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<h1>Source code for astropy.coordinates.name_resolve</h1><div class="highlight"><pre>
<span class="c"># Licensed under a 3-clause BSD style license - see LICENSE.rst</span>
<span class="sd">"""</span>
<span class="sd">This module contains convenience functions for getting a coordinate object</span>
<span class="sd">for a named object by querying SESAME and getting the first returned result.</span>
<span class="sd">Note that this is intended to be a convenience, and is very simple. If you</span>
<span class="sd">need precise coordinates for an object you should find the appropriate</span>
<span class="sd">reference for that measurement and input the coordinates manually.</span>
<span class="sd">"""</span>
<span class="kn">from</span> <span class="nn">__future__</span> <span class="kn">import</span> <span class="n">division</span><span class="p">,</span> <span class="n">print_function</span>
<span class="c"># Standard library</span>
<span class="kn">import</span> <span class="nn">os</span>
<span class="kn">import</span> <span class="nn">re</span>
<span class="kn">import</span> <span class="nn">sys</span>
<span class="kn">import</span> <span class="nn">httplib</span>
<span class="kn">import</span> <span class="nn">urllib</span>
<span class="kn">import</span> <span class="nn">urllib2</span>
<span class="kn">from</span> <span class="nn">urlparse</span> <span class="kn">import</span> <span class="n">urlparse</span>
<span class="kn">import</span> <span class="nn">socket</span>
<span class="c"># Third party</span>
<span class="kn">import</span> <span class="nn">numpy</span> <span class="kn">as</span> <span class="nn">np</span>
<span class="c"># Astropy</span>
<span class="kn">from</span> <span class="nn">..config</span> <span class="kn">import</span> <span class="n">ConfigurationItem</span>
<span class="kn">from</span> <span class="nn">.builtin_systems</span> <span class="kn">import</span> <span class="n">ICRSCoordinates</span>
<span class="kn">from</span> <span class="nn">..</span> <span class="kn">import</span> <span class="n">units</span> <span class="k">as</span> <span class="n">u</span>
<span class="n">__all__</span> <span class="o">=</span> <span class="p">[</span><span class="s">"get_icrs_coordinates"</span><span class="p">]</span>
<span class="n">SESAME_URL</span> <span class="o">=</span> <span class="n">ConfigurationItem</span><span class="p">(</span><span class="s">"sesame_url"</span><span class="p">,</span>
<span class="p">[</span><span class="s">"http://cdsweb.u-strasbg.fr/cgi-bin/nph-sesame/"</span><span class="p">,</span>
<span class="s">"http://vizier.cfa.harvard.edu/viz-bin/nph-sesame/"</span><span class="p">],</span>
<span class="s">"The URL to Sesame's web-queryable database."</span><span class="p">,</span>
<span class="n">cfgtype</span><span class="o">=</span><span class="s">'string_list'</span><span class="p">)</span>
<span class="n">SESAME_DATABASE</span> <span class="o">=</span> <span class="n">ConfigurationItem</span><span class="p">(</span><span class="s">"sesame_database"</span><span class="p">,</span> <span class="p">[</span><span class="s">'all'</span><span class="p">,</span> <span class="s">'simbad'</span><span class="p">,</span> <span class="s">'ned'</span><span class="p">,</span>
<span class="s">'vizier'</span><span class="p">],</span>
<span class="s">"This specifies the default database that "</span>
<span class="s">"SESAME will query when using the name "</span>
<span class="s">"resolve mechanism in the coordinates "</span>
<span class="s">"subpackage. Default is to search all "</span>
<span class="s">"databases, but this can be 'all', "</span>
<span class="s">"'simbad', 'ned', or 'vizier'."</span><span class="p">)</span>
<span class="n">NAME_RESOLVE_TIMEOUT</span> <span class="o">=</span> <span class="n">ConfigurationItem</span><span class="p">(</span><span class="s">'name_resolve_timeout'</span><span class="p">,</span> <span class="mi">5</span><span class="p">,</span>
<span class="s">"This is the maximum time to wait "</span>
<span class="s">"for a response from a name resolve "</span>
<span class="s">"query to SESAME in seconds."</span><span class="p">)</span>
<span class="k">class</span> <span class="nc">NameResolveError</span><span class="p">(</span><span class="ne">Exception</span><span class="p">):</span>
<span class="k">pass</span>
<span class="k">def</span> <span class="nf">_parse_response</span><span class="p">(</span><span class="n">resp_data</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Given a string response from SESAME, parse out the coordinates by looking</span>
<span class="sd"> for a line starting with a J, meaning ICRS J2000 coordinates.</span>
<span class="sd"> </span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> resp_data : str</span>
<span class="sd"> The string HTTP response from SESAME.</span>
<span class="sd"> </span>
<span class="sd"> Returns</span>
<span class="sd"> -------</span>
<span class="sd"> ra : str</span>
<span class="sd"> The string Right Ascension parsed from the HTTP response.</span>
<span class="sd"> dec : str</span>
<span class="sd"> The string Declination parsed from the HTTP response.</span>
<span class="sd"> """</span>
<span class="n">pattr</span> <span class="o">=</span> <span class="n">re</span><span class="o">.</span><span class="n">compile</span><span class="p">(</span><span class="s">r"%J\s*([0-9\.]+)\s*([\+\-\.0-9]+)"</span><span class="p">)</span>
<span class="n">matched</span> <span class="o">=</span> <span class="n">pattr</span><span class="o">.</span><span class="n">search</span><span class="p">(</span><span class="n">resp_data</span><span class="o">.</span><span class="n">decode</span><span class="p">(</span><span class="s">'utf-8'</span><span class="p">))</span>
<span class="k">if</span> <span class="n">matched</span> <span class="o">==</span> <span class="bp">None</span><span class="p">:</span>
<span class="k">return</span> <span class="bp">None</span><span class="p">,</span> <span class="bp">None</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">ra</span><span class="p">,</span><span class="n">dec</span> <span class="o">=</span> <span class="n">matched</span><span class="o">.</span><span class="n">groups</span><span class="p">()</span>
<span class="k">return</span> <span class="n">ra</span><span class="p">,</span><span class="n">dec</span>
<div class="viewcode-block" id="get_icrs_coordinates"><a class="viewcode-back" href="../../../_generated/astropy.coordinates.name_resolve.get_icrs_coordinates.html#astropy.coordinates.name_resolve.get_icrs_coordinates">[docs]</a><span class="k">def</span> <span class="nf">get_icrs_coordinates</span><span class="p">(</span><span class="n">name</span><span class="p">):</span>
<span class="sd">""" </span>
<span class="sd"> Retrieve an ICRSCoordinates object by using an online name resolving</span>
<span class="sd"> service to retrieve coordinates for the specified name. By default,</span>
<span class="sd"> this will search all available databases until a match is found. If</span>
<span class="sd"> you would like to specify the database, use the configuration item</span>
<span class="sd"> `name_resolve.SESAME_DATABASE` . You can also specify a list of servers </span>
<span class="sd"> to use for querying Sesame using the configuration item </span>
<span class="sd"> `name_resolve.SESAME_URL`. This will try each one in order until a valid</span>
<span class="sd"> response is returned. By default, this list includes the main Sesame </span>
<span class="sd"> host and a mirror at vizier. A final configuration item, </span>
<span class="sd"> `name_resolve.NAME_RESOLVE_TIMEOUT`, is the number of seconds to wait</span>
<span class="sd"> for a response from the server before giving up. By default this is </span>
<span class="sd"> 5 seconds.</span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> name : str</span>
<span class="sd"> The name of the object to get coordinates for, e.g. M42.</span>
<span class="sd"> Returns</span>
<span class="sd"> -------</span>
<span class="sd"> coord : SphericalCoordinatesBase</span>
<span class="sd"> An `ICRSCoordinates` instance for the object name specified.</span>
<span class="sd"> </span>
<span class="sd"> """</span>
<span class="n">database</span> <span class="o">=</span> <span class="n">SESAME_DATABASE</span><span class="p">()</span>
<span class="c"># The web API just takes the first letter of the database name</span>
<span class="n">db</span> <span class="o">=</span> <span class="n">database</span><span class="o">.</span><span class="n">upper</span><span class="p">()[</span><span class="mi">0</span><span class="p">]</span>
<span class="c"># Make sure we don't have duplicates in the url list</span>
<span class="n">urls</span> <span class="o">=</span> <span class="p">[]</span>
<span class="n">domains</span> <span class="o">=</span> <span class="p">[]</span>
<span class="k">for</span> <span class="n">url</span> <span class="ow">in</span> <span class="n">SESAME_URL</span><span class="p">():</span>
<span class="n">domain</span> <span class="o">=</span> <span class="n">urlparse</span><span class="p">(</span><span class="n">url</span><span class="p">)</span><span class="o">.</span><span class="n">netloc</span>
<span class="c"># Check for duplicates</span>
<span class="k">if</span> <span class="n">domain</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">domains</span><span class="p">:</span>
<span class="n">domains</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">domain</span><span class="p">)</span>
<span class="c"># Add the query to the end of the url, add to url list</span>
<span class="n">fmt_url</span> <span class="o">=</span> <span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">url</span><span class="p">,</span> <span class="s">"{db}?{name}"</span><span class="p">)</span>
<span class="n">fmt_url</span> <span class="o">=</span> <span class="n">fmt_url</span><span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">name</span><span class="o">=</span><span class="n">urllib</span><span class="o">.</span><span class="n">quote</span><span class="p">(</span><span class="n">name</span><span class="p">),</span> <span class="n">db</span><span class="o">=</span><span class="n">db</span><span class="p">)</span>
<span class="n">urls</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">fmt_url</span><span class="p">)</span>
<span class="k">for</span> <span class="n">url</span> <span class="ow">in</span> <span class="n">urls</span><span class="p">:</span>
<span class="k">try</span><span class="p">:</span>
<span class="c"># Retrieve ascii name resolve data from CDS</span>
<span class="n">resp</span> <span class="o">=</span> <span class="n">urllib2</span><span class="o">.</span><span class="n">urlopen</span><span class="p">(</span><span class="n">url</span><span class="p">,</span> <span class="n">timeout</span><span class="o">=</span><span class="n">NAME_RESOLVE_TIMEOUT</span><span class="p">())</span>
<span class="k">break</span>
<span class="k">except</span> <span class="n">urllib2</span><span class="o">.</span><span class="n">URLError</span><span class="p">,</span> <span class="n">e</span><span class="p">:</span>
<span class="c"># This catches a timeout error, see:</span>
<span class="c"># http://stackoverflow.com/questions/2712524/handling-urllib2s-timeout-python</span>
<span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">e</span><span class="o">.</span><span class="n">reason</span><span class="p">,</span> <span class="n">socket</span><span class="o">.</span><span class="n">timeout</span><span class="p">):</span>
<span class="c"># If it was a timeout, try with the next URL</span>
<span class="k">continue</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">raise</span> <span class="n">NameResolveError</span><span class="p">(</span><span class="s">"Unable to retrieve coordinates for name "</span>
<span class="s">"'{0}'"</span><span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">name</span><span class="p">))</span>
<span class="c"># All Sesame URL's timed out...</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">raise</span> <span class="n">NameResolveError</span><span class="p">(</span><span class="s">"All Sesame queries timed out. Unable to "</span>
<span class="s">"retrieve coordinates."</span><span class="p">)</span>
<span class="n">resp_data</span> <span class="o">=</span> <span class="n">resp</span><span class="o">.</span><span class="n">read</span><span class="p">()</span>
<span class="n">ra</span><span class="p">,</span><span class="n">dec</span> <span class="o">=</span> <span class="n">_parse_response</span><span class="p">(</span><span class="n">resp_data</span><span class="p">)</span>
<span class="k">if</span> <span class="n">ra</span> <span class="o">==</span> <span class="bp">None</span> <span class="ow">and</span> <span class="n">dec</span> <span class="o">==</span> <span class="bp">None</span><span class="p">:</span>
<span class="k">if</span> <span class="n">db</span> <span class="o">==</span> <span class="s">"A"</span><span class="p">:</span>
<span class="n">err</span> <span class="o">=</span> <span class="s">"Unable to find coordinates for name '{0}'"</span><span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">name</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">err</span> <span class="o">=</span> <span class="s">"Unable to find coordinates for name '{0}' in database {1}"</span>\
<span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="n">database</span><span class="p">)</span>
<span class="k">raise</span> <span class="n">NameResolveError</span><span class="p">(</span><span class="n">err</span><span class="p">)</span>
<span class="k">return</span> <span class="n">ICRSCoordinates</span><span class="p">(</span><span class="n">ra</span><span class="p">,</span> <span class="n">dec</span><span class="p">,</span> <span class="n">unit</span><span class="o">=</span><span class="p">(</span><span class="n">u</span><span class="o">.</span><span class="n">degree</span><span class="p">,</span> <span class="n">u</span><span class="o">.</span><span class="n">degree</span><span class="p">))</span></div>
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