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charset=utf-8" /> <title>14.1. csv — CSV File Reading and Writing — Python 3.7.0 說明文件</title> <link rel="stylesheet" href="../_static/pydoctheme.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/underscore.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <script type="text/javascript" src="../_static/translations.js"></script> <script type="text/javascript" src="../_static/sidebar.js"></script> <link rel="search" type="application/opensearchdescription+xml" title="在 Python 3.7.0 說明文件 中搜尋" href="../_static/opensearch.xml"/> <link rel="author" title="關於這些文件" href="../about.html" /> <link rel="index" title="索引" href="../genindex.html" /> <link rel="search" title="搜尋" href="../search.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="next" title="14.2. configparser — Configuration file parser" href="configparser.html" /> <link rel="prev" title="14. 檔案格式" href="fileformats.html" /> <link rel="shortcut icon" type="image/png" href="../_static/py.png" /> <link rel="canonical" href="https://docs.python.org/3/library/csv.html" /> <script type="text/javascript" src="../_static/copybutton.js"></script> <script type="text/javascript" src="../_static/switchers.js"></script> </head><body> <div class="related" role="navigation" aria-label="related navigation"> <h3>瀏覽</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" accesskey="I">索引</a></li> <li class="right" > <a href="../py-modindex.html" title="Python 模組索引" >模組</a> |</li> <li class="right" > <a href="configparser.html" title="14.2. configparser — Configuration file parser" accesskey="N">下一頁</a> |</li> <li class="right" > <a href="fileformats.html" title="14. 檔案格式" accesskey="P">上一頁</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <span class="language_switcher_placeholder">zh_TW</span> <span class="version_switcher_placeholder">3.7.0</span> <a href="../index.html">Documentation </a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >Python 標準函式庫 (Standard Library)</a> »</li> <li class="nav-item nav-item-2"><a href="fileformats.html" accesskey="U">14. 檔案格式</a> »</li> <li class="right"> <div class="inline-search" style="display: none" role="search"> <form class="inline-search" action="../search.html" method="get"> <input placeholder="Quick search" type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <script type="text/javascript">$('.inline-search').show(0);</script> | </li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body" role="main"> <div class="section" id="module-csv"> <span id="csv-csv-file-reading-and-writing"></span><h1>14.1. <a class="reference internal" href="#module-csv" title="csv: Write and read tabular data to and from delimited files."><code class="xref py py-mod docutils literal notranslate"><span class="pre">csv</span></code></a> — CSV File Reading and Writing<a class="headerlink" href="#module-csv" title="本標題的永久連結">¶</a></h1> <p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.7/Lib/csv.py">Lib/csv.py</a></p> <hr class="docutils" id="index-0" /> <p>The so-called CSV (Comma Separated Values) format is the most common import and export format for spreadsheets and databases. CSV format was used for many years prior to attempts to describe the format in a standardized way in <span class="target" id="index-1"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc4180.html"><strong>RFC 4180</strong></a>. The lack of a well-defined standard means that subtle differences often exist in the data produced and consumed by different applications. These differences can make it annoying to process CSV files from multiple sources. Still, while the delimiters and quoting characters vary, the overall format is similar enough that it is possible to write a single module which can efficiently manipulate such data, hiding the details of reading and writing the data from the programmer.</p> <p>The <a class="reference internal" href="#module-csv" title="csv: Write and read tabular data to and from delimited files."><code class="xref py py-mod docutils literal notranslate"><span class="pre">csv</span></code></a> module implements classes to read and write tabular data in CSV format. It allows programmers to say, 「write this data in the format preferred by Excel,」 or 「read data from this file which was generated by Excel,」 without knowing the precise details of the CSV format used by Excel. Programmers can also describe the CSV formats understood by other applications or define their own special-purpose CSV formats.</p> <p>The <a class="reference internal" href="#module-csv" title="csv: Write and read tabular data to and from delimited files."><code class="xref py py-mod docutils literal notranslate"><span class="pre">csv</span></code></a> module’s <a class="reference internal" href="#csv.reader" title="csv.reader"><code class="xref py py-class docutils literal notranslate"><span class="pre">reader</span></code></a> and <a class="reference internal" href="#csv.writer" title="csv.writer"><code class="xref py py-class docutils literal notranslate"><span class="pre">writer</span></code></a> objects read and write sequences. Programmers can also read and write data in dictionary form using the <a class="reference internal" href="#csv.DictReader" title="csv.DictReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">DictReader</span></code></a> and <a class="reference internal" href="#csv.DictWriter" title="csv.DictWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">DictWriter</span></code></a> classes.</p> <div class="admonition seealso"> <p class="first admonition-title">也參考</p> <dl class="last docutils"> <dt><span class="target" id="index-2"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0305"><strong>PEP 305</strong></a> - CSV File API</dt> <dd>The Python Enhancement Proposal which proposed this addition to Python.</dd> </dl> </div> <div class="section" id="module-contents"> <span id="csv-contents"></span><h2>14.1.1. Module Contents<a class="headerlink" href="#module-contents" title="本標題的永久連結">¶</a></h2> <p>The <a class="reference internal" href="#module-csv" title="csv: Write and read tabular data to and from delimited files."><code class="xref py py-mod docutils literal notranslate"><span class="pre">csv</span></code></a> module defines the following functions:</p> <span class="target" id="index-3"></span><dl class="function"> <dt id="csv.reader"> <code class="descclassname">csv.</code><code class="descname">reader</code><span class="sig-paren">(</span><em>csvfile</em>, <em>dialect='excel'</em>, <em>**fmtparams</em><span class="sig-paren">)</span><a class="headerlink" href="#csv.reader" title="本定義的永久連結">¶</a></dt> <dd><p>Return a reader object which will iterate over lines in the given <em>csvfile</em>. <em>csvfile</em> can be any object which supports the <a class="reference internal" href="../glossary.html#term-iterator"><span class="xref std std-term">iterator</span></a> protocol and returns a string each time its <code class="xref py py-meth docutils literal notranslate"><span class="pre">__next__()</span></code> method is called — <a class="reference internal" href="../glossary.html#term-file-object"><span class="xref std std-term">file objects</span></a> and list objects are both suitable. If <em>csvfile</em> is a file object, it should be opened with <code class="docutils literal notranslate"><span class="pre">newline=''</span></code>. <a class="footnote-reference" href="#id3" id="id1">[1]</a> An optional <em>dialect</em> parameter can be given which is used to define a set of parameters specific to a particular CSV dialect. It may be an instance of a subclass of the <a class="reference internal" href="#csv.Dialect" title="csv.Dialect"><code class="xref py py-class docutils literal notranslate"><span class="pre">Dialect</span></code></a> class or one of the strings returned by the <a class="reference internal" href="#csv.list_dialects" title="csv.list_dialects"><code class="xref py py-func docutils literal notranslate"><span class="pre">list_dialects()</span></code></a> function. The other optional <em>fmtparams</em> keyword arguments can be given to override individual formatting parameters in the current dialect. For full details about the dialect and formatting parameters, see section <a class="reference internal" href="#csv-fmt-params"><span class="std std-ref">Dialects and Formatting Parameters</span></a>.</p> <p>Each row read from the csv file is returned as a list of strings. No automatic data type conversion is performed unless the <code class="docutils literal notranslate"><span class="pre">QUOTE_NONNUMERIC</span></code> format option is specified (in which case unquoted fields are transformed into floats).</p> <p>A short usage example:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">csv</span> <span class="gp">>>> </span><span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">'eggs.csv'</span><span class="p">,</span> <span class="n">newline</span><span class="o">=</span><span class="s1">''</span><span class="p">)</span> <span class="k">as</span> <span class="n">csvfile</span><span class="p">:</span> <span class="gp">... </span> <span class="n">spamreader</span> <span class="o">=</span> <span class="n">csv</span><span class="o">.</span><span class="n">reader</span><span class="p">(</span><span class="n">csvfile</span><span class="p">,</span> <span class="n">delimiter</span><span class="o">=</span><span class="s1">' '</span><span class="p">,</span> <span class="n">quotechar</span><span class="o">=</span><span class="s1">'|'</span><span class="p">)</span> <span class="gp">... </span> <span class="k">for</span> <span class="n">row</span> <span class="ow">in</span> <span class="n">spamreader</span><span class="p">:</span> <span class="gp">... </span> <span class="nb">print</span><span class="p">(</span><span class="s1">', '</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">row</span><span class="p">))</span> <span class="go">Spam, Spam, Spam, Spam, Spam, Baked Beans</span> <span class="go">Spam, Lovely Spam, Wonderful Spam</span> </pre></div> </div> </dd></dl> <dl class="function"> <dt id="csv.writer"> <code class="descclassname">csv.</code><code class="descname">writer</code><span class="sig-paren">(</span><em>csvfile</em>, <em>dialect='excel'</em>, <em>**fmtparams</em><span class="sig-paren">)</span><a class="headerlink" href="#csv.writer" title="本定義的永久連結">¶</a></dt> <dd><p>Return a writer object responsible for converting the user’s data into delimited strings on the given file-like object. <em>csvfile</em> can be any object with a <code class="xref py py-func docutils literal notranslate"><span class="pre">write()</span></code> method. If <em>csvfile</em> is a file object, it should be opened with <code class="docutils literal notranslate"><span class="pre">newline=''</span></code> <a class="footnote-reference" href="#id3" id="id2">[1]</a>. An optional <em>dialect</em> parameter can be given which is used to define a set of parameters specific to a particular CSV dialect. It may be an instance of a subclass of the <a class="reference internal" href="#csv.Dialect" title="csv.Dialect"><code class="xref py py-class docutils literal notranslate"><span class="pre">Dialect</span></code></a> class or one of the strings returned by the <a class="reference internal" href="#csv.list_dialects" title="csv.list_dialects"><code class="xref py py-func docutils literal notranslate"><span class="pre">list_dialects()</span></code></a> function. The other optional <em>fmtparams</em> keyword arguments can be given to override individual formatting parameters in the current dialect. For full details about the dialect and formatting parameters, see section <a class="reference internal" href="#csv-fmt-params"><span class="std std-ref">Dialects and Formatting Parameters</span></a>. To make it as easy as possible to interface with modules which implement the DB API, the value <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate"><span class="pre">None</span></code></a> is written as the empty string. While this isn’t a reversible transformation, it makes it easier to dump SQL NULL data values to CSV files without preprocessing the data returned from a <code class="docutils literal notranslate"><span class="pre">cursor.fetch*</span></code> call. All other non-string data are stringified with <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-func docutils literal notranslate"><span class="pre">str()</span></code></a> before being written.</p> <p>A short usage example:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">csv</span> <span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">'eggs.csv'</span><span class="p">,</span> <span class="s1">'w'</span><span class="p">,</span> <span class="n">newline</span><span class="o">=</span><span class="s1">''</span><span class="p">)</span> <span class="k">as</span> <span class="n">csvfile</span><span class="p">:</span> <span class="n">spamwriter</span> <span class="o">=</span> <span class="n">csv</span><span class="o">.</span><span class="n">writer</span><span class="p">(</span><span class="n">csvfile</span><span class="p">,</span> <span class="n">delimiter</span><span class="o">=</span><span class="s1">' '</span><span class="p">,</span> <span class="n">quotechar</span><span class="o">=</span><span class="s1">'|'</span><span class="p">,</span> <span class="n">quoting</span><span class="o">=</span><span class="n">csv</span><span class="o">.</span><span class="n">QUOTE_MINIMAL</span><span class="p">)</span> <span class="n">spamwriter</span><span class="o">.</span><span class="n">writerow</span><span class="p">([</span><span class="s1">'Spam'</span><span class="p">]</span> <span class="o">*</span> <span class="mi">5</span> <span class="o">+</span> <span class="p">[</span><span class="s1">'Baked Beans'</span><span class="p">])</span> <span class="n">spamwriter</span><span class="o">.</span><span class="n">writerow</span><span class="p">([</span><span class="s1">'Spam'</span><span class="p">,</span> <span class="s1">'Lovely Spam'</span><span class="p">,</span> <span class="s1">'Wonderful Spam'</span><span class="p">])</span> </pre></div> </div> </dd></dl> <dl class="function"> <dt id="csv.register_dialect"> <code class="descclassname">csv.</code><code class="descname">register_dialect</code><span class="sig-paren">(</span><em>name</em><span class="optional">[</span>, <em>dialect</em><span class="optional">[</span>, <em>**fmtparams</em><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#csv.register_dialect" title="本定義的永久連結">¶</a></dt> <dd><p>Associate <em>dialect</em> with <em>name</em>. <em>name</em> must be a string. The dialect can be specified either by passing a sub-class of <a class="reference internal" href="#csv.Dialect" title="csv.Dialect"><code class="xref py py-class docutils literal notranslate"><span class="pre">Dialect</span></code></a>, or by <em>fmtparams</em> keyword arguments, or both, with keyword arguments overriding parameters of the dialect. For full details about the dialect and formatting parameters, see section <a class="reference internal" href="#csv-fmt-params"><span class="std std-ref">Dialects and Formatting Parameters</span></a>.</p> </dd></dl> <dl class="function"> <dt id="csv.unregister_dialect"> <code class="descclassname">csv.</code><code class="descname">unregister_dialect</code><span class="sig-paren">(</span><em>name</em><span class="sig-paren">)</span><a class="headerlink" href="#csv.unregister_dialect" title="本定義的永久連結">¶</a></dt> <dd><p>Delete the dialect associated with <em>name</em> from the dialect registry. An <a class="reference internal" href="#csv.Error" title="csv.Error"><code class="xref py py-exc docutils literal notranslate"><span class="pre">Error</span></code></a> is raised if <em>name</em> is not a registered dialect name.</p> </dd></dl> <dl class="function"> <dt id="csv.get_dialect"> <code class="descclassname">csv.</code><code class="descname">get_dialect</code><span class="sig-paren">(</span><em>name</em><span class="sig-paren">)</span><a class="headerlink" href="#csv.get_dialect" title="本定義的永久連結">¶</a></dt> <dd><p>Return the dialect associated with <em>name</em>. An <a class="reference internal" href="#csv.Error" title="csv.Error"><code class="xref py py-exc docutils literal notranslate"><span class="pre">Error</span></code></a> is raised if <em>name</em> is not a registered dialect name. This function returns an immutable <a class="reference internal" href="#csv.Dialect" title="csv.Dialect"><code class="xref py py-class docutils literal notranslate"><span class="pre">Dialect</span></code></a>.</p> </dd></dl> <dl class="function"> <dt id="csv.list_dialects"> <code class="descclassname">csv.</code><code class="descname">list_dialects</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#csv.list_dialects" title="本定義的永久連結">¶</a></dt> <dd><p>Return the names of all registered dialects.</p> </dd></dl> <dl class="function"> <dt id="csv.field_size_limit"> <code class="descclassname">csv.</code><code class="descname">field_size_limit</code><span class="sig-paren">(</span><span class="optional">[</span><em>new_limit</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#csv.field_size_limit" title="本定義的永久連結">¶</a></dt> <dd><p>Returns the current maximum field size allowed by the parser. If <em>new_limit</em> is given, this becomes the new limit.</p> </dd></dl> <p>The <a class="reference internal" href="#module-csv" title="csv: Write and read tabular data to and from delimited files."><code class="xref py py-mod docutils literal notranslate"><span class="pre">csv</span></code></a> module defines the following classes:</p> <dl class="class"> <dt id="csv.DictReader"> <em class="property">class </em><code class="descclassname">csv.</code><code class="descname">DictReader</code><span class="sig-paren">(</span><em>f</em>, <em>fieldnames=None</em>, <em>restkey=None</em>, <em>restval=None</em>, <em>dialect='excel'</em>, <em>*args</em>, <em>**kwds</em><span class="sig-paren">)</span><a class="headerlink" href="#csv.DictReader" title="本定義的永久連結">¶</a></dt> <dd><p>Create an object that operates like a regular reader but maps the information in each row to an <a class="reference internal" href="collections.html#collections.OrderedDict" title="collections.OrderedDict"><code class="xref py py-mod docutils literal notranslate"><span class="pre">OrderedDict</span></code></a> whose keys are given by the optional <em>fieldnames</em> parameter.</p> <p>The <em>fieldnames</em> parameter is a <a class="reference internal" href="../glossary.html#term-sequence"><span class="xref std std-term">sequence</span></a>. If <em>fieldnames</em> is omitted, the values in the first row of file <em>f</em> will be used as the fieldnames. Regardless of how the fieldnames are determined, the ordered dictionary preserves their original ordering.</p> <p>If a row has more fields than fieldnames, the remaining data is put in a list and stored with the fieldname specified by <em>restkey</em> (which defaults to <code class="docutils literal notranslate"><span class="pre">None</span></code>). If a non-blank row has fewer fields than fieldnames, the missing values are filled-in with <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p> <p>All other optional or keyword arguments are passed to the underlying <a class="reference internal" href="#csv.reader" title="csv.reader"><code class="xref py py-class docutils literal notranslate"><span class="pre">reader</span></code></a> instance.</p> <div class="versionchanged"> <p><span class="versionmodified">3.6 版更變: </span>Returned rows are now of type <code class="xref py py-class docutils literal notranslate"><span class="pre">OrderedDict</span></code>.</p> </div> <p>A short usage example:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">csv</span> <span class="gp">>>> </span><span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">'names.csv'</span><span class="p">,</span> <span class="n">newline</span><span class="o">=</span><span class="s1">''</span><span class="p">)</span> <span class="k">as</span> <span class="n">csvfile</span><span class="p">:</span> <span class="gp">... </span> <span class="n">reader</span> <span class="o">=</span> <span class="n">csv</span><span class="o">.</span><span class="n">DictReader</span><span class="p">(</span><span class="n">csvfile</span><span class="p">)</span> <span class="gp">... </span> <span class="k">for</span> <span class="n">row</span> <span class="ow">in</span> <span class="n">reader</span><span class="p">:</span> <span class="gp">... </span> <span class="nb">print</span><span class="p">(</span><span class="n">row</span><span class="p">[</span><span class="s1">'first_name'</span><span class="p">],</span> <span class="n">row</span><span class="p">[</span><span class="s1">'last_name'</span><span class="p">])</span> <span class="gp">...</span> <span class="go">Eric Idle</span> <span class="go">John Cleese</span> <span class="gp">>>> </span><span class="nb">print</span><span class="p">(</span><span class="n">row</span><span class="p">)</span> <span class="go">OrderedDict([('first_name', 'John'), ('last_name', 'Cleese')])</span> </pre></div> </div> </dd></dl> <dl class="class"> <dt id="csv.DictWriter"> <em class="property">class </em><code class="descclassname">csv.</code><code class="descname">DictWriter</code><span class="sig-paren">(</span><em>f</em>, <em>fieldnames</em>, <em>restval=''</em>, <em>extrasaction='raise'</em>, <em>dialect='excel'</em>, <em>*args</em>, <em>**kwds</em><span class="sig-paren">)</span><a class="headerlink" href="#csv.DictWriter" title="本定義的永久連結">¶</a></dt> <dd><p>Create an object which operates like a regular writer but maps dictionaries onto output rows. The <em>fieldnames</em> parameter is a <a class="reference internal" href="collections.abc.html#module-collections.abc" title="collections.abc: Abstract base classes for containers"><code class="xref py py-mod docutils literal notranslate"><span class="pre">sequence</span></code></a> of keys that identify the order in which values in the dictionary passed to the <code class="xref py py-meth docutils literal notranslate"><span class="pre">writerow()</span></code> method are written to file <em>f</em>. The optional <em>restval</em> parameter specifies the value to be written if the dictionary is missing a key in <em>fieldnames</em>. If the dictionary passed to the <code class="xref py py-meth docutils literal notranslate"><span class="pre">writerow()</span></code> method contains a key not found in <em>fieldnames</em>, the optional <em>extrasaction</em> parameter indicates what action to take. If it is set to <code class="docutils literal notranslate"><span class="pre">'raise'</span></code>, the default value, a <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> is raised. If it is set to <code class="docutils literal notranslate"><span class="pre">'ignore'</span></code>, extra values in the dictionary are ignored. Any other optional or keyword arguments are passed to the underlying <a class="reference internal" href="#csv.writer" title="csv.writer"><code class="xref py py-class docutils literal notranslate"><span class="pre">writer</span></code></a> instance.</p> <p>Note that unlike the <a class="reference internal" href="#csv.DictReader" title="csv.DictReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">DictReader</span></code></a> class, the <em>fieldnames</em> parameter of the <a class="reference internal" href="#csv.DictWriter" title="csv.DictWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">DictWriter</span></code></a> class is not optional.</p> <p>A short usage example:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">csv</span> <span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">'names.csv'</span><span class="p">,</span> <span class="s1">'w'</span><span class="p">,</span> <span class="n">newline</span><span class="o">=</span><span class="s1">''</span><span class="p">)</span> <span class="k">as</span> <span class="n">csvfile</span><span class="p">:</span> <span class="n">fieldnames</span> <span class="o">=</span> <span class="p">[</span><span class="s1">'first_name'</span><span class="p">,</span> <span class="s1">'last_name'</span><span class="p">]</span> <span class="n">writer</span> <span class="o">=</span> <span class="n">csv</span><span class="o">.</span><span class="n">DictWriter</span><span class="p">(</span><span class="n">csvfile</span><span class="p">,</span> <span class="n">fieldnames</span><span class="o">=</span><span class="n">fieldnames</span><span class="p">)</span> <span class="n">writer</span><span class="o">.</span><span class="n">writeheader</span><span class="p">()</span> <span class="n">writer</span><span class="o">.</span><span class="n">writerow</span><span class="p">({</span><span class="s1">'first_name'</span><span class="p">:</span> <span class="s1">'Baked'</span><span class="p">,</span> <span class="s1">'last_name'</span><span class="p">:</span> <span class="s1">'Beans'</span><span class="p">})</span> <span class="n">writer</span><span class="o">.</span><span class="n">writerow</span><span class="p">({</span><span class="s1">'first_name'</span><span class="p">:</span> <span class="s1">'Lovely'</span><span class="p">,</span> <span class="s1">'last_name'</span><span class="p">:</span> <span class="s1">'Spam'</span><span class="p">})</span> <span class="n">writer</span><span class="o">.</span><span class="n">writerow</span><span class="p">({</span><span class="s1">'first_name'</span><span class="p">:</span> <span class="s1">'Wonderful'</span><span class="p">,</span> <span class="s1">'last_name'</span><span class="p">:</span> <span class="s1">'Spam'</span><span class="p">})</span> </pre></div> </div> </dd></dl> <dl class="class"> <dt id="csv.Dialect"> <em class="property">class </em><code class="descclassname">csv.</code><code class="descname">Dialect</code><a class="headerlink" href="#csv.Dialect" title="本定義的永久連結">¶</a></dt> <dd><p>The <a class="reference internal" href="#csv.Dialect" title="csv.Dialect"><code class="xref py py-class docutils literal notranslate"><span class="pre">Dialect</span></code></a> class is a container class relied on primarily for its attributes, which are used to define the parameters for a specific <a class="reference internal" href="#csv.reader" title="csv.reader"><code class="xref py py-class docutils literal notranslate"><span class="pre">reader</span></code></a> or <a class="reference internal" href="#csv.writer" title="csv.writer"><code class="xref py py-class docutils literal notranslate"><span class="pre">writer</span></code></a> instance.</p> </dd></dl> <dl class="class"> <dt id="csv.excel"> <em class="property">class </em><code class="descclassname">csv.</code><code class="descname">excel</code><a class="headerlink" href="#csv.excel" title="本定義的永久連結">¶</a></dt> <dd><p>The <a class="reference internal" href="#csv.excel" title="csv.excel"><code class="xref py py-class docutils literal notranslate"><span class="pre">excel</span></code></a> class defines the usual properties of an Excel-generated CSV file. It is registered with the dialect name <code class="docutils literal notranslate"><span class="pre">'excel'</span></code>.</p> </dd></dl> <dl class="class"> <dt id="csv.excel_tab"> <em class="property">class </em><code class="descclassname">csv.</code><code class="descname">excel_tab</code><a class="headerlink" href="#csv.excel_tab" title="本定義的永久連結">¶</a></dt> <dd><p>The <a class="reference internal" href="#csv.excel_tab" title="csv.excel_tab"><code class="xref py py-class docutils literal notranslate"><span class="pre">excel_tab</span></code></a> class defines the usual properties of an Excel-generated TAB-delimited file. It is registered with the dialect name <code class="docutils literal notranslate"><span class="pre">'excel-tab'</span></code>.</p> </dd></dl> <dl class="class"> <dt id="csv.unix_dialect"> <em class="property">class </em><code class="descclassname">csv.</code><code class="descname">unix_dialect</code><a class="headerlink" href="#csv.unix_dialect" title="本定義的永久連結">¶</a></dt> <dd><p>The <a class="reference internal" href="#csv.unix_dialect" title="csv.unix_dialect"><code class="xref py py-class docutils literal notranslate"><span class="pre">unix_dialect</span></code></a> class defines the usual properties of a CSV file generated on UNIX systems, i.e. using <code class="docutils literal notranslate"><span class="pre">'\n'</span></code> as line terminator and quoting all fields. It is registered with the dialect name <code class="docutils literal notranslate"><span class="pre">'unix'</span></code>.</p> <div class="versionadded"> <p><span class="versionmodified">3.2 版新加入.</span></p> </div> </dd></dl> <dl class="class"> <dt id="csv.Sniffer"> <em class="property">class </em><code class="descclassname">csv.</code><code class="descname">Sniffer</code><a class="headerlink" href="#csv.Sniffer" title="本定義的永久連結">¶</a></dt> <dd><p>The <a class="reference internal" href="#csv.Sniffer" title="csv.Sniffer"><code class="xref py py-class docutils literal notranslate"><span class="pre">Sniffer</span></code></a> class is used to deduce the format of a CSV file.</p> <p>The <a class="reference internal" href="#csv.Sniffer" title="csv.Sniffer"><code class="xref py py-class docutils literal notranslate"><span class="pre">Sniffer</span></code></a> class provides two methods:</p> <dl class="method"> <dt id="csv.Sniffer.sniff"> <code class="descname">sniff</code><span class="sig-paren">(</span><em>sample</em>, <em>delimiters=None</em><span class="sig-paren">)</span><a class="headerlink" href="#csv.Sniffer.sniff" title="本定義的永久連結">¶</a></dt> <dd><p>Analyze the given <em>sample</em> and return a <a class="reference internal" href="#csv.Dialect" title="csv.Dialect"><code class="xref py py-class docutils literal notranslate"><span class="pre">Dialect</span></code></a> subclass reflecting the parameters found. If the optional <em>delimiters</em> parameter is given, it is interpreted as a string containing possible valid delimiter characters.</p> </dd></dl> <dl class="method"> <dt id="csv.Sniffer.has_header"> <code class="descname">has_header</code><span class="sig-paren">(</span><em>sample</em><span class="sig-paren">)</span><a class="headerlink" href="#csv.Sniffer.has_header" title="本定義的永久連結">¶</a></dt> <dd><p>Analyze the sample text (presumed to be in CSV format) and return <a class="reference internal" href="constants.html#True" title="True"><code class="xref py py-const docutils literal notranslate"><span class="pre">True</span></code></a> if the first row appears to be a series of column headers.</p> </dd></dl> </dd></dl> <p>An example for <a class="reference internal" href="#csv.Sniffer" title="csv.Sniffer"><code class="xref py py-class docutils literal notranslate"><span class="pre">Sniffer</span></code></a> use:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">'example.csv'</span><span class="p">,</span> <span class="n">newline</span><span class="o">=</span><span class="s1">''</span><span class="p">)</span> <span class="k">as</span> <span class="n">csvfile</span><span class="p">:</span> <span class="n">dialect</span> <span class="o">=</span> <span class="n">csv</span><span class="o">.</span><span class="n">Sniffer</span><span class="p">()</span><span class="o">.</span><span class="n">sniff</span><span class="p">(</span><span class="n">csvfile</span><span class="o">.</span><span class="n">read</span><span class="p">(</span><span class="mi">1024</span><span class="p">))</span> <span class="n">csvfile</span><span class="o">.</span><span class="n">seek</span><span class="p">(</span><span class="mi">0</span><span class="p">)</span> <span class="n">reader</span> <span class="o">=</span> <span class="n">csv</span><span class="o">.</span><span class="n">reader</span><span class="p">(</span><span class="n">csvfile</span><span class="p">,</span> <span class="n">dialect</span><span class="p">)</span> <span class="c1"># ... process CSV file contents here ...</span> </pre></div> </div> <p>The <a class="reference internal" href="#module-csv" title="csv: Write and read tabular data to and from delimited files."><code class="xref py py-mod docutils literal notranslate"><span class="pre">csv</span></code></a> module defines the following constants:</p> <dl class="data"> <dt id="csv.QUOTE_ALL"> <code class="descclassname">csv.</code><code class="descname">QUOTE_ALL</code><a class="headerlink" href="#csv.QUOTE_ALL" title="本定義的永久連結">¶</a></dt> <dd><p>Instructs <a class="reference internal" href="#csv.writer" title="csv.writer"><code class="xref py py-class docutils literal notranslate"><span class="pre">writer</span></code></a> objects to quote all fields.</p> </dd></dl> <dl class="data"> <dt id="csv.QUOTE_MINIMAL"> <code class="descclassname">csv.</code><code class="descname">QUOTE_MINIMAL</code><a class="headerlink" href="#csv.QUOTE_MINIMAL" title="本定義的永久連結">¶</a></dt> <dd><p>Instructs <a class="reference internal" href="#csv.writer" title="csv.writer"><code class="xref py py-class docutils literal notranslate"><span class="pre">writer</span></code></a> objects to only quote those fields which contain special characters such as <em>delimiter</em>, <em>quotechar</em> or any of the characters in <em>lineterminator</em>.</p> </dd></dl> <dl class="data"> <dt id="csv.QUOTE_NONNUMERIC"> <code class="descclassname">csv.</code><code class="descname">QUOTE_NONNUMERIC</code><a class="headerlink" href="#csv.QUOTE_NONNUMERIC" title="本定義的永久連結">¶</a></dt> <dd><p>Instructs <a class="reference internal" href="#csv.writer" title="csv.writer"><code class="xref py py-class docutils literal notranslate"><span class="pre">writer</span></code></a> objects to quote all non-numeric fields.</p> <p>Instructs the reader to convert all non-quoted fields to type <em>float</em>.</p> </dd></dl> <dl class="data"> <dt id="csv.QUOTE_NONE"> <code class="descclassname">csv.</code><code class="descname">QUOTE_NONE</code><a class="headerlink" href="#csv.QUOTE_NONE" title="本定義的永久連結">¶</a></dt> <dd><p>Instructs <a class="reference internal" href="#csv.writer" title="csv.writer"><code class="xref py py-class docutils literal notranslate"><span class="pre">writer</span></code></a> objects to never quote fields. When the current <em>delimiter</em> occurs in output data it is preceded by the current <em>escapechar</em> character. If <em>escapechar</em> is not set, the writer will raise <a class="reference internal" href="#csv.Error" title="csv.Error"><code class="xref py py-exc docutils literal notranslate"><span class="pre">Error</span></code></a> if any characters that require escaping are encountered.</p> <p>Instructs <a class="reference internal" href="#csv.reader" title="csv.reader"><code class="xref py py-class docutils literal notranslate"><span class="pre">reader</span></code></a> to perform no special processing of quote characters.</p> </dd></dl> <p>The <a class="reference internal" href="#module-csv" title="csv: Write and read tabular data to and from delimited files."><code class="xref py py-mod docutils literal notranslate"><span class="pre">csv</span></code></a> module defines the following exception:</p> <dl class="exception"> <dt id="csv.Error"> <em class="property">exception </em><code class="descclassname">csv.</code><code class="descname">Error</code><a class="headerlink" href="#csv.Error" title="本定義的永久連結">¶</a></dt> <dd><p>Raised by any of the functions when an error is detected.</p> </dd></dl> </div> <div class="section" id="dialects-and-formatting-parameters"> <span id="csv-fmt-params"></span><h2>14.1.2. Dialects and Formatting Parameters<a class="headerlink" href="#dialects-and-formatting-parameters" title="本標題的永久連結">¶</a></h2> <p>To make it easier to specify the format of input and output records, specific formatting parameters are grouped together into dialects. A dialect is a subclass of the <a class="reference internal" href="#csv.Dialect" title="csv.Dialect"><code class="xref py py-class docutils literal notranslate"><span class="pre">Dialect</span></code></a> class having a set of specific methods and a single <code class="xref py py-meth docutils literal notranslate"><span class="pre">validate()</span></code> method. When creating <a class="reference internal" href="#csv.reader" title="csv.reader"><code class="xref py py-class docutils literal notranslate"><span class="pre">reader</span></code></a> or <a class="reference internal" href="#csv.writer" title="csv.writer"><code class="xref py py-class docutils literal notranslate"><span class="pre">writer</span></code></a> objects, the programmer can specify a string or a subclass of the <a class="reference internal" href="#csv.Dialect" title="csv.Dialect"><code class="xref py py-class docutils literal notranslate"><span class="pre">Dialect</span></code></a> class as the dialect parameter. In addition to, or instead of, the <em>dialect</em> parameter, the programmer can also specify individual formatting parameters, which have the same names as the attributes defined below for the <a class="reference internal" href="#csv.Dialect" title="csv.Dialect"><code class="xref py py-class docutils literal notranslate"><span class="pre">Dialect</span></code></a> class.</p> <p>Dialects support the following attributes:</p> <dl class="attribute"> <dt id="csv.Dialect.delimiter"> <code class="descclassname">Dialect.</code><code class="descname">delimiter</code><a class="headerlink" href="#csv.Dialect.delimiter" title="本定義的永久連結">¶</a></dt> <dd><p>A one-character string used to separate fields. It defaults to <code class="docutils literal notranslate"><span class="pre">','</span></code>.</p> </dd></dl> <dl class="attribute"> <dt id="csv.Dialect.doublequote"> <code class="descclassname">Dialect.</code><code class="descname">doublequote</code><a class="headerlink" href="#csv.Dialect.doublequote" title="本定義的永久連結">¶</a></dt> <dd><p>Controls how instances of <em>quotechar</em> appearing inside a field should themselves be quoted. When <a class="reference internal" href="constants.html#True" title="True"><code class="xref py py-const docutils literal notranslate"><span class="pre">True</span></code></a>, the character is doubled. When <a class="reference internal" href="constants.html#False" title="False"><code class="xref py py-const docutils literal notranslate"><span class="pre">False</span></code></a>, the <em>escapechar</em> is used as a prefix to the <em>quotechar</em>. It defaults to <a class="reference internal" href="constants.html#True" title="True"><code class="xref py py-const docutils literal notranslate"><span class="pre">True</span></code></a>.</p> <p>On output, if <em>doublequote</em> is <a class="reference internal" href="constants.html#False" title="False"><code class="xref py py-const docutils literal notranslate"><span class="pre">False</span></code></a> and no <em>escapechar</em> is set, <a class="reference internal" href="#csv.Error" title="csv.Error"><code class="xref py py-exc docutils literal notranslate"><span class="pre">Error</span></code></a> is raised if a <em>quotechar</em> is found in a field.</p> </dd></dl> <dl class="attribute"> <dt id="csv.Dialect.escapechar"> <code class="descclassname">Dialect.</code><code class="descname">escapechar</code><a class="headerlink" href="#csv.Dialect.escapechar" title="本定義的永久連結">¶</a></dt> <dd><p>A one-character string used by the writer to escape the <em>delimiter</em> if <em>quoting</em> is set to <a class="reference internal" href="#csv.QUOTE_NONE" title="csv.QUOTE_NONE"><code class="xref py py-const docutils literal notranslate"><span class="pre">QUOTE_NONE</span></code></a> and the <em>quotechar</em> if <em>doublequote</em> is <a class="reference internal" href="constants.html#False" title="False"><code class="xref py py-const docutils literal notranslate"><span class="pre">False</span></code></a>. On reading, the <em>escapechar</em> removes any special meaning from the following character. It defaults to <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate"><span class="pre">None</span></code></a>, which disables escaping.</p> </dd></dl> <dl class="attribute"> <dt id="csv.Dialect.lineterminator"> <code class="descclassname">Dialect.</code><code class="descname">lineterminator</code><a class="headerlink" href="#csv.Dialect.lineterminator" title="本定義的永久連結">¶</a></dt> <dd><p>The string used to terminate lines produced by the <a class="reference internal" href="#csv.writer" title="csv.writer"><code class="xref py py-class docutils literal notranslate"><span class="pre">writer</span></code></a>. It defaults to <code class="docutils literal notranslate"><span class="pre">'\r\n'</span></code>.</p> <div class="admonition note"> <p class="first admonition-title">備註</p> <p class="last">The <a class="reference internal" href="#csv.reader" title="csv.reader"><code class="xref py py-class docutils literal notranslate"><span class="pre">reader</span></code></a> is hard-coded to recognise either <code class="docutils literal notranslate"><span class="pre">'\r'</span></code> or <code class="docutils literal notranslate"><span class="pre">'\n'</span></code> as end-of-line, and ignores <em>lineterminator</em>. This behavior may change in the future.</p> </div> </dd></dl> <dl class="attribute"> <dt id="csv.Dialect.quotechar"> <code class="descclassname">Dialect.</code><code class="descname">quotechar</code><a class="headerlink" href="#csv.Dialect.quotechar" title="本定義的永久連結">¶</a></dt> <dd><p>A one-character string used to quote fields containing special characters, such as the <em>delimiter</em> or <em>quotechar</em>, or which contain new-line characters. It defaults to <code class="docutils literal notranslate"><span class="pre">'"'</span></code>.</p> </dd></dl> <dl class="attribute"> <dt id="csv.Dialect.quoting"> <code class="descclassname">Dialect.</code><code class="descname">quoting</code><a class="headerlink" href="#csv.Dialect.quoting" title="本定義的永久連結">¶</a></dt> <dd><p>Controls when quotes should be generated by the writer and recognised by the reader. It can take on any of the <code class="xref py py-const docutils literal notranslate"><span class="pre">QUOTE_*</span></code> constants (see section <a class="reference internal" href="#csv-contents"><span class="std std-ref">Module Contents</span></a>) and defaults to <a class="reference internal" href="#csv.QUOTE_MINIMAL" title="csv.QUOTE_MINIMAL"><code class="xref py py-const docutils literal notranslate"><span class="pre">QUOTE_MINIMAL</span></code></a>.</p> </dd></dl> <dl class="attribute"> <dt id="csv.Dialect.skipinitialspace"> <code class="descclassname">Dialect.</code><code class="descname">skipinitialspace</code><a class="headerlink" href="#csv.Dialect.skipinitialspace" title="本定義的永久連結">¶</a></dt> <dd><p>When <a class="reference internal" href="constants.html#True" title="True"><code class="xref py py-const docutils literal notranslate"><span class="pre">True</span></code></a>, whitespace immediately following the <em>delimiter</em> is ignored. The default is <a class="reference internal" href="constants.html#False" title="False"><code class="xref py py-const docutils literal notranslate"><span class="pre">False</span></code></a>.</p> </dd></dl> <dl class="attribute"> <dt id="csv.Dialect.strict"> <code class="descclassname">Dialect.</code><code class="descname">strict</code><a class="headerlink" href="#csv.Dialect.strict" title="本定義的永久連結">¶</a></dt> <dd><p>When <code class="docutils literal notranslate"><span class="pre">True</span></code>, raise exception <a class="reference internal" href="#csv.Error" title="csv.Error"><code class="xref py py-exc docutils literal notranslate"><span class="pre">Error</span></code></a> on bad CSV input. The default is <code class="docutils literal notranslate"><span class="pre">False</span></code>.</p> </dd></dl> </div> <div class="section" id="reader-objects"> <h2>14.1.3. Reader Objects<a class="headerlink" href="#reader-objects" title="本標題的永久連結">¶</a></h2> <p>Reader objects (<a class="reference internal" href="#csv.DictReader" title="csv.DictReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">DictReader</span></code></a> instances and objects returned by the <a class="reference internal" href="#csv.reader" title="csv.reader"><code class="xref py py-func docutils literal notranslate"><span class="pre">reader()</span></code></a> function) have the following public methods:</p> <dl class="method"> <dt id="csv.csvreader.__next__"> <code class="descclassname">csvreader.</code><code class="descname">__next__</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#csv.csvreader.__next__" title="本定義的永久連結">¶</a></dt> <dd><p>Return the next row of the reader’s iterable object as a list (if the object was returned from <a class="reference internal" href="#csv.reader" title="csv.reader"><code class="xref py py-func docutils literal notranslate"><span class="pre">reader()</span></code></a>) or a dict (if it is a <a class="reference internal" href="#csv.DictReader" title="csv.DictReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">DictReader</span></code></a> instance), parsed according to the current dialect. Usually you should call this as <code class="docutils literal notranslate"><span class="pre">next(reader)</span></code>.</p> </dd></dl> <p>Reader objects have the following public attributes:</p> <dl class="attribute"> <dt id="csv.csvreader.dialect"> <code class="descclassname">csvreader.</code><code class="descname">dialect</code><a class="headerlink" href="#csv.csvreader.dialect" title="本定義的永久連結">¶</a></dt> <dd><p>A read-only description of the dialect in use by the parser.</p> </dd></dl> <dl class="attribute"> <dt id="csv.csvreader.line_num"> <code class="descclassname">csvreader.</code><code class="descname">line_num</code><a class="headerlink" href="#csv.csvreader.line_num" title="本定義的永久連結">¶</a></dt> <dd><p>The number of lines read from the source iterator. This is not the same as the number of records returned, as records can span multiple lines.</p> </dd></dl> <p>DictReader objects have the following public attribute:</p> <dl class="attribute"> <dt id="csv.csvreader.fieldnames"> <code class="descclassname">csvreader.</code><code class="descname">fieldnames</code><a class="headerlink" href="#csv.csvreader.fieldnames" title="本定義的永久連結">¶</a></dt> <dd><p>If not passed as a parameter when creating the object, this attribute is initialized upon first access or when the first record is read from the file.</p> </dd></dl> </div> <div class="section" id="writer-objects"> <h2>14.1.4. Writer Objects<a class="headerlink" href="#writer-objects" title="本標題的永久連結">¶</a></h2> <p><code class="xref py py-class docutils literal notranslate"><span class="pre">Writer</span></code> objects (<a class="reference internal" href="#csv.DictWriter" title="csv.DictWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">DictWriter</span></code></a> instances and objects returned by the <a class="reference internal" href="#csv.writer" title="csv.writer"><code class="xref py py-func docutils literal notranslate"><span class="pre">writer()</span></code></a> function) have the following public methods. A <em>row</em> must be an iterable of strings or numbers for <code class="xref py py-class docutils literal notranslate"><span class="pre">Writer</span></code> objects and a dictionary mapping fieldnames to strings or numbers (by passing them through <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-func docutils literal notranslate"><span class="pre">str()</span></code></a> first) for <a class="reference internal" href="#csv.DictWriter" title="csv.DictWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">DictWriter</span></code></a> objects. Note that complex numbers are written out surrounded by parens. This may cause some problems for other programs which read CSV files (assuming they support complex numbers at all).</p> <dl class="method"> <dt id="csv.csvwriter.writerow"> <code class="descclassname">csvwriter.</code><code class="descname">writerow</code><span class="sig-paren">(</span><em>row</em><span class="sig-paren">)</span><a class="headerlink" href="#csv.csvwriter.writerow" title="本定義的永久連結">¶</a></dt> <dd><p>Write the <em>row</em> parameter to the writer’s file object, formatted according to the current dialect.</p> <div class="versionchanged"> <p><span class="versionmodified">3.5 版更變: </span>Added support of arbitrary iterables.</p> </div> </dd></dl> <dl class="method"> <dt id="csv.csvwriter.writerows"> <code class="descclassname">csvwriter.</code><code class="descname">writerows</code><span class="sig-paren">(</span><em>rows</em><span class="sig-paren">)</span><a class="headerlink" href="#csv.csvwriter.writerows" title="本定義的永久連結">¶</a></dt> <dd><p>Write all elements in <em>rows</em> (an iterable of <em>row</em> objects as described above) to the writer’s file object, formatted according to the current dialect.</p> </dd></dl> <p>Writer objects have the following public attribute:</p> <dl class="attribute"> <dt id="csv.csvwriter.dialect"> <code class="descclassname">csvwriter.</code><code class="descname">dialect</code><a class="headerlink" href="#csv.csvwriter.dialect" title="本定義的永久連結">¶</a></dt> <dd><p>A read-only description of the dialect in use by the writer.</p> </dd></dl> <p>DictWriter objects have the following public method:</p> <dl class="method"> <dt id="csv.DictWriter.writeheader"> <code class="descclassname">DictWriter.</code><code class="descname">writeheader</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#csv.DictWriter.writeheader" title="本定義的永久連結">¶</a></dt> <dd><p>Write a row with the field names (as specified in the constructor).</p> <div class="versionadded"> <p><span class="versionmodified">3.2 版新加入.</span></p> </div> </dd></dl> </div> <div class="section" id="examples"> <span id="csv-examples"></span><h2>14.1.5. Examples<a class="headerlink" href="#examples" title="本標題的永久連結">¶</a></h2> <p>The simplest example of reading a CSV file:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">csv</span> <span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">'some.csv'</span><span class="p">,</span> <span class="n">newline</span><span class="o">=</span><span class="s1">''</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span> <span class="n">reader</span> <span class="o">=</span> <span class="n">csv</span><span class="o">.</span><span class="n">reader</span><span class="p">(</span><span class="n">f</span><span class="p">)</span> <span class="k">for</span> <span class="n">row</span> <span class="ow">in</span> <span class="n">reader</span><span class="p">:</span> <span class="nb">print</span><span class="p">(</span><span class="n">row</span><span class="p">)</span> </pre></div> </div> <p>Reading a file with an alternate format:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">csv</span> <span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">'passwd'</span><span class="p">,</span> <span class="n">newline</span><span class="o">=</span><span class="s1">''</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span> <span class="n">reader</span> <span class="o">=</span> <span class="n">csv</span><span class="o">.</span><span class="n">reader</span><span class="p">(</span><span class="n">f</span><span class="p">,</span> <span class="n">delimiter</span><span class="o">=</span><span class="s1">':'</span><span class="p">,</span> <span class="n">quoting</span><span class="o">=</span><span class="n">csv</span><span class="o">.</span><span class="n">QUOTE_NONE</span><span class="p">)</span> <span class="k">for</span> <span class="n">row</span> <span class="ow">in</span> <span class="n">reader</span><span class="p">:</span> <span class="nb">print</span><span class="p">(</span><span class="n">row</span><span class="p">)</span> </pre></div> </div> <p>The corresponding simplest possible writing example is:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">csv</span> <span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">'some.csv'</span><span class="p">,</span> <span class="s1">'w'</span><span class="p">,</span> <span class="n">newline</span><span class="o">=</span><span class="s1">''</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span> <span class="n">writer</span> <span class="o">=</span> <span class="n">csv</span><span class="o">.</span><span class="n">writer</span><span class="p">(</span><span class="n">f</span><span class="p">)</span> <span class="n">writer</span><span class="o">.</span><span class="n">writerows</span><span class="p">(</span><span class="n">someiterable</span><span class="p">)</span> </pre></div> </div> <p>Since <a class="reference internal" href="functions.html#open" title="open"><code class="xref py py-func docutils literal notranslate"><span class="pre">open()</span></code></a> is used to open a CSV file for reading, the file will by default be decoded into unicode using the system default encoding (see <a class="reference internal" href="locale.html#locale.getpreferredencoding" title="locale.getpreferredencoding"><code class="xref py py-func docutils literal notranslate"><span class="pre">locale.getpreferredencoding()</span></code></a>). To decode a file using a different encoding, use the <code class="docutils literal notranslate"><span class="pre">encoding</span></code> argument of open:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">csv</span> <span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">'some.csv'</span><span class="p">,</span> <span class="n">newline</span><span class="o">=</span><span class="s1">''</span><span class="p">,</span> <span class="n">encoding</span><span class="o">=</span><span class="s1">'utf-8'</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span> <span class="n">reader</span> <span class="o">=</span> <span class="n">csv</span><span class="o">.</span><span class="n">reader</span><span class="p">(</span><span class="n">f</span><span class="p">)</span> <span class="k">for</span> <span class="n">row</span> <span class="ow">in</span> <span class="n">reader</span><span class="p">:</span> <span class="nb">print</span><span class="p">(</span><span class="n">row</span><span class="p">)</span> </pre></div> </div> <p>The same applies to writing in something other than the system default encoding: specify the encoding argument when opening the output file.</p> <p>Registering a new dialect:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">csv</span> <span class="n">csv</span><span class="o">.</span><span class="n">register_dialect</span><span class="p">(</span><span class="s1">'unixpwd'</span><span class="p">,</span> <span class="n">delimiter</span><span class="o">=</span><span class="s1">':'</span><span class="p">,</span> <span class="n">quoting</span><span class="o">=</span><span class="n">csv</span><span class="o">.</span><span class="n">QUOTE_NONE</span><span class="p">)</span> <span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">'passwd'</span><span class="p">,</span> <span class="n">newline</span><span class="o">=</span><span class="s1">''</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span> <span class="n">reader</span> <span class="o">=</span> <span class="n">csv</span><span class="o">.</span><span class="n">reader</span><span class="p">(</span><span class="n">f</span><span class="p">,</span> <span class="s1">'unixpwd'</span><span class="p">)</span> </pre></div> </div> <p>A slightly more advanced use of the reader — catching and reporting errors:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">csv</span><span class="o">,</span> <span class="nn">sys</span> <span class="n">filename</span> <span class="o">=</span> <span class="s1">'some.csv'</span> <span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="n">filename</span><span class="p">,</span> <span class="n">newline</span><span class="o">=</span><span class="s1">''</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span> <span class="n">reader</span> <span class="o">=</span> <span class="n">csv</span><span class="o">.</span><span class="n">reader</span><span class="p">(</span><span class="n">f</span><span class="p">)</span> <span class="k">try</span><span class="p">:</span> <span class="k">for</span> <span class="n">row</span> <span class="ow">in</span> <span class="n">reader</span><span class="p">:</span> <span class="nb">print</span><span class="p">(</span><span class="n">row</span><span class="p">)</span> <span class="k">except</span> <span class="n">csv</span><span class="o">.</span><span class="n">Error</span> <span class="k">as</span> <span class="n">e</span><span class="p">:</span> <span class="n">sys</span><span class="o">.</span><span class="n">exit</span><span class="p">(</span><span class="s1">'file </span><span class="si">{}</span><span class="s1">, line </span><span class="si">{}</span><span class="s1">: </span><span class="si">{}</span><span class="s1">'</span><span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">filename</span><span class="p">,</span> <span class="n">reader</span><span class="o">.</span><span class="n">line_num</span><span class="p">,</span> <span class="n">e</span><span class="p">))</span> </pre></div> </div> <p>And while the module doesn’t directly support parsing strings, it can easily be done:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">csv</span> <span class="k">for</span> <span class="n">row</span> <span class="ow">in</span> <span class="n">csv</span><span class="o">.</span><span class="n">reader</span><span class="p">([</span><span class="s1">'one,two,three'</span><span class="p">]):</span> <span class="nb">print</span><span class="p">(</span><span class="n">row</span><span class="p">)</span> </pre></div> </div> <p class="rubric">註解</p> <table class="docutils footnote" frame="void" id="id3" rules="none"> <colgroup><col class="label" /><col /></colgroup> <tbody valign="top"> <tr><td class="label">[1]</td><td><em>(<a class="fn-backref" href="#id1">1</a>, <a class="fn-backref" href="#id2">2</a>)</em> If <code class="docutils literal notranslate"><span class="pre">newline=''</span></code> is not specified, newlines embedded inside quoted fields will not be interpreted correctly, and on platforms that use <code class="docutils literal notranslate"><span class="pre">\r\n</span></code> linendings on write an extra <code class="docutils literal notranslate"><span class="pre">\r</span></code> will be added. It should always be safe to specify <code class="docutils literal notranslate"><span class="pre">newline=''</span></code>, since the csv module does its own (<a class="reference internal" href="../glossary.html#term-universal-newlines"><span class="xref std std-term">universal</span></a>) newline handling.</td></tr> </tbody> </table> </div> </div> </div> </div> </div> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <h3><a href="../contents.html">目錄</a></h3> <ul> <li><a class="reference internal" href="#">14.1. <code class="docutils literal notranslate"><span class="pre">csv</span></code> — CSV File Reading and Writing</a><ul> <li><a class="reference internal" href="#module-contents">14.1.1. Module Contents</a></li> <li><a class="reference internal" href="#dialects-and-formatting-parameters">14.1.2. Dialects and Formatting Parameters</a></li> <li><a class="reference internal" href="#reader-objects">14.1.3. Reader Objects</a></li> <li><a class="reference internal" href="#writer-objects">14.1.4. Writer Objects</a></li> <li><a class="reference internal" href="#examples">14.1.5. Examples</a></li> </ul> </li> </ul> <h4>上個主題</h4> <p class="topless"><a href="fileformats.html" title="上一章">14. 檔案格式</a></p> <h4>下個主題</h4> <p class="topless"><a href="configparser.html" title="下一章">14.2. <code class="docutils literal notranslate"><span class="pre">configparser</span></code> — Configuration file parser</a></p> <div role="note" aria-label="source link"> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../bugs.html">Report a Bug</a></li> <li> <a href="https://github.com/python/cpython/blob/3.7/Doc/library/csv.rst" rel="nofollow">Show Source </a> </li> </ul> </div> </div> </div> <div class="clearer"></div> </div> <div class="related" role="navigation" aria-label="related navigation"> <h3>瀏覽</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" >索引</a></li> <li class="right" > <a href="../py-modindex.html" title="Python 模組索引" >模組</a> |</li> <li class="right" > <a href="configparser.html" title="14.2. configparser — Configuration file parser" >下一頁</a> |</li> <li class="right" > <a href="fileformats.html" title="14. 檔案格式" >上一頁</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <span class="language_switcher_placeholder">zh_TW</span> <span class="version_switcher_placeholder">3.7.0</span> <a href="../index.html">Documentation </a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >Python 標準函式庫 (Standard Library)</a> »</li> <li class="nav-item nav-item-2"><a href="fileformats.html" >14. 檔案格式</a> »</li> <li class="right"> <div class="inline-search" style="display: none" role="search"> <form class="inline-search" action="../search.html" method="get"> <input placeholder="Quick search" type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <script type="text/javascript">$('.inline-search').show(0);</script> | </li> </ul> </div> <div class="footer"> © <a href="../copyright.html">Copyright</a> 2001-2018, Python Software Foundation. <br /> The Python Software Foundation is a non-profit corporation. <a href="https://www.python.org/psf/donations/">Please donate.</a> <br /> Last updated on 8月 22, 2018. <a href="../bugs.html">Found a bug</a>? <br /> Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.7.7. </div> </body> </html> |
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