blocks|key|659564|text|由于日期对应于一个数字值和一个开始日期，因此您确实需要日期。如果您确实需要日期格式的数据，您可以通过将日期粘贴到日期来手动将日期固定为每个月的第一天：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|659565|month+<-+"2009-03"
as.Date(paste(month,"-01",sep=""))|code-block|syntax|javascript|659566|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Since dates correspond to a numeric value and a starting date, you indeed need the day. If you really need your data to be in Date format, you can just fix the day to the first of each month manually by pasting it to the date:

<pre><code>month &lt;- "2009-03"
as.Date(paste(month,"-01",sep=""))
</code></pre>

blocks|key|876758|text|如果您需要日期格式，最简洁的解决方案是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|876759|library(zoo)
month+<-+"2000-03"
as.Date(as.yearmon(month))
[1]+"2000-03-01"|code-block|syntax|javascript|876760|as.Date会为你将每个月的第一天设置为一个年长的对象。|offset|length|style|CODE|876761|entityMap^0|0|0|0|7|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

The most concise solution if you need the dates to be in Date format:

<pre><code>library(zoo)
month &lt;- "2000-03"
as.Date(as.yearmon(month))
[1] "2000-03-01"
</code></pre>

<code>as.Date</code> will fix the first day of each month to a yearmon object for you.

blocks|key|659644|text|我认为@ben-rollert的解决方案是一个很好的解决方案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|659645|如果您想在新包内的函数中使用此解决方案，请务必小心。|659646|在开发包时，建议使用语法packagename::function_name()+(请参阅http://kbroman.org/pkg_primer/pages/depends.html)。|offset|length|style|CODE|659647|在这种情况下，您必须使用由zoo库定义的as.Date()版本。|659648|下面是一个示例：|659649|>+devtools::session_info()
Session+info+----------------------------------------------------------------------------------------------------------------------------------------------------
+setting++value+++++++++++++++++++++++
+version++R+version+3.3.1+(2016-06-21)
+system+++x86_64,+linux-gnu+++++++++++
+ui+++++++RStudio+(1.0.35)++++++++++++
+language+(EN)++++++++++++++++++++++++
+collate++C+++++++++++++++++++++++++++
+tz+++++++<NA>++++++++++++++++++++++++
+date+++++2016-11-09++++++++++++++++++

Packages+--------------------------------------------------------------------------------------------------------------------------------------------------------

+package++*+version+date+++++++source++++++++
+devtools+++1.12.0++2016-06-24+CRAN+(R+3.3.1)
+digest+++++0.6.10++2016-08-02+CRAN+(R+3.2.3)
+memoise++++1.0.0+++2016-01-29+CRAN+(R+3.2.3)
+withr++++++1.0.2+++2016-06-20+CRAN+(R+3.2.3)

>+as.Date(zoo::as.yearmon("1989-10",+"%25Y-%25m"))+
Error+in+as.Date.default(zoo::as.yearmon("1989-10",+"%25Y-%25m"))+:+
++do+not+know+how+to+convert+'zoo::as.yearmon("1989-10",+"%25Y-%25m")'+to+class+“Date”

>+zoo::as.Date(zoo::as.yearmon("1989-10",+"%25Y-%25m"))
[1]+"1989-10-01"|code-block|syntax|javascript|659650|因此，如果你正在开发一个包，最好的做法是使用：|659651|zoo::as.Date(zoo::as.yearmon("1989-10",+"%25Y-%25m"))|659652|entityMap|0|LINK|mutability|MUTABLE|url|http://kbroman.org/pkg_primer/pages/depends.html^0|0|0|C|S|19|1C|0|0|D|3|K|9|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|15|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|16|8|@$F|17|G|18|H|I]]|9|@$F|19|G|1A|1|1B]]|A|$]]|$1|J|3|K|5|6|7|1C|8|@$F|1D|G|1E|H|I]|$F|1F|G|1G|H|I]]|9|@]|A|$]]|$1|L|3|M|5|6|7|1H|8|@]|9|@]|A|$]]|$1|N|3|O|5|P|7|1I|8|@]|9|@]|A|$Q|R]]|$1|S|3|T|5|6|7|1J|8|@]|9|@]|A|$]]|$1|U|3|V|5|P|7|1K|8|@]|9|@]|A|$Q|R]]|$1|W|3|-4|5|6|7|1L|8|@]|9|@]|A|$]]]|X|$Y|$5|Z|10|11|A|$12|13]]]]

I think @ben-rollert's solution is a good solution. 

You just have to be careful if you want to use this solution in a function inside a new package. 

When developping packages, it's recommended to use the syntaxe <code>packagename::function_name()</code> (see <a href="http://kbroman.org/pkg_primer/pages/depends.html" rel="nofollow noreferrer">http://kbroman.org/pkg_primer/pages/depends.html</a>). 

In this case, you have to use the version of <code>as.Date()</code> defined by the <code>zoo</code> library. 

Here is an example : 

<pre><code>&gt; devtools::session_info()
Session info ----------------------------------------------------------------------------------------------------------------------------------------------------
 setting value 
 version R version 3.3.1 (2016-06-21)
 system x86_64, linux-gnu 
 ui RStudio (1.0.35) 
 language (EN) 
 collate C 
 tz &lt;NA&gt; 
 date 2016-11-09 

Packages --------------------------------------------------------------------------------------------------------------------------------------------------------

 package * version date source 
 devtools 1.12.0 2016-06-24 CRAN (R 3.3.1)
 digest 0.6.10 2016-08-02 CRAN (R 3.2.3)
 memoise 1.0.0 2016-01-29 CRAN (R 3.2.3)
 withr 1.0.2 2016-06-20 CRAN (R 3.2.3)

&gt; as.Date(zoo::as.yearmon("1989-10", "%Y-%m")) 
Error in as.Date.default(zoo::as.yearmon("1989-10", "%Y-%m")) : 
 do not know how to convert 'zoo::as.yearmon("1989-10", "%Y-%m")' to class “Date”

&gt; zoo::as.Date(zoo::as.yearmon("1989-10", "%Y-%m"))
[1] "1989-10-01"
</code></pre>

So if you're developping a package, the good practice is to use : 

<pre><code>zoo::as.Date(zoo::as.yearmon("1989-10", "%Y-%m"))
</code></pre>

blocks|key|876814|text|使用anytime包：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|876815|library(anytime)

anydate("2009-01")
#+[1]+"2009-01-01"|code-block|syntax|javascript|876816|entityMap|0|LINK|mutability|MUTABLE|url|https://cran.r-project.org/web/packages/anytime/index.html^0|2|7|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Using <a href="https://cran.r-project.org/web/packages/anytime/index.html" rel="noreferrer">anytime</a> package:

<pre><code>library(anytime)

anydate("2009-01")
# [1] "2009-01-01"
</code></pre>

I have a dataset that looks like this:

<pre><code>Month count
2009-01 12
2009-02 310
2009-03 2379
2009-04 234
2009-05 14
2009-08 1
2009-09 34
2009-10 2386
</code></pre>

I want to plot the data (months as x values and counts as y values). Since there are gaps in the data, I want to convert the Information for the Month into a date. I tried:

<pre><code>as.Date("2009-03", "%Y-%m")
</code></pre>

But it did not work. Whats wrong? It seems that as.Date() requires also a day and is not able to set a standard value for the day? Which function solves my problem?

Converting year and month ("yyyy-mm" format) to a date?

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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我有一个数据集，如下所示：Month    count2009-01  122009-02  3102009-03  23792009-04  2342009-05  142009-08  12009-09  342009-10  2386我想绘制数据(月份表示为x值，计数表示为y值)。由于数据中存在差距，因此我希望将...

问是否将年和月("yyyy-mm“格式)转换为日期？
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问是否将年和月("yyyy-mm“格式)转换为日期？
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