blocks|key|3026942|text|这是一个有趣的问题，这样的类还不存在似乎很奇怪(re+@joel+Cornett+comment)如果你只在年份工作，它会简化你的类来处理整数而不是日历日期-你可以使用一个字典，其中包含文本描述(公元前10年)和整数值(-10)编辑:我谷歌了一下：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3026943|http://code.activestate.com/lists/python-list/623672/|offset|length|3026944|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|1H|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@$D|O|E|P|1|Q]]|A|$]]|$1|F|3|-4|5|6|7|R|8|@]|9|@]|A|$]]]|G|$H|$5|I|J|K|A|$L|C]]]]

Its an interesting question, it seems odd that such a class does not exist yet (re @joel Cornett comment) If you only work in years only it would simplify your class to handling integers rather than calendar dates - you could possibly use a dictionary with the text description (10 BC) against and integer value (-10)
EDIT: I googled this:

<a href="http://code.activestate.com/lists/python-list/623672/" rel="nofollow">http://code.activestate.com/lists/python-list/623672/</a>

blocks|key|191821|text|天文学家和航空航天工程师必须处理公元前的日期和连续的时间线，所以这就是你搜索的谷歌上下文。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|191822|Astropy的Time类将为您工作(甚至比您期望的更精确、更完整)。pip+install+astropy，您就可以上路了。|offset|length|style|CODE|191823|如果您使用自己的公式，则应该复习Vallado's+chapter+on+dates中的一些公式。要将日期从朱利安转换为公历等，需要使用许多模糊的因子。|191824|entityMap|0|LINK|mutability|MUTABLE|url|http://www.astropy.org/|1|http://docs.astropy.org/en/stable/api/astropy.time.Time.html|2|https://rads.stackoverflow.com/amzn/click/com/1881883140^0|0|8|4|Z|J|0|7|0|8|4|1|0|G|Q|2|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|W|8|@$D|X|E|Y|F|G]|$D|Z|E|10|F|G]]|9|@$D|11|E|12|1|13]|$D|14|E|15|1|16]]|A|$]]|$1|H|3|I|5|6|7|17|8|@]|9|@$D|18|E|19|1|1A]]|A|$]]|$1|J|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|K|$L|$5|M|N|O|A|$P|Q]]|R|$5|M|N|O|A|$P|S]]|T|$5|M|N|O|A|$P|U]]]]

Astronomers and aerospace engineers have to deal with BC dates and a continuous time line, so that's the google context for your search. 

<a href="http://www.astropy.org/" rel="noreferrer">Astropy</a>'s <a href="http://docs.astropy.org/en/stable/api/astropy.time.Time.html" rel="noreferrer"><code>Time</code></a> class will work for you (and even more precisely and completely than you hoped). <code>pip install astropy</code> and you're on your way.

If you roll your own, you should review some of the formulas in <a href="https://rads.stackoverflow.com/amzn/click/com/1881883140" rel="noreferrer" rel="nofollow noreferrer">Vallado's chapter on dates</a>. There are lots of obscure fudge factors required to convert dates from Julian to Gregorian etc.

blocks|key|2814431|text|这是一个老问题，但我也有同样的问题，并找到了this+article+announcing+datautil，它设计用于处理日期，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2814432|2814433|blockquote|2814434|2814435|2814436|日期在遥远的过去和将来，包括BC/BCE日期和各种格式的|unordered-list-item|2814437|日期:1890年1月，1890年1月，1890年12月1日，1890年春季等不同精度的|2814438|日期:例如1890年，1890-01+(即1890年1月)，1890-01-02|2814439|Imprecise日期:+c1890,1890?，fl+1890等|2814440|2814441|安装只是|2814442|pip+install+datautil|style|CODE|2814443|到目前为止，我只研究了几分钟，但注意到它不接受str作为参数(只接受unicode)，而且它实现了自己的date类(Flexidate，“ISO8601的一个略微扩展的版本”)，这可能是有用的。|2814444|>>>+from+datautil.date+import+parse
>>>+parse('Jan+1890')

error:+'str'+object+has+no+attribute+'read'

>>>+fd+=+parse(u'Jan+1890')
<class+'datautil.date.FlexiDate'>+1890-01

fd.as_datetime()
>>>+datetime.datetime(1890,+1,+1,+0,+0)

>>>+bc+=+parse(u'2000BC')
<class+'datautil.date.FlexiDate'>+-2000|code-block|syntax|javascript|2814445|但可惜的是...|2814446|>>>+bc.as_datetime()
ValueError:+year+is+out+of+range|2814447|不幸的是，对我来说，我正在寻找一个可以处理日期与"circa“(c，ca，ca，circ。或cca。)|2814448|>>>+ca+=+parse(u'ca+1900')
<class+'datautil.date.FlexiDate'>++[UNPARSED:+ca+1900]|2814449|哦，好吧-我想我总是可以发送一个拉取请求;-)|2814450|entityMap|0|LINK|mutability|MUTABLE|url|http://rufuspollock.org/2009/06/18/flexible-dates-in-python/|1|http://en.wikipedia.org/wiki/Circa^0|M|W|0|0|0|0|0|0|0|0|0|0|0|0|0|K|0|0|0|0|0|P|5|1|0|0|0^^$0|@$1|2|3|4|5|6|7|1P|8|@]|9|@$A|1Q|B|1R|1|1S]]|C|$]]|$1|D|3|-4|5|6|7|1T|8|@]|9|@]|C|$]]|$1|E|3|-4|5|F|7|1U|8|@]|9|@]|C|$]]|$1|G|3|-4|5|6|7|1V|8|@]|9|@]|C|$]]|$1|H|3|-4|5|6|7|1W|8|@]|9|@]|C|$]]|$1|I|3|J|5|K|7|1X|8|@]|9|@]|C|$]]|$1|L|3|M|5|K|7|1Y|8|@]|9|@]|C|$]]|$1|N|3|O|5|K|7|1Z|8|@]|9|@]|C|$]]|$1|P|3|Q|5|K|7|20|8|@]|9|@]|C|$]]|$1|R|3|-4|5|6|7|21|8|@]|9|@]|C|$]]|$1|S|3|T|5|6|7|22|8|@]|9|@]|C|$]]|$1|U|3|V|5|6|7|23|8|@$A|24|B|25|W|X]]|9|@]|C|$]]|$1|Y|3|Z|5|6|7|26|8|@]|9|@]|C|$]]|$1|10|3|11|5|12|7|27|8|@]|9|@]|C|$13|14]]|$1|15|3|16|5|6|7|28|8|@]|9|@]|C|$]]|$1|17|3|18|5|12|7|29|8|@]|9|@]|C|$13|14]]|$1|19|3|1A|5|6|7|2A|8|@]|9|@$A|2B|B|2C|1|2D]]|C|$]]|$1|1B|3|1C|5|12|7|2E|8|@]|9|@]|C|$13|14]]|$1|1D|3|1E|5|6|7|2F|8|@]|9|@]|C|$]]|$1|1F|3|-4|5|6|7|2G|8|@]|9|@]|C|$]]]|1G|$1H|$5|1I|1J|1K|C|$1L|1M]]|1N|$5|1I|1J|1K|C|$1L|1O]]]]

This is an old question, but I had the same one and found <a href="http://rufuspollock.org/2009/06/18/flexible-dates-in-python/" rel="nofollow">this article announcing datautil</a>, which is designed to handle dates like:

<blockquote>
 <ul>
 <li>Dates in distant past and future including BC/BCE dates</li>
 <li>Dates in a wild variety of formats: Jan 1890, January 1890, 1st Dec 1890, Spring 1890 etc</li>
 <li>Dates of varying precision: e.g. 1890, 1890-01 (i.e. Jan 1890), 1890-01-02</li>
 <li>Imprecise dates: c1890, 1890?, fl 1890 etc</li>
 </ul>
</blockquote>

Install is just

<code>pip install datautil</code>

I explored it for only a few minutesso far, but have noted that it doesn't accept str as an argument (only unicode) and it implements its own date class (Flexidate, 'a slightly extended version of ISO8601'), which is sort of useful maybe. 

<pre><code>&gt;&gt;&gt; from datautil.date import parse
&gt;&gt;&gt; parse('Jan 1890')

error: 'str' object has no attribute 'read'

&gt;&gt;&gt; fd = parse(u'Jan 1890')
&lt;class 'datautil.date.FlexiDate'&gt; 1890-01

fd.as_datetime()
&gt;&gt;&gt; datetime.datetime(1890, 1, 1, 0, 0)

&gt;&gt;&gt; bc = parse(u'2000BC')
&lt;class 'datautil.date.FlexiDate'&gt; -2000
</code></pre>

but alas...

<pre><code>&gt;&gt;&gt; bc.as_datetime()
ValueError: year is out of range
</code></pre>

Unfortunately for me, I was looking for something that could handle dates with "<a href="http://en.wikipedia.org/wiki/Circa" rel="nofollow">circa</a>" (c., ca, ca., circ. or cca.)

<pre><code>&gt;&gt;&gt; ca = parse(u'ca 1900')
&lt;class 'datautil.date.FlexiDate'&gt; [UNPARSED: ca 1900]
</code></pre>

Oh well - I guess I can always send a pull request ;-)

blocks|key|2814502|text|NASA的Spice函数非常好地处理了BC与多种格式的转换。在这些示例中，begin_date和end_date包含与输入日期对应的J2000纪元之后的TDB秒：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2814503|import+spiceypy+as+spice

#+load+a+leap+second+kernel
spicey.furnsh("path/to/leap/second/kernel/naif0012.tls")

begin_date+=+spice.str2et('13201+B.C.+05-06+00:00')
end_date+=+spice.str2et('17191+A.D.+03-15+00:00')++|code-block|syntax|javascript|2814504|Documentation+of+str2et()、Input+format+documentation以及Leapsecond+kernel+files都可以通过美国宇航局的Spice主页获得。|2814505|将datetime或其他时间方法转换为spice非常简单：|2814506|if+indate.year+<+0.0:
++++spice_indate+=+str(indate.year)+%2B+'+B.C.+'+%2B+sindate[-17:]
++++spice_indate+=+str(spice_indate)[1:]
else:+
++++spice_indate+=+str(indate.year)+%2B+'+A.D.+'+%2B+sindate[-17:]

'2018+B.C.+03-31+19:33:38.44'|2814507|其他功能包括:+TIMOUT，TPARSE都可以转换为J2000纪元秒。|2814508|这些函数在python中通过spiceypy提供，例如通过pip3+install+spiceypy安装|2814509|entityMap|0|LINK|mutability|MUTABLE|url|https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/FORTRAN/spicelib/str2et.html|1|https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/FORTRAN/spicelib/tpartv.html|2|https://naif.jpl.nasa.gov/pub/naif/generic_kernels/lsk/|3|https://github.com/AndrewAnnex/SpiceyPy^0|11|A|1C|8|0|0|0|P|0|Q|Q|1|1I|N|2|0|0|0|0|T|L|E|8|3|0^^$0|@$1|2|3|4|5|6|7|18|8|@$9|19|A|1A|B|C]|$9|1B|A|1C|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|1D|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1E|8|@]|D|@$9|1F|A|1G|1|1H]|$9|1I|A|1J|1|1K]|$9|1L|A|1M|1|1N]]|E|$]]|$1|M|3|N|5|6|7|1O|8|@]|D|@]|E|$]]|$1|O|3|P|5|H|7|1P|8|@]|D|@]|E|$I|J]]|$1|Q|3|R|5|6|7|1Q|8|@]|D|@]|E|$]]|$1|S|3|T|5|6|7|1R|8|@$9|1S|A|1T|B|C]]|D|@$9|1U|A|1V|1|1W]]|E|$]]|$1|U|3|-4|5|6|7|1X|8|@]|D|@]|E|$]]]|V|$W|$5|X|Y|Z|E|$10|11]]|12|$5|X|Y|Z|E|$10|13]]|14|$5|X|Y|Z|E|$10|15]]|16|$5|X|Y|Z|E|$10|17]]]]

NASA Spice functions handle BC extremely well with conversions from multiple formats. In these examples <code>begin_date</code> and <code>end_date</code> contain the TDB seconds past the J2000 epoch corresponding to input dates:

<pre class="lang-py prettyprint-override"><code>import spiceypy as spice

# load a leap second kernel
spicey.furnsh("path/to/leap/second/kernel/naif0012.tls")

begin_date = spice.str2et('13201 B.C. 05-06 00:00')
end_date = spice.str2et('17191 A.D. 03-15 00:00') 
</code></pre>

<a href="https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/FORTRAN/spicelib/str2et.html" rel="nofollow noreferrer">Documentation of str2et()</a>,
<a href="https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/FORTRAN/spicelib/tpartv.html" rel="nofollow noreferrer">Input format documentation</a>, as well as
<a href="https://naif.jpl.nasa.gov/pub/naif/generic_kernels/lsk/" rel="nofollow noreferrer">Leapsecond kernel files</a> are available via the NASA Spice homepage.

converting from datetime or other time methods to spice is simple:

<pre><code>if indate.year &lt; 0.0:
 spice_indate = str(indate.year) + ' B.C. ' + sindate[-17:]
 spice_indate = str(spice_indate)[1:]
else: 
 spice_indate = str(indate.year) + ' A.D. ' + sindate[-17:]

'2018 B.C. 03-31 19:33:38.44'
</code></pre>

Other functions include: TIMOUT, TPARSE both converting to and from J2000 epoch seconds.

These functions are available in python through <a href="https://github.com/AndrewAnnex/SpiceyPy" rel="nofollow noreferrer">spiceypy</a>, install e.g. via <code>pip3 install spiceypy</code>

I'm setting out to build an app with Python that will need to handle BC dates extensively (store and retrieve in DB, do calculations). Most dates will be of various uncertainties, like "around 2000BC".

I know Python's datetime library only handles dates from 1 AD.

So far I only found <a href="https://github.com/okfn/datautil/blob/master/datautil/date.py">FlexiDate</a>. Are there any other options?

EDIT: The best approach would probably be to store them as strings (have String as the basic data type) and -as suggested- have a custom datetime class which can make some numerical sense of it. For the majority it looks like dates will only consist of a year. There are some interesting problems to solve like "early 500BC", "between 1600BC and 1500BC", "before 1800BC".

BC dates in Python

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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我正在着手用Python构建一个应用程序，它需要广泛地处理BC日期(在DB中存储和检索，进行计算)。大多数日期都是不确定的，比如“公元前2000年左右”。我知道Python的datetime库只处理公元1年的日期。到目前为止我只找到了。还有没有别的选择？datetime编辑：最好的方法可能是将它们存储为字符串(将字符串...

问Python中的BC日期
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