一个助手：|707494|R>+RcppCCTZ::tzDiff("America/Phoenix",+"America/New_York",+anytime("2016-05-22"))
[1]+3
R>+|707495|entityMap|0|LINK|mutability|MUTABLE|url|https://cran.r-project.org/package=anytime^0|I|9|V|4|0|0|0|0|0|0|0|7|9|1E|6|0|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@$9|17|A|18|B|C]]|D|@$9|19|A|1A|1|1B]]|E|$]]|$1|F|3|G|5|H|7|1C|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1D|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|1E|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|1F|8|@]|D|@]|E|$]]|$1|Q|3|R|5|H|7|1G|8|@]|D|@]|E|$I|J]]|$1|S|3|T|5|6|7|1H|8|@$9|1I|A|1J|B|C]|$9|1K|A|1L|B|C]]|D|@]|E|$]]|$1|U|3|V|5|6|7|1M|8|@]|D|@]|E|$]]|$1|W|3|X|5|H|7|1N|8|@]|D|@]|E|$I|J]]|$1|Y|3|-4|5|6|7|1O|8|@]|D|@]|E|$]]]|Z|$10|$5|11|12|13|E|$14|15]]]]

Here is one way. I use <code>anytime()</code> for convenience (from the <a href="https://cran.r-project.org/package=anytime" rel="nofollow noreferrer">anytime</a> package)

<pre><code>R&gt; nyc &lt;- format(anytime("12/05/2016 23:50", tz="America/New_York"))
R&gt; phx &lt;- format(anytime("12/05/2016 23:50", tz="America/Phoenix"))
R&gt; diff(anytime(c(phx, nyc)))
Time difference of 2 hours
R&gt; 
</code></pre>

You have to go through explicit textual representation (which is wasteful) as the underlying representation is always in UTC:

<pre><code>R&gt; difftime(anytime("12/05/2016 23:50", tz="America/New_York"),
+ anytime("12/05/2016 23:50", tz="America/Phoenix"))
Time difference of 0 secs
R&gt; 
</code></pre>

The desired / suspected three hour difference occurs only in the summer. Using July instead of December:

<pre><code>R&gt; phx &lt;- format(anytime("07/05/2016 23:50", tz="America/Phoenix"))
R&gt; nyc &lt;- format(anytime("07/05/2016 23:50", tz="America/New_York"))
R&gt; diff(anytime(c(phx, nyc)))
Time difference of 3 hours
R&gt; 
</code></pre>

And of course, all that is done here with <code>anytime()</code> can be done with Base R functions. This is just a shortcut, and it all comes down to how <code>POSIXt</code> handles this.

Edit: I forgot that I have another helper in another package:

<pre><code>R&gt; RcppCCTZ::tzDiff("America/Phoenix", "America/New_York", anytime("2016-05-22"))
[1] 3
R&gt; 
</code></pre>

blocks|key|1894676|text|您有一个问题，因为EST。来自?timezone|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1894677|请注意，有些指定可能不是您所期望的:特别是EST是一个在加拿大使用的时区，没有夏令时。|blockquote|1894678|使用US/Eastern或America/New_York而不是EST。有关详细信息，请参阅?OlsonNames()。|1894679|#DST
x1+=+as.POSIXct("22/5/2016+23:50",+format+=+"%25d/%25m/%25Y+%25H:%25M",+tz+=+"America/New_York")
x2+=+as.POSIXct("22/5/2016+23:50",+format+=+"%25d/%25m/%25Y+%25H:%25M",+tz+=+"America/Phoenix")
x2+-+x1
#Time+difference+of+3+hours

#NOT+DST
x1+=+as.POSIXct("22/12/2016+23:50",+format+=+"%25d/%25m/%25Y+%25H:%25M",+tz+=+"America/New_York")
x2+=+as.POSIXct("22/12/2016+23:50",+format+=+"%25d/%25m/%25Y+%25H:%25M",+tz+=+"America/Phoenix")
x2+-+x1
#Time+difference+of+2+hours|code-block|syntax|javascript|1894680|entityMap^0|9|3|F|9|0|0|2|A|D|G|W|3|1A|D|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|W|8|@]|D|@]|E|$]]|$1|I|3|J|5|6|7|X|8|@$9|Y|A|Z|B|C]|$9|10|A|11|B|C]|$9|12|A|13|B|C]|$9|14|A|15|B|C]]|D|@]|E|$]]|$1|K|3|L|5|M|7|16|8|@]|D|@]|E|$N|O]]|$1|P|3|-4|5|6|7|17|8|@]|D|@]|E|$]]]|Q|$]]

You have a problem because of <code>EST</code>. From <code>?timezone</code>:

<blockquote>
 Beware that some of these designations may not be what you expect: in
 particular EST is a time zone used in Canada without daylight saving
 time...
</blockquote>

Use <code>US/Eastern</code> or <code>America/New_York</code> instead of <code>EST</code>. See <code>?OlsonNames()</code> for more information.

<pre><code>#DST
x1 = as.POSIXct("22/5/2016 23:50", format = "%d/%m/%Y %H:%M", tz = "America/New_York")
x2 = as.POSIXct("22/5/2016 23:50", format = "%d/%m/%Y %H:%M", tz = "America/Phoenix")
x2 - x1
#Time difference of 3 hours

#NOT DST
x1 = as.POSIXct("22/12/2016 23:50", format = "%d/%m/%Y %H:%M", tz = "America/New_York")
x2 = as.POSIXct("22/12/2016 23:50", format = "%d/%m/%Y %H:%M", tz = "America/Phoenix")
x2 - x1
#Time difference of 2 hours
</code></pre>

I want to calculate time differences between daylight saving time and non-daylight saving time. But I do not know how to let R know that a time is daylight saving time or not.

For example, Phoenix do not adjust daylight saving time in the summer, whereas most areas in US do. If I wanna calculate the time differences in the following, it's supposed to be 3 hours rather than 2 hours. 
tzone = "America/Phoenix" will automatically set the time as "MST", which is a daylight saving time, but this is not what I want.

<pre><code>library(lubridate)
x &lt;- "22/5/2016 23:50"
x &lt;- dmy_hm(x)
x1 &lt;- force_tz(x, tzone = "America/Phoenix")
x2 &lt;- force_tz(x, tzone = "EST")

x1-x2
# The output is "Time difference of 2 hours". But actually it is supposed to be 3 hours.
</code></pre>

I tried by setting tzone="EDT" or "MDT" to fix that. But it seems that R do not allow recognize those timezones.

<pre><code>&gt; x2 &lt;- force_tz(y, tzone = "EDT")
Warning messages:
1: In as.POSIXct.POSIXlt(lt) : unknown timezone 'EDT'
2: In as.POSIXlt.POSIXct(ct) : unknown timezone 'EDT'
&gt; x3 &lt;- force_tz(y, tzone = "MDT")
Warning messages:
1: In as.POSIXlt.POSIXct(x, tz) : unknown timezone 'EDT'
2: In as.POSIXct.POSIXlt(lt) : unknown timezone 'MDT'
3: In as.POSIXlt.POSIXct(ct) : unknown timezone 'MDT'
</code></pre>

Calculate time differences between daylight saving time and non-daylight saving time

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我想计算夏令时和非夏令时之间的时差。但我不知道如何让R知道一个时间是夏令时还是非夏令时。例如，凤凰城在夏季不调整夏令时间，而美国大部分地区则是这样。如果我想计算下面的时间差，应该是3小时，而不是2小时。tzone =“美国/凤凰”将自动将时间设置为"MST"，这是夏令时，但这不是我想要的。library(lubrida...

问计算夏令时与非夏令时的时差
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问计算夏令时与非夏令时的时差EN