Baoding-FenShuaJiang
/
Green_GoodERP18_FSJ_Standard
Observar 1
Favorito 0
Wiki 捐赠
gooderp18绿色标准版
Você não pode selecionar mais de 25 tópicos Os tópicos devem começar com uma letra ou um número, podem incluir traços ('-') e podem ter até 35 caracteres.
Tag: 0f75e31513
Branches Tags
${ item.name }
Criar branch ${ searchTerm }
de 0f75e31513
${ noResults }
Green_GoodERP18_FSJ_Standard/python/Doc/html/library/graphlib.html

527 linhas
37KB
Original Anotar Histórico 

  1. <!DOCTYPE html>

  2. 

  3. <html lang="en" data-content_root="../">

  4.   <head>

  5.     <meta charset="utf-8" />

  6.     <meta name="viewport" content="width=device-width, initial-scale=1.0" /><meta name="viewport" content="width=device-width, initial-scale=1" />

  7. <meta property="og:title" content="graphlib — Functionality to operate with graph-like structures" />

  8. <meta property="og:type" content="website" />

  9. <meta property="og:url" content="https://docs.python.org/3/library/graphlib.html" />

  10. <meta property="og:site_name" content="Python documentation" />

  11. <meta property="og:description" content="Source code: Lib/graphlib.py Exceptions: The graphlib module defines the following exception classes:" />

  12. <meta property="og:image" content="https://docs.python.org/3/_static/og-image.png" />

  13. <meta property="og:image:alt" content="Python documentation" />

  14. <meta name="description" content="Source code: Lib/graphlib.py Exceptions: The graphlib module defines the following exception classes:" />

  15. <meta property="og:image:width" content="200" />

  16. <meta property="og:image:height" content="200" />

  17. <meta name="theme-color" content="#3776ab" />

  18. 

  19.     <title>graphlib — Functionality to operate with graph-like structures &#8212; Python 3.12.3 documentation</title><meta name="viewport" content="width=device-width, initial-scale=1.0">

  20.     

  21.     <link rel="stylesheet" type="text/css" href="../_static/pygments.css?v=80d5e7a1" />

  22.     <link rel="stylesheet" type="text/css" href="../_static/pydoctheme.css?v=bb723527" />

  23.     <link id="pygments_dark_css" media="(prefers-color-scheme: dark)" rel="stylesheet" type="text/css" href="../_static/pygments_dark.css?v=b20cc3f5" />

  24.     

  25.     <script src="../_static/documentation_options.js?v=2c828074"></script>

  26.     <script src="../_static/doctools.js?v=888ff710"></script>

  27.     <script src="../_static/sphinx_highlight.js?v=dc90522c"></script>

  28.     

  29.     <script src="../_static/sidebar.js"></script>

  30.     

  31.     <link rel="search" type="application/opensearchdescription+xml"

  32.           title="Search within Python 3.12.3 documentation"

  33.           href="../_static/opensearch.xml"/>

  34.     <link rel="author" title="About these documents" href="../about.html" />

  35.     <link rel="index" title="Index" href="../genindex.html" />

  36.     <link rel="search" title="Search" href="../search.html" />

  37.     <link rel="copyright" title="Copyright" href="../copyright.html" />

  38.     <link rel="next" title="Numeric and Mathematical Modules" href="numeric.html" />

  39.     <link rel="prev" title="enum — Support for enumerations" href="enum.html" />

  40.     <link rel="canonical" href="https://docs.python.org/3/library/graphlib.html" />

  41.     

  42.       

  43.     

  44. 

  45.     

  46.     <style>

  47.       @media only screen {

  48.         table.full-width-table {

  49.             width: 100%;

  50.         }

  51.       }

  52.     </style>

  53. <link rel="stylesheet" href="../_static/pydoctheme_dark.css" media="(prefers-color-scheme: dark)" id="pydoctheme_dark_css">

  54.     <link rel="shortcut icon" type="image/png" href="../_static/py.svg" />

  55.             <script type="text/javascript" src="../_static/copybutton.js"></script>

  56.             <script type="text/javascript" src="../_static/menu.js"></script>

  57.             <script type="text/javascript" src="../_static/search-focus.js"></script>

  58.             <script type="text/javascript" src="../_static/themetoggle.js"></script> 

  59. 

  60.   </head>

  61. <body>

  62. <div class="mobile-nav">

  63.     <input type="checkbox" id="menuToggler" class="toggler__input" aria-controls="navigation"

  64.            aria-pressed="false" aria-expanded="false" role="button" aria-label="Menu" />

  65.     <nav class="nav-content" role="navigation">

  66.         <label for="menuToggler" class="toggler__label">

  67.             <span></span>

  68.         </label>

  69.         <span class="nav-items-wrapper">

  70.             <a href="https://www.python.org/" class="nav-logo">

  71.                 <img src="../_static/py.svg" alt="Python logo"/>

  72.             </a>

  73.             <span class="version_switcher_placeholder"></span>

  74.             <form role="search" class="search" action="../search.html" method="get">

  75.                 <svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 24 24" class="search-icon">

  76.                     <path fill-rule="nonzero" fill="currentColor" d="M15.5 14h-.79l-.28-.27a6.5 6.5 0 001.48-5.34c-.47-2.78-2.79-5-5.59-5.34a6.505 6.505 0 00-7.27 7.27c.34 2.8 2.56 5.12 5.34 5.59a6.5 6.5 0 005.34-1.48l.27.28v.79l4.25 4.25c.41.41 1.08.41 1.49 0 .41-.41.41-1.08 0-1.49L15.5 14zm-6 0C7.01 14 5 11.99 5 9.5S7.01 5 9.5 5 14 7.01 14 9.5 11.99 14 9.5 14z"></path>

  77.                 </svg>

  78.                 <input placeholder="Quick search" aria-label="Quick search" type="search" name="q" />

  79.                 <input type="submit" value="Go"/>

  80.             </form>

  81.         </span>

  82.     </nav>

  83.     <div class="menu-wrapper">

  84.         <nav class="menu" role="navigation" aria-label="main navigation">

  85.             <div class="language_switcher_placeholder"></div>

  86.             

  87. <label class="theme-selector-label">

  88.     Theme

  89.     <select class="theme-selector" oninput="activateTheme(this.value)">

  90.         <option value="auto" selected>Auto</option>

  91.         <option value="light">Light</option>

  92.         <option value="dark">Dark</option>

  93.     </select>

  94. </label>

  95.   <div>

  96.     <h3><a href="../contents.html">Table of Contents</a></h3>

  97.     <ul>

  98. <li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">graphlib</span></code> — Functionality to operate with graph-like structures</a><ul>

  99. <li><a class="reference internal" href="#exceptions">Exceptions</a></li>

  100. </ul>

  101. </li>

  102. </ul>

  103. 

  104.   </div>

  105.   <div>

  106.     <h4>Previous topic</h4>

  107.     <p class="topless"><a href="enum.html"

  108.                           title="previous chapter"><code class="xref py py-mod docutils literal notranslate"><span class="pre">enum</span></code> — Support for enumerations</a></p>

  109.   </div>

  110.   <div>

  111.     <h4>Next topic</h4>

  112.     <p class="topless"><a href="numeric.html"

  113.                           title="next chapter">Numeric and Mathematical Modules</a></p>

  114.   </div>

  115.   <div role="note" aria-label="source link">

  116.     <h3>This Page</h3>

  117.     <ul class="this-page-menu">

  118.       <li><a href="../bugs.html">Report a Bug</a></li>

  119.       <li>

  120.         <a href="https://github.com/python/cpython/blob/main/Doc/library/graphlib.rst"

  121.             rel="nofollow">Show Source

  122.         </a>

  123.       </li>

  124.     </ul>

  125.   </div>

  126.         </nav>

  127.     </div>

  128. </div>

  129. 

  130.   

  131.     <div class="related" role="navigation" aria-label="related navigation">

  132.       <h3>Navigation</h3>

  133.       <ul>

  134.         <li class="right" style="margin-right: 10px">

  135.           <a href="../genindex.html" title="General Index"

  136.              accesskey="I">index</a></li>

  137.         <li class="right" >

  138.           <a href="../py-modindex.html" title="Python Module Index"

  139.              >modules</a> |</li>

  140.         <li class="right" >

  141.           <a href="numeric.html" title="Numeric and Mathematical Modules"

  142.              accesskey="N">next</a> |</li>

  143.         <li class="right" >

  144.           <a href="enum.html" title="enum — Support for enumerations"

  145.              accesskey="P">previous</a> |</li>

  146. 

  147.           <li><img src="../_static/py.svg" alt="Python logo" style="vertical-align: middle; margin-top: -1px"/></li>

  148.           <li><a href="https://www.python.org/">Python</a> &#187;</li>

  149.           <li class="switchers">

  150.             <div class="language_switcher_placeholder"></div>

  151.             <div class="version_switcher_placeholder"></div>

  152.           </li>

  153.           <li>

  154.               

  155.           </li>

  156.     <li id="cpython-language-and-version">

  157.       <a href="../index.html">3.12.3 Documentation</a> &#187;

  158.     </li>

  159. 

  160.           <li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> &#187;</li>

  161.           <li class="nav-item nav-item-2"><a href="datatypes.html" accesskey="U">Data Types</a> &#187;</li>

  162.         <li class="nav-item nav-item-this"><a href=""><code class="xref py py-mod docutils literal notranslate"><span class="pre">graphlib</span></code> — Functionality to operate with graph-like structures</a></li>

  163.                 <li class="right">

  164.                     

  165. 

  166.     <div class="inline-search" role="search">

  167.         <form class="inline-search" action="../search.html" method="get">

  168.           <input placeholder="Quick search" aria-label="Quick search" type="search" name="q" id="search-box" />

  169.           <input type="submit" value="Go" />

  170.         </form>

  171.     </div>

  172.                      |

  173.                 </li>

  174.             <li class="right">

  175. <label class="theme-selector-label">

  176.     Theme

  177.     <select class="theme-selector" oninput="activateTheme(this.value)">

  178.         <option value="auto" selected>Auto</option>

  179.         <option value="light">Light</option>

  180.         <option value="dark">Dark</option>

  181.     </select>

  182. </label> |</li>

  183.             

  184.       </ul>

  185.     </div>    

  186. 

  187.     <div class="document">

  188.       <div class="documentwrapper">

  189.         <div class="bodywrapper">

  190.           <div class="body" role="main">

  191.             

  192.   <section id="module-graphlib">

  193. <span id="graphlib-functionality-to-operate-with-graph-like-structures"></span><h1><a class="reference internal" href="#module-graphlib" title="graphlib: Functionality to operate with graph-like structures"><code class="xref py py-mod docutils literal notranslate"><span class="pre">graphlib</span></code></a> — Functionality to operate with graph-like structures<a class="headerlink" href="#module-graphlib" title="Link to this heading">¶</a></h1>

  194. <p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.12/Lib/graphlib.py">Lib/graphlib.py</a></p>

  195. <hr class="docutils" />

  196. <dl class="py class">

  197. <dt class="sig sig-object py" id="graphlib.TopologicalSorter">

  198. <em class="property"><span class="pre">class</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">graphlib.</span></span><span class="sig-name descname"><span class="pre">TopologicalSorter</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">graph</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#graphlib.TopologicalSorter" title="Link to this definition">¶</a></dt>

  199. <dd><p>Provides functionality to topologically sort a graph of <a class="reference internal" href="../glossary.html#term-hashable"><span class="xref std std-term">hashable</span></a> nodes.</p>

  200. <p>A topological order is a linear ordering of the vertices in a graph such that

  201. for every directed edge u -&gt; v from vertex u to vertex v, vertex u comes

  202. before vertex v in the ordering. For instance, the vertices of the graph may

  203. represent tasks to be performed, and the edges may represent constraints that

  204. one task must be performed before another; in this example, a topological

  205. ordering is just a valid sequence for the tasks. A complete topological

  206. ordering is possible if and only if the graph has no directed cycles, that

  207. is, if it is a directed acyclic graph.</p>

  208. <p>If the optional <em>graph</em> argument is provided it must be a dictionary

  209. representing a directed acyclic graph where the keys are nodes and the values

  210. are iterables of all predecessors of that node in the graph (the nodes that

  211. have edges that point to the value in the key). Additional nodes can be added

  212. to the graph using the <a class="reference internal" href="#graphlib.TopologicalSorter.add" title="graphlib.TopologicalSorter.add"><code class="xref py py-meth docutils literal notranslate"><span class="pre">add()</span></code></a> method.</p>

  213. <p>In the general case, the steps required to perform the sorting of a given

  214. graph are as follows:</p>

  215. <ul class="simple">

  216. <li><p>Create an instance of the <a class="reference internal" href="#graphlib.TopologicalSorter" title="graphlib.TopologicalSorter"><code class="xref py py-class docutils literal notranslate"><span class="pre">TopologicalSorter</span></code></a> with an optional

  217. initial graph.</p></li>

  218. <li><p>Add additional nodes to the graph.</p></li>

  219. <li><p>Call <a class="reference internal" href="#graphlib.TopologicalSorter.prepare" title="graphlib.TopologicalSorter.prepare"><code class="xref py py-meth docutils literal notranslate"><span class="pre">prepare()</span></code></a> on the graph.</p></li>

  220. <li><p>While <a class="reference internal" href="#graphlib.TopologicalSorter.is_active" title="graphlib.TopologicalSorter.is_active"><code class="xref py py-meth docutils literal notranslate"><span class="pre">is_active()</span></code></a> is <code class="docutils literal notranslate"><span class="pre">True</span></code>, iterate over

  221. the nodes returned by <a class="reference internal" href="#graphlib.TopologicalSorter.get_ready" title="graphlib.TopologicalSorter.get_ready"><code class="xref py py-meth docutils literal notranslate"><span class="pre">get_ready()</span></code></a> and

  222. process them. Call <a class="reference internal" href="#graphlib.TopologicalSorter.done" title="graphlib.TopologicalSorter.done"><code class="xref py py-meth docutils literal notranslate"><span class="pre">done()</span></code></a> on each node as it

  223. finishes processing.</p></li>

  224. </ul>

  225. <p>In case just an immediate sorting of the nodes in the graph is required and

  226. no parallelism is involved, the convenience method

  227. <a class="reference internal" href="#graphlib.TopologicalSorter.static_order" title="graphlib.TopologicalSorter.static_order"><code class="xref py py-meth docutils literal notranslate"><span class="pre">TopologicalSorter.static_order()</span></code></a> can be used directly:</p>

  228. <div class="highlight-pycon notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">graph</span> <span class="o">=</span> <span class="p">{</span><span class="s2">&quot;D&quot;</span><span class="p">:</span> <span class="p">{</span><span class="s2">&quot;B&quot;</span><span class="p">,</span> <span class="s2">&quot;C&quot;</span><span class="p">},</span> <span class="s2">&quot;C&quot;</span><span class="p">:</span> <span class="p">{</span><span class="s2">&quot;A&quot;</span><span class="p">},</span> <span class="s2">&quot;B&quot;</span><span class="p">:</span> <span class="p">{</span><span class="s2">&quot;A&quot;</span><span class="p">}}</span>

  229. <span class="gp">&gt;&gt;&gt; </span><span class="n">ts</span> <span class="o">=</span> <span class="n">TopologicalSorter</span><span class="p">(</span><span class="n">graph</span><span class="p">)</span>

  230. <span class="gp">&gt;&gt;&gt; </span><span class="nb">tuple</span><span class="p">(</span><span class="n">ts</span><span class="o">.</span><span class="n">static_order</span><span class="p">())</span>

  231. <span class="go">(&#39;A&#39;, &#39;C&#39;, &#39;B&#39;, &#39;D&#39;)</span>

  232. </pre></div>

  233. </div>

  234. <p>The class is designed to easily support parallel processing of the nodes as

  235. they become ready. For instance:</p>

  236. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">topological_sorter</span> <span class="o">=</span> <span class="n">TopologicalSorter</span><span class="p">()</span>

  237. 

  238. <span class="c1"># Add nodes to &#39;topological_sorter&#39;...</span>

  239. 

  240. <span class="n">topological_sorter</span><span class="o">.</span><span class="n">prepare</span><span class="p">()</span>

  241. <span class="k">while</span> <span class="n">topological_sorter</span><span class="o">.</span><span class="n">is_active</span><span class="p">():</span>

  242.     <span class="k">for</span> <span class="n">node</span> <span class="ow">in</span> <span class="n">topological_sorter</span><span class="o">.</span><span class="n">get_ready</span><span class="p">():</span>

  243.         <span class="c1"># Worker threads or processes take nodes to work on off the</span>

  244.         <span class="c1"># &#39;task_queue&#39; queue.</span>

  245.         <span class="n">task_queue</span><span class="o">.</span><span class="n">put</span><span class="p">(</span><span class="n">node</span><span class="p">)</span>

  246. 

  247.     <span class="c1"># When the work for a node is done, workers put the node in</span>

  248.     <span class="c1"># &#39;finalized_tasks_queue&#39; so we can get more nodes to work on.</span>

  249.     <span class="c1"># The definition of &#39;is_active()&#39; guarantees that, at this point, at</span>

  250.     <span class="c1"># least one node has been placed on &#39;task_queue&#39; that hasn&#39;t yet</span>

  251.     <span class="c1"># been passed to &#39;done()&#39;, so this blocking &#39;get()&#39; must (eventually)</span>

  252.     <span class="c1"># succeed.  After calling &#39;done()&#39;, we loop back to call &#39;get_ready()&#39;</span>

  253.     <span class="c1"># again, so put newly freed nodes on &#39;task_queue&#39; as soon as</span>

  254.     <span class="c1"># logically possible.</span>

  255.     <span class="n">node</span> <span class="o">=</span> <span class="n">finalized_tasks_queue</span><span class="o">.</span><span class="n">get</span><span class="p">()</span>

  256.     <span class="n">topological_sorter</span><span class="o">.</span><span class="n">done</span><span class="p">(</span><span class="n">node</span><span class="p">)</span>

  257. </pre></div>

  258. </div>

  259. <dl class="py method">

  260. <dt class="sig sig-object py" id="graphlib.TopologicalSorter.add">

  261. <span class="sig-name descname"><span class="pre">add</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">node</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">*</span></span><span class="n"><span class="pre">predecessors</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#graphlib.TopologicalSorter.add" title="Link to this definition">¶</a></dt>

  262. <dd><p>Add a new node and its predecessors to the graph. Both the <em>node</em> and all

  263. elements in <em>predecessors</em> must be <a class="reference internal" href="../glossary.html#term-hashable"><span class="xref std std-term">hashable</span></a>.</p>

  264. <p>If called multiple times with the same node argument, the set of

  265. dependencies will be the union of all dependencies passed in.</p>

  266. <p>It is possible to add a node with no dependencies (<em>predecessors</em> is not

  267. provided) or to provide a dependency twice. If a node that has not been

  268. provided before is included among <em>predecessors</em> it will be automatically

  269. added to the graph with no predecessors of its own.</p>

  270. <p>Raises <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> if called after <a class="reference internal" href="#graphlib.TopologicalSorter.prepare" title="graphlib.TopologicalSorter.prepare"><code class="xref py py-meth docutils literal notranslate"><span class="pre">prepare()</span></code></a>.</p>

  271. </dd></dl>

  272. 

  273. <dl class="py method">

  274. <dt class="sig sig-object py" id="graphlib.TopologicalSorter.prepare">

  275. <span class="sig-name descname"><span class="pre">prepare</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#graphlib.TopologicalSorter.prepare" title="Link to this definition">¶</a></dt>

  276. <dd><p>Mark the graph as finished and check for cycles in the graph. If any cycle

  277. is detected, <a class="reference internal" href="#graphlib.CycleError" title="graphlib.CycleError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">CycleError</span></code></a> will be raised, but

  278. <a class="reference internal" href="#graphlib.TopologicalSorter.get_ready" title="graphlib.TopologicalSorter.get_ready"><code class="xref py py-meth docutils literal notranslate"><span class="pre">get_ready()</span></code></a> can still be used to obtain as many

  279. nodes as possible until cycles block more progress. After a call to this

  280. function, the graph cannot be modified, and therefore no more nodes can be

  281. added using <a class="reference internal" href="#graphlib.TopologicalSorter.add" title="graphlib.TopologicalSorter.add"><code class="xref py py-meth docutils literal notranslate"><span class="pre">add()</span></code></a>.</p>

  282. </dd></dl>

  283. 

  284. <dl class="py method">

  285. <dt class="sig sig-object py" id="graphlib.TopologicalSorter.is_active">

  286. <span class="sig-name descname"><span class="pre">is_active</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#graphlib.TopologicalSorter.is_active" title="Link to this definition">¶</a></dt>

  287. <dd><p>Returns <code class="docutils literal notranslate"><span class="pre">True</span></code> if more progress can be made and <code class="docutils literal notranslate"><span class="pre">False</span></code> otherwise.

  288. Progress can be made if cycles do not block the resolution and either

  289. there are still nodes ready that haven’t yet been returned by

  290. <a class="reference internal" href="#graphlib.TopologicalSorter.get_ready" title="graphlib.TopologicalSorter.get_ready"><code class="xref py py-meth docutils literal notranslate"><span class="pre">TopologicalSorter.get_ready()</span></code></a> or the number of nodes marked

  291. <a class="reference internal" href="#graphlib.TopologicalSorter.done" title="graphlib.TopologicalSorter.done"><code class="xref py py-meth docutils literal notranslate"><span class="pre">TopologicalSorter.done()</span></code></a> is less than the number that have been

  292. returned by <a class="reference internal" href="#graphlib.TopologicalSorter.get_ready" title="graphlib.TopologicalSorter.get_ready"><code class="xref py py-meth docutils literal notranslate"><span class="pre">TopologicalSorter.get_ready()</span></code></a>.</p>

  293. <p>The <a class="reference internal" href="../reference/datamodel.html#object.__bool__" title="object.__bool__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__bool__()</span></code></a> method of this class defers to

  294. this function, so instead of:</p>

  295. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">if</span> <span class="n">ts</span><span class="o">.</span><span class="n">is_active</span><span class="p">():</span>

  296.     <span class="o">...</span>

  297. </pre></div>

  298. </div>

  299. <p>it is possible to simply do:</p>

  300. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">if</span> <span class="n">ts</span><span class="p">:</span>

  301.     <span class="o">...</span>

  302. </pre></div>

  303. </div>

  304. <p>Raises <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> if called without calling

  305. <a class="reference internal" href="#graphlib.TopologicalSorter.prepare" title="graphlib.TopologicalSorter.prepare"><code class="xref py py-meth docutils literal notranslate"><span class="pre">prepare()</span></code></a> previously.</p>

  306. </dd></dl>

  307. 

  308. <dl class="py method">

  309. <dt class="sig sig-object py" id="graphlib.TopologicalSorter.done">

  310. <span class="sig-name descname"><span class="pre">done</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="o"><span class="pre">*</span></span><span class="n"><span class="pre">nodes</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#graphlib.TopologicalSorter.done" title="Link to this definition">¶</a></dt>

  311. <dd><p>Marks a set of nodes returned by <a class="reference internal" href="#graphlib.TopologicalSorter.get_ready" title="graphlib.TopologicalSorter.get_ready"><code class="xref py py-meth docutils literal notranslate"><span class="pre">TopologicalSorter.get_ready()</span></code></a> as

  312. processed, unblocking any successor of each node in <em>nodes</em> for being

  313. returned in the future by a call to <a class="reference internal" href="#graphlib.TopologicalSorter.get_ready" title="graphlib.TopologicalSorter.get_ready"><code class="xref py py-meth docutils literal notranslate"><span class="pre">TopologicalSorter.get_ready()</span></code></a>.</p>

  314. <p>Raises <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> if any node in <em>nodes</em> has already been marked as

  315. processed by a previous call to this method or if a node was not added to

  316. the graph by using <a class="reference internal" href="#graphlib.TopologicalSorter.add" title="graphlib.TopologicalSorter.add"><code class="xref py py-meth docutils literal notranslate"><span class="pre">TopologicalSorter.add()</span></code></a>, if called without

  317. calling <a class="reference internal" href="#graphlib.TopologicalSorter.prepare" title="graphlib.TopologicalSorter.prepare"><code class="xref py py-meth docutils literal notranslate"><span class="pre">prepare()</span></code></a> or if node has not yet been

  318. returned by <a class="reference internal" href="#graphlib.TopologicalSorter.get_ready" title="graphlib.TopologicalSorter.get_ready"><code class="xref py py-meth docutils literal notranslate"><span class="pre">get_ready()</span></code></a>.</p>

  319. </dd></dl>

  320. 

  321. <dl class="py method">

  322. <dt class="sig sig-object py" id="graphlib.TopologicalSorter.get_ready">

  323. <span class="sig-name descname"><span class="pre">get_ready</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#graphlib.TopologicalSorter.get_ready" title="Link to this definition">¶</a></dt>

  324. <dd><p>Returns a <code class="docutils literal notranslate"><span class="pre">tuple</span></code> with all the nodes that are ready. Initially it

  325. returns all nodes with no predecessors, and once those are marked as

  326. processed by calling <a class="reference internal" href="#graphlib.TopologicalSorter.done" title="graphlib.TopologicalSorter.done"><code class="xref py py-meth docutils literal notranslate"><span class="pre">TopologicalSorter.done()</span></code></a>, further calls will

  327. return all new nodes that have all their predecessors already processed.

  328. Once no more progress can be made, empty tuples are returned.</p>

  329. <p>Raises <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> if called without calling

  330. <a class="reference internal" href="#graphlib.TopologicalSorter.prepare" title="graphlib.TopologicalSorter.prepare"><code class="xref py py-meth docutils literal notranslate"><span class="pre">prepare()</span></code></a> previously.</p>

  331. </dd></dl>

  332. 

  333. <dl class="py method">

  334. <dt class="sig sig-object py" id="graphlib.TopologicalSorter.static_order">

  335. <span class="sig-name descname"><span class="pre">static_order</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#graphlib.TopologicalSorter.static_order" title="Link to this definition">¶</a></dt>

  336. <dd><p>Returns an iterator object which will iterate over nodes in a topological

  337. order. When using this method, <a class="reference internal" href="#graphlib.TopologicalSorter.prepare" title="graphlib.TopologicalSorter.prepare"><code class="xref py py-meth docutils literal notranslate"><span class="pre">prepare()</span></code></a> and

  338. <a class="reference internal" href="#graphlib.TopologicalSorter.done" title="graphlib.TopologicalSorter.done"><code class="xref py py-meth docutils literal notranslate"><span class="pre">done()</span></code></a> should not be called. This method is

  339. equivalent to:</p>

  340. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">def</span> <span class="nf">static_order</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>

  341.     <span class="bp">self</span><span class="o">.</span><span class="n">prepare</span><span class="p">()</span>

  342.     <span class="k">while</span> <span class="bp">self</span><span class="o">.</span><span class="n">is_active</span><span class="p">():</span>

  343.         <span class="n">node_group</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">get_ready</span><span class="p">()</span>

  344.         <span class="k">yield from</span> <span class="n">node_group</span>

  345.         <span class="bp">self</span><span class="o">.</span><span class="n">done</span><span class="p">(</span><span class="o">*</span><span class="n">node_group</span><span class="p">)</span>

  346. </pre></div>

  347. </div>

  348. <p>The particular order that is returned may depend on the specific order in

  349. which the items were inserted in the graph. For example:</p>

  350. <div class="highlight-pycon notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">ts</span> <span class="o">=</span> <span class="n">TopologicalSorter</span><span class="p">()</span>

  351. <span class="gp">&gt;&gt;&gt; </span><span class="n">ts</span><span class="o">.</span><span class="n">add</span><span class="p">(</span><span class="mi">3</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>

  352. <span class="gp">&gt;&gt;&gt; </span><span class="n">ts</span><span class="o">.</span><span class="n">add</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">)</span>

  353. <span class="gp">&gt;&gt;&gt; </span><span class="nb">print</span><span class="p">([</span><span class="o">*</span><span class="n">ts</span><span class="o">.</span><span class="n">static_order</span><span class="p">()])</span>

  354. <span class="go">[2, 0, 1, 3]</span>

  355. 

  356. <span class="gp">&gt;&gt;&gt; </span><span class="n">ts2</span> <span class="o">=</span> <span class="n">TopologicalSorter</span><span class="p">()</span>

  357. <span class="gp">&gt;&gt;&gt; </span><span class="n">ts2</span><span class="o">.</span><span class="n">add</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">)</span>

  358. <span class="gp">&gt;&gt;&gt; </span><span class="n">ts2</span><span class="o">.</span><span class="n">add</span><span class="p">(</span><span class="mi">3</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>

  359. <span class="gp">&gt;&gt;&gt; </span><span class="nb">print</span><span class="p">([</span><span class="o">*</span><span class="n">ts2</span><span class="o">.</span><span class="n">static_order</span><span class="p">()])</span>

  360. <span class="go">[0, 2, 1, 3]</span>

  361. </pre></div>

  362. </div>

  363. <p>This is due to the fact that “0” and “2” are in the same level in the

  364. graph (they would have been returned in the same call to

  365. <a class="reference internal" href="#graphlib.TopologicalSorter.get_ready" title="graphlib.TopologicalSorter.get_ready"><code class="xref py py-meth docutils literal notranslate"><span class="pre">get_ready()</span></code></a>) and the order between them is

  366. determined by the order of insertion.</p>

  367. <p>If any cycle is detected, <a class="reference internal" href="#graphlib.CycleError" title="graphlib.CycleError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">CycleError</span></code></a> will be raised.</p>

  368. </dd></dl>

  369. 

  370. <div class="versionadded">

  371. <p><span class="versionmodified added">New in version 3.9.</span></p>

  372. </div>

  373. </dd></dl>

  374. 

  375. <section id="exceptions">

  376. <h2>Exceptions<a class="headerlink" href="#exceptions" title="Link to this heading">¶</a></h2>

  377. <p>The <a class="reference internal" href="#module-graphlib" title="graphlib: Functionality to operate with graph-like structures"><code class="xref py py-mod docutils literal notranslate"><span class="pre">graphlib</span></code></a> module defines the following exception classes:</p>

  378. <dl class="py exception">

  379. <dt class="sig sig-object py" id="graphlib.CycleError">

  380. <em class="property"><span class="pre">exception</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">graphlib.</span></span><span class="sig-name descname"><span class="pre">CycleError</span></span><a class="headerlink" href="#graphlib.CycleError" title="Link to this definition">¶</a></dt>

  381. <dd><p>Subclass of <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> raised by <a class="reference internal" href="#graphlib.TopologicalSorter.prepare" title="graphlib.TopologicalSorter.prepare"><code class="xref py py-meth docutils literal notranslate"><span class="pre">TopologicalSorter.prepare()</span></code></a> if cycles exist

  382. in the working graph. If multiple cycles exist, only one undefined choice among them will

  383. be reported and included in the exception.</p>

  384. <p>The detected cycle can be accessed via the second element in the <a class="reference internal" href="exceptions.html#BaseException.args" title="BaseException.args"><code class="xref py py-attr docutils literal notranslate"><span class="pre">args</span></code></a>

  385. attribute of the exception instance and consists in a list of nodes, such that each node is,

  386. in the graph, an immediate predecessor of the next node in the list. In the reported list,

  387. the first and the last node will be the same, to make it clear that it is cyclic.</p>

  388. </dd></dl>

  389. 

  390. </section>

  391. </section>

  392. 

  393. 

  394.             <div class="clearer"></div>

  395.           </div>

  396.         </div>

  397.       </div>

  398.       <div class="sphinxsidebar" role="navigation" aria-label="main navigation">

  399.         <div class="sphinxsidebarwrapper">

  400.   <div>

  401.     <h3><a href="../contents.html">Table of Contents</a></h3>

  402.     <ul>

  403. <li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">graphlib</span></code> — Functionality to operate with graph-like structures</a><ul>

  404. <li><a class="reference internal" href="#exceptions">Exceptions</a></li>

  405. </ul>

  406. </li>

  407. </ul>

  408. 

  409.   </div>

  410.   <div>

  411.     <h4>Previous topic</h4>

  412.     <p class="topless"><a href="enum.html"

  413.                           title="previous chapter"><code class="xref py py-mod docutils literal notranslate"><span class="pre">enum</span></code> — Support for enumerations</a></p>

  414.   </div>

  415.   <div>

  416.     <h4>Next topic</h4>

  417.     <p class="topless"><a href="numeric.html"

  418.                           title="next chapter">Numeric and Mathematical Modules</a></p>

  419.   </div>

  420.   <div role="note" aria-label="source link">

  421.     <h3>This Page</h3>

  422.     <ul class="this-page-menu">

  423.       <li><a href="../bugs.html">Report a Bug</a></li>

  424.       <li>

  425.         <a href="https://github.com/python/cpython/blob/main/Doc/library/graphlib.rst"

  426.             rel="nofollow">Show Source

  427.         </a>

  428.       </li>

  429.     </ul>

  430.   </div>

  431.         </div>

  432. <div id="sidebarbutton" title="Collapse sidebar">

  433. <span>«</span>

  434. </div>

  435. 

  436.       </div>

  437.       <div class="clearer"></div>

  438.     </div>  

  439.     <div class="related" role="navigation" aria-label="related navigation">

  440.       <h3>Navigation</h3>

  441.       <ul>

  442.         <li class="right" style="margin-right: 10px">

  443.           <a href="../genindex.html" title="General Index"

  444.              >index</a></li>

  445.         <li class="right" >

  446.           <a href="../py-modindex.html" title="Python Module Index"

  447.              >modules</a> |</li>

  448.         <li class="right" >

  449.           <a href="numeric.html" title="Numeric and Mathematical Modules"

  450.              >next</a> |</li>

  451.         <li class="right" >

  452.           <a href="enum.html" title="enum — Support for enumerations"

  453.              >previous</a> |</li>

  454. 

  455.           <li><img src="../_static/py.svg" alt="Python logo" style="vertical-align: middle; margin-top: -1px"/></li>

  456.           <li><a href="https://www.python.org/">Python</a> &#187;</li>

  457.           <li class="switchers">

  458.             <div class="language_switcher_placeholder"></div>

  459.             <div class="version_switcher_placeholder"></div>

  460.           </li>

  461.           <li>

  462.               

  463.           </li>

  464.     <li id="cpython-language-and-version">

  465.       <a href="../index.html">3.12.3 Documentation</a> &#187;

  466.     </li>

  467. 

  468.           <li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> &#187;</li>

  469.           <li class="nav-item nav-item-2"><a href="datatypes.html" >Data Types</a> &#187;</li>

  470.         <li class="nav-item nav-item-this"><a href=""><code class="xref py py-mod docutils literal notranslate"><span class="pre">graphlib</span></code> — Functionality to operate with graph-like structures</a></li>

  471.                 <li class="right">

  472.                     

  473. 

  474.     <div class="inline-search" role="search">

  475.         <form class="inline-search" action="../search.html" method="get">

  476.           <input placeholder="Quick search" aria-label="Quick search" type="search" name="q" id="search-box" />

  477.           <input type="submit" value="Go" />

  478.         </form>

  479.     </div>

  480.                      |

  481.                 </li>

  482.             <li class="right">

  483. <label class="theme-selector-label">

  484.     Theme

  485.     <select class="theme-selector" oninput="activateTheme(this.value)">

  486.         <option value="auto" selected>Auto</option>

  487.         <option value="light">Light</option>

  488.         <option value="dark">Dark</option>

  489.     </select>

  490. </label> |</li>

  491.             

  492.       </ul>

  493.     </div>  

  494.     <div class="footer">

  495.     &copy; 

  496.       <a href="../copyright.html">

  497.     

  498.     Copyright

  499.     

  500.       </a>

  501.      2001-2024, Python Software Foundation.

  502.     <br />

  503.     This page is licensed under the Python Software Foundation License Version 2.

  504.     <br />

  505.     Examples, recipes, and other code in the documentation are additionally licensed under the Zero Clause BSD License.

  506.     <br />

  507.     

  508.       See <a href="/license.html">History and License</a> for more information.<br />

  509.     

  510.     

  511.     <br />

  512. 

  513.     The Python Software Foundation is a non-profit corporation.

  514. <a href="https://www.python.org/psf/donations/">Please donate.</a>

  515. <br />

  516.     <br />

  517.       Last updated on Apr 09, 2024 (13:47 UTC).

  518.     

  519.       <a href="/bugs.html">Found a bug</a>?

  520.     

  521.     <br />

  522. 

  523.     Created using <a href="https://www.sphinx-doc.org/">Sphinx</a> 7.2.6.

  524.     </div>

  525. 

  526.   </body>

  527. </html>
上海开阖软件有限公司 沪ICP备12045867号-1