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//usr/share/doc/python-babel-0.9.4/doc/dates.html
<!DOCTYPE html> <html lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <meta name="generator" content="Docutils 0.4: http://docutils.sourceforge.net/"> <title>Date Formatting</title> <link rel="stylesheet" href="common/style/edgewall.css" type="text/css"> </head> <body> <div class="document" id="date-formatting"> <div id="navigation"> <span class="projinfo">Babel 0.9.4</span> <a href="index.html">Documentation Index</a> </div> <h1 class="title">Date Formatting</h1> <div class="contents topic"> <p class="topic-title first"><a id="contents" name="contents">Contents</a></p> <ul class="auto-toc simple"> <li><a class="reference" href="#pattern-syntax" id="id1" name="id1">1 Pattern Syntax</a><ul class="auto-toc"> <li><a class="reference" href="#date-fields" id="id2" name="id2">1.1 Date Fields</a></li> <li><a class="reference" href="#time-fields" id="id3" name="id3">1.2 Time Fields</a></li> </ul> </li> <li><a class="reference" href="#time-zone-support" id="id4" name="id4">2 Time-zone Support</a><ul class="auto-toc"> <li><a class="reference" href="#localized-time-zone-names" id="id5" name="id5">2.1 Localized Time-zone Names</a></li> </ul> </li> <li><a class="reference" href="#parsing-dates" id="id6" name="id6">3 Parsing Dates</a></li> </ul> </div> <p>When working with date and time information in Python, you commonly use the classes <tt class="docutils literal"><span class="pre">date</span></tt>, <tt class="docutils literal"><span class="pre">datetime</span></tt> and/or <tt class="docutils literal"><span class="pre">time</span></tt> from the <a class="reference" href="http://docs.python.org/lib/module-datetime.html">datetime</a> package. Babel provides functions for locale-specific formatting of those objects in its <tt class="docutils literal"><span class="pre">dates</span></tt> module:</p> <div class="highlight"><pre><span class="gp">>>> </span><span class="k">from</span> <span class="nn">datetime</span> <span class="k">import</span> <span class="n">date</span><span class="p">,</span> <span class="n">datetime</span><span class="p">,</span> <span class="n">time</span> <span class="gp">>>> </span><span class="k">from</span> <span class="nn">babel.dates</span> <span class="k">import</span> <span class="n">format_date</span><span class="p">,</span> <span class="n">format_datetime</span><span class="p">,</span> <span class="n">format_time</span> <span class="gp">>>> </span><span class="n">d</span> <span class="o">=</span> <span class="n">date</span><span class="p">(</span><span class="mf">2007</span><span class="p">,</span> <span class="mf">4</span><span class="p">,</span> <span class="mf">1</span><span class="p">)</span> <span class="gp">>>> </span><span class="n">format_date</span><span class="p">(</span><span class="n">d</span><span class="p">,</span> <span class="n">locale</span><span class="o">=</span><span class="s">'en'</span><span class="p">)</span> <span class="go">u'Apr 1, 2007'</span> <span class="gp">>>> </span><span class="n">format_date</span><span class="p">(</span><span class="n">d</span><span class="p">,</span> <span class="n">locale</span><span class="o">=</span><span class="s">'de_DE'</span><span class="p">)</span> <span class="go">u'01.04.2007'</span> </pre></div> <p>As this example demonstrates, Babel will automatically choose a date format that is appropriate for the requested locale.</p> <p>The <tt class="docutils literal"><span class="pre">format_*()</span></tt> functions also accept an optional <tt class="docutils literal"><span class="pre">format</span></tt> argument, which allows you to choose between one of four format variations:</p> <blockquote> <ul class="simple"> <li><tt class="docutils literal"><span class="pre">short</span></tt>,</li> <li><tt class="docutils literal"><span class="pre">medium</span></tt> (the default),</li> <li><tt class="docutils literal"><span class="pre">long</span></tt>, and</li> <li><tt class="docutils literal"><span class="pre">full</span></tt>.</li> </ul> </blockquote> <p>For example:</p> <div class="highlight"><pre><span class="gp">>>> </span><span class="n">format_date</span><span class="p">(</span><span class="n">d</span><span class="p">,</span> <span class="n">format</span><span class="o">=</span><span class="s">'short'</span><span class="p">,</span> <span class="n">locale</span><span class="o">=</span><span class="s">'en'</span><span class="p">)</span> <span class="go">u'4/1/07'</span> <span class="gp">>>> </span><span class="n">format_date</span><span class="p">(</span><span class="n">d</span><span class="p">,</span> <span class="n">format</span><span class="o">=</span><span class="s">'long'</span><span class="p">,</span> <span class="n">locale</span><span class="o">=</span><span class="s">'en'</span><span class="p">)</span> <span class="go">u'April 1, 2007'</span> <span class="gp">>>> </span><span class="n">format_date</span><span class="p">(</span><span class="n">d</span><span class="p">,</span> <span class="n">format</span><span class="o">=</span><span class="s">'full'</span><span class="p">,</span> <span class="n">locale</span><span class="o">=</span><span class="s">'en'</span><span class="p">)</span> <span class="go">u'Sunday, April 1, 2007'</span> </pre></div> <div class="section"> <h1><a id="pattern-syntax" name="pattern-syntax">1 Pattern Syntax</a></h1> <p>While Babel makes it simple to use the appropriate date/time format for a given locale, you can also force it to use custom patterns. Note that Babel uses different patterns for specifying number and date formats compared to the Python equivalents (such as <tt class="docutils literal"><span class="pre">time.strftime()</span></tt>), which have mostly been inherited from C and POSIX. The patterns used in Babel are based on the <a class="reference" href="http://unicode.org/reports/tr35/#Date_Format_Patterns">Locale Data Markup Language specification</a> (LDML), which defines them as follows:</p> <blockquote> <p>A date/time pattern is a string of characters, where specific strings of characters are replaced with date and time data from a calendar when formatting or used to generate data for a calendar when parsing. […]</p> <p>Characters may be used multiple times. For example, if <tt class="docutils literal"><span class="pre">y</span></tt> is used for the year, <tt class="docutils literal"><span class="pre">yy</span></tt> might produce "99", whereas <tt class="docutils literal"><span class="pre">yyyy</span></tt> produces "1999". For most numerical fields, the number of characters specifies the field width. For example, if <tt class="docutils literal"><span class="pre">h</span></tt> is the hour, <tt class="docutils literal"><span class="pre">h</span></tt> might produce "5", but <tt class="docutils literal"><span class="pre">hh</span></tt> produces "05". For some characters, the count specifies whether an abbreviated or full form should be used […]</p> <p>Two single quotes represent a literal single quote, either inside or outside single quotes. Text within single quotes is not interpreted in any way (except for two adjacent single quotes).</p> </blockquote> <p>For example:</p> <div class="highlight"><pre><span class="gp">>>> </span><span class="n">d</span> <span class="o">=</span> <span class="n">date</span><span class="p">(</span><span class="mf">2007</span><span class="p">,</span> <span class="mf">4</span><span class="p">,</span> <span class="mf">1</span><span class="p">)</span> <span class="gp">>>> </span><span class="n">format_date</span><span class="p">(</span><span class="n">d</span><span class="p">,</span> <span class="s">"EEE, MMM d, ''yy"</span><span class="p">,</span> <span class="n">locale</span><span class="o">=</span><span class="s">'en'</span><span class="p">)</span> <span class="go">u"Sun, Apr 1, '07"</span> <span class="gp">>>> </span><span class="n">format_date</span><span class="p">(</span><span class="n">d</span><span class="p">,</span> <span class="s">"EEEE, d.M.yyyy"</span><span class="p">,</span> <span class="n">locale</span><span class="o">=</span><span class="s">'de'</span><span class="p">)</span> <span class="go">u'Sonntag, 1.4.2007'</span> <span class="gp">>>> </span><span class="n">t</span> <span class="o">=</span> <span class="n">time</span><span class="p">(</span><span class="mf">15</span><span class="p">,</span> <span class="mf">30</span><span class="p">)</span> <span class="gp">>>> </span><span class="n">format_time</span><span class="p">(</span><span class="n">t</span><span class="p">,</span> <span class="s">"hh 'o''clock' a"</span><span class="p">,</span> <span class="n">locale</span><span class="o">=</span><span class="s">'en'</span><span class="p">)</span> <span class="go">u"03 o'clock PM"</span> <span class="gp">>>> </span><span class="n">format_time</span><span class="p">(</span><span class="n">t</span><span class="p">,</span> <span class="s">'H:mm a'</span><span class="p">,</span> <span class="n">locale</span><span class="o">=</span><span class="s">'de'</span><span class="p">)</span> <span class="go">u'15:30 nachm.'</span> <span class="gp">>>> </span><span class="n">dt</span> <span class="o">=</span> <span class="n">datetime</span><span class="p">(</span><span class="mf">2007</span><span class="p">,</span> <span class="mf">4</span><span class="p">,</span> <span class="mf">1</span><span class="p">,</span> <span class="mf">15</span><span class="p">,</span> <span class="mf">30</span><span class="p">)</span> <span class="gp">>>> </span><span class="n">format_datetime</span><span class="p">(</span><span class="n">dt</span><span class="p">,</span> <span class="s">"yyyyy.MMMM.dd GGG hh:mm a"</span><span class="p">,</span> <span class="n">locale</span><span class="o">=</span><span class="s">'en'</span><span class="p">)</span> <span class="go">u'02007.April.01 AD 03:30 PM'</span> </pre></div> <p>The syntax for custom datetime format patterns is described in detail in the the <a class="reference" href="http://unicode.org/reports/tr35/#Date_Format_Patterns">Locale Data Markup Language specification</a>. The following table is just a relatively brief overview.</p> <blockquote> </blockquote> <div class="section"> <h2><a id="date-fields" name="date-fields">1.1 Date Fields</a></h2> <blockquote> <table border="1" class="docutils"> <colgroup> <col width="14%"> <col width="11%"> <col width="76%"> </colgroup> <thead valign="bottom"> <tr><th class="head">Field</th> <th class="head">Symbol</th> <th class="head">Description</th> </tr> </thead> <tbody valign="top"> <tr><td>Era</td> <td><tt class="docutils literal"><span class="pre">G</span></tt></td> <td>Replaced with the era string for the current date. One to three letters for the abbreviated form, four lettersfor the long form, five for the narrow form</td> </tr> <tr><td rowspan="3">Year</td> <td><tt class="docutils literal"><span class="pre">y</span></tt></td> <td>Replaced by the year. Normally the length specifies the padding, but for two letters it also specifies the maximum length.</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">Y</span></tt></td> <td>Same as <tt class="docutils literal"><span class="pre">y</span></tt> but uses the ISO year-week calendar.</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">u</span></tt></td> <td>??</td> </tr> <tr><td rowspan="2">Quarter</td> <td><tt class="docutils literal"><span class="pre">Q</span></tt></td> <td>Use one or two for the numerical quarter, three for the abbreviation, or four for the full name.</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">q</span></tt></td> <td>Use one or two for the numerical quarter, three for the abbreviation, or four for the full name.</td> </tr> <tr><td rowspan="2">Month</td> <td><tt class="docutils literal"><span class="pre">M</span></tt></td> <td>Use one or two for the numerical month, three for the abbreviation, or four for the full name, or five for the narrow name.</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">L</span></tt></td> <td>Use one or two for the numerical month, three for the abbreviation, or four for the full name, or 5 for the narrow name.</td> </tr> <tr><td rowspan="2">Week</td> <td><tt class="docutils literal"><span class="pre">w</span></tt></td> <td>Week of year.</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">W</span></tt></td> <td>Week of month.</td> </tr> <tr><td rowspan="4">Day</td> <td><tt class="docutils literal"><span class="pre">d</span></tt></td> <td>Day of month.</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">D</span></tt></td> <td>Day of year.</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">F</span></tt></td> <td>Day of week in month.</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">g</span></tt></td> <td>??</td> </tr> <tr><td rowspan="3">Week day</td> <td><tt class="docutils literal"><span class="pre">E</span></tt></td> <td>Day of week. Use one through three letters for the short day, or four for the full name, or five for the narrow name.</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">e</span></tt></td> <td>Local day of week. Same as E except adds a numeric value that will depend on the local starting day of the week, using one or two letters.</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">c</span></tt></td> <td>??</td> </tr> </tbody> </table> </blockquote> </div> <div class="section"> <h2><a id="time-fields" name="time-fields">1.2 Time Fields</a></h2> <blockquote> <table border="1" class="docutils"> <colgroup> <col width="14%"> <col width="11%"> <col width="76%"> </colgroup> <thead valign="bottom"> <tr><th class="head">Field</th> <th class="head">Symbol</th> <th class="head">Description</th> </tr> </thead> <tbody valign="top"> <tr><td>Period</td> <td><tt class="docutils literal"><span class="pre">a</span></tt></td> <td>AM or PM</td> </tr> <tr><td rowspan="4">Hour</td> <td><tt class="docutils literal"><span class="pre">h</span></tt></td> <td>Hour [1-12].</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">H</span></tt></td> <td>Hour [0-23].</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">K</span></tt></td> <td>Hour [0-11].</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">k</span></tt></td> <td>Hour [1-24].</td> </tr> <tr><td>Minute</td> <td><tt class="docutils literal"><span class="pre">m</span></tt></td> <td>Use one or two for zero places padding.</td> </tr> <tr><td rowspan="3">Second</td> <td><tt class="docutils literal"><span class="pre">s</span></tt></td> <td>Use one or two for zero places padding.</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">S</span></tt></td> <td>Fractional second, rounds to the count of letters.</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">A</span></tt></td> <td>Milliseconds in day.</td> </tr> <tr><td rowspan="4">Timezone</td> <td><tt class="docutils literal"><span class="pre">z</span></tt></td> <td>Use one to three letters for the short timezone or four for the full name.</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">Z</span></tt></td> <td>Use one to three letters for RFC 822, four letters for GMT format.</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">v</span></tt></td> <td>Use one letter for short wall (generic) time, four for long wall time.</td> </tr> <tr><td><tt class="docutils literal"><span class="pre">V</span></tt></td> <td>Same as <tt class="docutils literal"><span class="pre">z</span></tt>, except that timezone abbreviations should be used regardless of whether they are in common use by the locale.</td> </tr> </tbody> </table> </blockquote> </div> </div> <div class="section"> <h1><a id="time-zone-support" name="time-zone-support">2 Time-zone Support</a></h1> <p>Many of the verbose time formats include the time-zone, but time-zone information is not by default available for the Python <tt class="docutils literal"><span class="pre">datetime</span></tt> and <tt class="docutils literal"><span class="pre">time</span></tt> objects. The standard library includes only the abstract <tt class="docutils literal"><span class="pre">tzinfo</span></tt> class, which you need appropriate implementations for to actually use in your application. Babel includes a <tt class="docutils literal"><span class="pre">tzinfo</span></tt> implementation for UTC (Universal Time).</p> <p>For real time-zone support, it is strongly recommended that you use the third-party package <a class="reference" href="http://pytz.sourceforge.net/">pytz</a>, which includes the definitions of practically all of the time-zones used on the world, as well as important functions for reliably converting from UTC to local time, and vice versa:</p> <div class="highlight"><pre><span class="gp">>>> </span><span class="k">from</span> <span class="nn">datetime</span> <span class="k">import</span> <span class="n">time</span> <span class="gp">>>> </span><span class="k">from</span> <span class="nn">pytz</span> <span class="k">import</span> <span class="n">timezone</span><span class="p">,</span> <span class="n">utc</span> <span class="gp">>>> </span><span class="n">dt</span> <span class="o">=</span> <span class="n">datetime</span><span class="p">(</span><span class="mf">2007</span><span class="p">,</span> <span class="mf">04</span><span class="p">,</span> <span class="mf">01</span><span class="p">,</span> <span class="mf">15</span><span class="p">,</span> <span class="mf">30</span><span class="p">,</span> <span class="n">tzinfo</span><span class="o">=</span><span class="n">utc</span><span class="p">)</span> <span class="gp">>>> </span><span class="n">eastern</span> <span class="o">=</span> <span class="n">timezone</span><span class="p">(</span><span class="s">'US/Eastern'</span><span class="p">)</span> <span class="gp">>>> </span><span class="n">format_datetime</span><span class="p">(</span><span class="n">dt</span><span class="p">,</span> <span class="s">'H:mm Z'</span><span class="p">,</span> <span class="n">tzinfo</span><span class="o">=</span><span class="n">eastern</span><span class="p">,</span> <span class="n">locale</span><span class="o">=</span><span class="s">'en_US'</span><span class="p">)</span> <span class="go">u'11:30 -0400'</span> </pre></div> <p>The recommended approach to deal with different time-zones in a Python application is to always use UTC internally, and only convert from/to the users time-zone when accepting user input and displaying date/time data, respectively. You can use Babel together with <tt class="docutils literal"><span class="pre">pytz</span></tt> to apply a time-zone to any <tt class="docutils literal"><span class="pre">datetime</span></tt> or <tt class="docutils literal"><span class="pre">time</span></tt> object for display, leaving the original information unchanged:</p> <div class="highlight"><pre><span class="gp">>>> </span><span class="n">british</span> <span class="o">=</span> <span class="n">timezone</span><span class="p">(</span><span class="s">'Europe/London'</span><span class="p">)</span> <span class="gp">>>> </span><span class="n">format_datetime</span><span class="p">(</span><span class="n">dt</span><span class="p">,</span> <span class="s">'H:mm zzzz'</span><span class="p">,</span> <span class="n">tzinfo</span><span class="o">=</span><span class="n">british</span><span class="p">,</span> <span class="n">locale</span><span class="o">=</span><span class="s">'en_US'</span><span class="p">)</span> <span class="go">u'16:30 British Summer Time'</span> </pre></div> <p>Here, the given UTC time is adjusted to the "Europe/London" time-zone, and daylight savings time is taken into account. Daylight savings time is also applied to <tt class="docutils literal"><span class="pre">format_time</span></tt>, but because the actual date is unknown in that case, the current day is assumed to determine whether DST or standard time should be used.</p> <blockquote> </blockquote> <div class="section"> <h2><a id="localized-time-zone-names" name="localized-time-zone-names">2.1 Localized Time-zone Names</a></h2> <p>While the <tt class="docutils literal"><span class="pre">Locale</span></tt> class provides access to various locale display names related to time-zones, the process of building a localized name of a time-zone is actually quite complicated. Babel implements it in separately usable functions in the <tt class="docutils literal"><span class="pre">babel.dates</span></tt> module, most importantly the <tt class="docutils literal"><span class="pre">get_timezone_name</span></tt> function:</p> <div class="highlight"><pre><span class="gp">>>> </span><span class="k">from</span> <span class="nn">pytz</span> <span class="k">import</span> <span class="n">timezone</span> <span class="gp">>>> </span><span class="k">from</span> <span class="nn">babel</span> <span class="k">import</span> <span class="n">Locale</span> <span class="gp">>>> </span><span class="k">from</span> <span class="nn">babel.dates</span> <span class="k">import</span> <span class="n">get_timezone_name</span> <span class="gp">>>> </span><span class="n">tz</span> <span class="o">=</span> <span class="n">timezone</span><span class="p">(</span><span class="s">'Europe/Berlin'</span><span class="p">)</span> <span class="gp">>>> </span><span class="n">get_timezone_name</span><span class="p">(</span><span class="n">tz</span><span class="p">,</span> <span class="n">locale</span><span class="o">=</span><span class="n">Locale</span><span class="o">.</span><span class="n">parse</span><span class="p">(</span><span class="s">'pt_PT'</span><span class="p">))</span> <span class="go">u'Hor\xe1rio Alemanha'</span> </pre></div> <p>You can pass the function either a <tt class="docutils literal"><span class="pre">datetime.tzinfo</span></tt> object, or a <tt class="docutils literal"><span class="pre">datetime.date</span></tt> or <tt class="docutils literal"><span class="pre">datetime.datetime</span></tt> object. If you pass an actual date, the function will be able to take daylight savings time into account. If you pass just the time-zone, Babel does not know whether daylight savings time is in effect, so it uses a generic representation, which is useful for example to display a list of time-zones to the user.</p> <div class="highlight"><pre><span class="gp">>>> </span><span class="k">from</span> <span class="nn">datetime</span> <span class="k">import</span> <span class="n">datetime</span> <span class="gp">>>> </span><span class="n">dt</span> <span class="o">=</span> <span class="n">tz</span><span class="o">.</span><span class="n">localize</span><span class="p">(</span><span class="n">datetime</span><span class="p">(</span><span class="mf">2007</span><span class="p">,</span> <span class="mf">8</span><span class="p">,</span> <span class="mf">15</span><span class="p">))</span> <span class="gp">>>> </span><span class="n">get_timezone_name</span><span class="p">(</span><span class="n">dt</span><span class="p">,</span> <span class="n">locale</span><span class="o">=</span><span class="n">Locale</span><span class="o">.</span><span class="n">parse</span><span class="p">(</span><span class="s">'de_DE'</span><span class="p">))</span> <span class="go">u'Mitteleurop\xe4ische Sommerzeit'</span> <span class="gp">>>> </span><span class="n">get_timezone_name</span><span class="p">(</span><span class="n">tz</span><span class="p">,</span> <span class="n">locale</span><span class="o">=</span><span class="n">Locale</span><span class="o">.</span><span class="n">parse</span><span class="p">(</span><span class="s">'de_DE'</span><span class="p">))</span> <span class="go">u'Deutschland'</span> </pre></div> </div> </div> <div class="section"> <h1><a id="parsing-dates" name="parsing-dates">3 Parsing Dates</a></h1> <p>Babel can also parse date and time information in a locale-sensitive manner:</p> <div class="highlight"><pre><span class="gp">>>> </span><span class="k">from</span> <span class="nn">babel.dates</span> <span class="k">import</span> <span class="n">parse_date</span><span class="p">,</span> <span class="n">parse_datetime</span><span class="p">,</span> <span class="n">parse_time</span> </pre></div> <div class="note"> <p class="first admonition-title">Note</p> <p class="last">Date/time parsing is not properly implemented yet</p> </div> </div> <div id="footer"> Visit the Babel open source project at <a href="http://babel.edgewall.org/">http://babel.edgewall.org/</a> </div> </div> </body> </html>
