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<h3 id="csv-文件是什么">CSV 文件是什么<a aria-hidden="true" tabindex="-1" href="#csv-文件是什么" class="internal"> §</a></h3>
<p>CSVComma Separated Values字符分隔值是一种简单的文件格式用来存储表格数据如电子表格或数据库。CSV 文件由任意数量的记录组成,记录间以某种换行符分隔。每条记录由字段组成,字段间的分隔符是其他字符或字符串,最常见的是逗号或制表符。</p>
<h3 id="用途和优点">用途和优点<a aria-hidden="true" tabindex="-1" href="#用途和优点" class="internal"> §</a></h3>
<p>CSV 文件常用于数据的导入导出,可以被大多数类型的软件包括文本编辑器和电子表格程序读取。其优点包括<strong>简单、易于阅读、跨平台和语言兼容。</strong></p>
<h3 id="基本结构">基本结构<a aria-hidden="true" tabindex="-1" href="#基本结构" class="internal"> §</a></h3>
<p>CSV 文件由行和列组成。每一行代表一个数据记录,而列则代表该记录的字段。字段的值由逗号分隔,不同的行则由换行符分隔。</p>
<div data-rehype-pretty-code-fragment><pre style="background-color:var(--shiki-color-background);" tabindex="0" data-language="text" data-theme="default"><code data-language="text" data-theme="default"><span data-line><span style="color:var(--shiki-color-text);">name,age,job</span></span>
<span data-line><span style="color:var(--shiki-color-text);">John,25,Engineer</span></span>
<span data-line><span style="color:var(--shiki-color-text);">Alice,30,Doctor</span></span></code></pre></div>
<h2 id="python-csv-模块">Python Csv 模块<a aria-hidden="true" tabindex="-1" href="#python-csv-模块" class="internal"> §</a></h2>
<p>Python 的 <code>csv</code> 模块提供了一种方便的方式来操作 CSV 文件。它包括了用于读取和写入 CSV 数据的函数,以及用于处理 CSV 数据的类。</p>
<p>在 Python 中导入 <code>csv</code> 模块只需要简单的 <code>import</code> 语句:</p>
<div data-rehype-pretty-code-fragment><pre style="background-color:var(--shiki-color-background);" tabindex="0" data-language="python" data-theme="default"><code data-language="python" data-theme="default"><span data-line><span style="color:var(--shiki-token-keyword);">import</span><span style="color:var(--shiki-color-text);"> csv</span></span></code></pre></div>
<h3 id="主要函数和类">主要函数和类<a aria-hidden="true" tabindex="-1" href="#主要函数和类" class="internal"> §</a></h3>
<p><code>csv</code> 模块的主要函数和类有:</p>
<ul>
<li><code>csv.reader()</code>:生成一个读取器对象,用于迭代读取 CSV 文件的每一行。</li>
<li><code>csv.writer()</code>:生成一个写入器对象,用于将数据写入 CSV 文件。</li>
<li><code>csv.DictReader()</code>:生成一个读取器对象,用于以字典形式读取 CSV 文件的每一行。</li>
<li><code>csv.DictWriter()</code>:生成一个写入器对象,用于将字典数据写入 CSV 文件。</li>
</ul>
<h2 id="读取-csv-文件">读取 CSV 文件<a aria-hidden="true" tabindex="-1" href="#读取-csv-文件" class="internal"> §</a></h2>
<h3 id="使用-csvreader-函数读取-csv-文件">使用 csv.reader() 函数读取 CSV 文件<a aria-hidden="true" tabindex="-1" href="#使用-csvreader-函数读取-csv-文件" class="internal"> §</a></h3>
<p>使用 <code>csv.reader()</code> 函数读取 CSV 文件的步骤如下:</p>
<ol>
<li>打开你想要读取的 CSV 文件。</li>
<li>创建一个 <code>csv.reader</code> 对象,传入该文件对象作为参数。</li>
<li>迭代 <code>csv.reader</code> 对象,读取文件的每一行。</li>
</ol>
<div data-rehype-pretty-code-fragment><pre style="background-color:var(--shiki-color-background);" tabindex="0" data-language="python" data-theme="default"><code data-language="python" data-theme="default"><span data-line><span style="color:var(--shiki-token-keyword);">import</span><span style="color:var(--shiki-color-text);"> csv</span></span>
<span data-line> </span>
<span data-line><span style="color:var(--shiki-token-keyword);">with</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-function);">open</span><span style="color:var(--shiki-token-punctuation);">(</span><span style="color:var(--shiki-token-string-expression);">'example.csv'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'r'</span><span style="color:var(--shiki-token-punctuation);">)</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-keyword);">as</span><span style="color:var(--shiki-color-text);"> file</span><span style="color:var(--shiki-token-punctuation);">:</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> reader </span><span style="color:var(--shiki-token-keyword);">=</span><span style="color:var(--shiki-color-text);"> csv</span><span style="color:var(--shiki-token-punctuation);">.</span><span style="color:var(--shiki-token-function);">reader</span><span style="color:var(--shiki-token-punctuation);">(file)</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-keyword);">for</span><span style="color:var(--shiki-color-text);"> row </span><span style="color:var(--shiki-token-keyword);">in</span><span style="color:var(--shiki-color-text);"> reader</span><span style="color:var(--shiki-token-punctuation);">:</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-function);">print</span><span style="color:var(--shiki-token-punctuation);">(row)</span></span></code></pre></div>
<p>**读取 CSV 文件时可能遇到的问题包括编码问题、字段格式问题等。**常见解决方法包括指定文件的编码方式、使用 <code>try-except</code> 块处理可能出现的错误等。</p>
<h3 id="csv-文件的读取实例">CSV 文件的读取实例<a aria-hidden="true" tabindex="-1" href="#csv-文件的读取实例" class="internal"> §</a></h3>
<p>假设我们有一个名为 <code>employees.csv</code> 的 CSV 文件,内容如下:</p>
<div data-rehype-pretty-code-fragment><pre style="background-color:var(--shiki-color-background);" tabindex="0" data-language="plaintext" data-theme="default"><code data-language="plaintext" data-theme="default"><span data-line><span style="color:var(--shiki-color-text);">name,age,department</span></span>
<span data-line><span style="color:var(--shiki-color-text);">John Doe,30,Engineering</span></span>
<span data-line><span style="color:var(--shiki-color-text);">Jane Smith,40,Marketing</span></span></code></pre></div>
<p>我们可以使用以下代码来读取这个文件:</p>
<div data-rehype-pretty-code-fragment><pre style="background-color:var(--shiki-color-background);" tabindex="0" data-language="python" data-theme="default"><code data-language="python" data-theme="default"><span data-line><span style="color:var(--shiki-token-keyword);">import</span><span style="color:var(--shiki-color-text);"> csv</span></span>
<span data-line> </span>
<span data-line><span style="color:var(--shiki-token-keyword);">with</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-function);">open</span><span style="color:var(--shiki-token-punctuation);">(</span><span style="color:var(--shiki-token-string-expression);">'employees.csv'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'r'</span><span style="color:var(--shiki-token-punctuation);">)</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-keyword);">as</span><span style="color:var(--shiki-color-text);"> file</span><span style="color:var(--shiki-token-punctuation);">:</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> reader </span><span style="color:var(--shiki-token-keyword);">=</span><span style="color:var(--shiki-color-text);"> csv</span><span style="color:var(--shiki-token-punctuation);">.</span><span style="color:var(--shiki-token-function);">reader</span><span style="color:var(--shiki-token-punctuation);">(file)</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-keyword);">for</span><span style="color:var(--shiki-color-text);"> row </span><span style="color:var(--shiki-token-keyword);">in</span><span style="color:var(--shiki-color-text);"> reader</span><span style="color:var(--shiki-token-punctuation);">:</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-function);">print</span><span style="color:var(--shiki-token-punctuation);">(</span><span style="color:var(--shiki-token-keyword);">f</span><span style="color:var(--shiki-token-string-expression);">'Name: </span><span style="color:var(--shiki-token-constant);">{</span><span style="color:var(--shiki-token-punctuation);">row[</span><span style="color:var(--shiki-token-constant);">0</span><span style="color:var(--shiki-token-punctuation);">]</span><span style="color:var(--shiki-token-constant);">}</span><span style="color:var(--shiki-token-string-expression);">, Age: </span><span style="color:var(--shiki-token-constant);">{</span><span style="color:var(--shiki-token-punctuation);">row[</span><span style="color:var(--shiki-token-constant);">1</span><span style="color:var(--shiki-token-punctuation);">]</span><span style="color:var(--shiki-token-constant);">}</span><span style="color:var(--shiki-token-string-expression);">, Department: </span><span style="color:var(--shiki-token-constant);">{</span><span style="color:var(--shiki-token-punctuation);">row[</span><span style="color:var(--shiki-token-constant);">2</span><span style="color:var(--shiki-token-punctuation);">]</span><span style="color:var(--shiki-token-constant);">}</span><span style="color:var(--shiki-token-string-expression);">'</span><span style="color:var(--shiki-token-punctuation);">)</span></span></code></pre></div>
<h2 id="写入-csv-文件">写入 CSV 文件<a aria-hidden="true" tabindex="-1" href="#写入-csv-文件" class="internal"> §</a></h2>
<h3 id="使用-csvwriter-函数写入-csv-文件">使用 csv.writer() 函数写入 CSV 文件<a aria-hidden="true" tabindex="-1" href="#使用-csvwriter-函数写入-csv-文件" class="internal"> §</a></h3>
<p>使用 <code>csv.writer()</code> 函数写入 CSV 文件的步骤如下:</p>
<ol>
<li>打开你想要写入的 CSV 文件。</li>
<li>创建一个 <code>csv.writer</code> 对象,传入该文件对象作为参数。</li>
<li>使用 <code>writerow()</code><code>writerows()</code> 方法,将数据写入文件。</li>
</ol>
<div data-rehype-pretty-code-fragment><pre style="background-color:var(--shiki-color-background);" tabindex="0" data-language="python" data-theme="default"><code data-language="python" data-theme="default"><span data-line><span style="color:var(--shiki-token-keyword);">import</span><span style="color:var(--shiki-color-text);"> csv</span></span>
<span data-line> </span>
<span data-line><span style="color:var(--shiki-token-keyword);">with</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-function);">open</span><span style="color:var(--shiki-token-punctuation);">(</span><span style="color:var(--shiki-token-string-expression);">'example.csv'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'w'</span><span style="color:var(--shiki-token-punctuation);">, newline</span><span style="color:var(--shiki-token-keyword);">=</span><span style="color:var(--shiki-token-string-expression);">''</span><span style="color:var(--shiki-token-punctuation);">)</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-keyword);">as</span><span style="color:var(--shiki-color-text);"> file</span><span style="color:var(--shiki-token-punctuation);">:</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> writer </span><span style="color:var(--shiki-token-keyword);">=</span><span style="color:var(--shiki-color-text);"> csv</span><span style="color:var(--shiki-token-punctuation);">.</span><span style="color:var(--shiki-token-function);">writer</span><span style="color:var(--shiki-token-punctuation);">(file)</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> writer</span><span style="color:var(--shiki-token-punctuation);">.</span><span style="color:var(--shiki-token-function);">writerow</span><span style="color:var(--shiki-token-punctuation);">([</span><span style="color:var(--shiki-token-string-expression);">'name'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'age'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'job'</span><span style="color:var(--shiki-token-punctuation);">])</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> writer</span><span style="color:var(--shiki-token-punctuation);">.</span><span style="color:var(--shiki-token-function);">writerow</span><span style="color:var(--shiki-token-punctuation);">([</span><span style="color:var(--shiki-token-string-expression);">'John'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'25'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'Engineer'</span><span style="color:var(--shiki-token-punctuation);">])</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> writer</span><span style="color:var(--shiki-token-punctuation);">.</span><span style="color:var(--shiki-token-function);">writerow</span><span style="color:var(--shiki-token-punctuation);">([</span><span style="color:var(--shiki-token-string-expression);">'Alice'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'30'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'Doctor'</span><span style="color:var(--shiki-token-punctuation);">])</span></span></code></pre></div>
<p>**写入 CSV 文件可能遇到的问题包括权限问题、磁盘空间问题等。**常见解决方法包括检查文件写入权限、确保磁盘有足够空间等。</p>
<h3 id="csv-文件的写入实例">CSV 文件的写入实例<a aria-hidden="true" tabindex="-1" href="#csv-文件的写入实例" class="internal"> §</a></h3>
<p>假设我们需要将以下数据写入一个名为 <code>employees.csv</code> 的 CSV 文件:</p>
<div data-rehype-pretty-code-fragment><pre style="background-color:var(--shiki-color-background);" tabindex="0" data-language="python" data-theme="default"><code data-language="python" data-theme="default"><span data-line><span style="color:var(--shiki-color-text);">employees </span><span style="color:var(--shiki-token-keyword);">=</span><span style="color:var(--shiki-color-text);"> [</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> [</span><span style="color:var(--shiki-token-string-expression);">'name'</span><span style="color:var(--shiki-token-punctuation);">,</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-string-expression);">'age'</span><span style="color:var(--shiki-token-punctuation);">,</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-string-expression);">'department'</span><span style="color:var(--shiki-color-text);">]</span><span style="color:var(--shiki-token-punctuation);">,</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> [</span><span style="color:var(--shiki-token-string-expression);">'John Doe'</span><span style="color:var(--shiki-token-punctuation);">,</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-string-expression);">'30'</span><span style="color:var(--shiki-token-punctuation);">,</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-string-expression);">'Engineering'</span><span style="color:var(--shiki-color-text);">]</span><span style="color:var(--shiki-token-punctuation);">,</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> [</span><span style="color:var(--shiki-token-string-expression);">'Jane Smith'</span><span style="color:var(--shiki-token-punctuation);">,</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-string-expression);">'40'</span><span style="color:var(--shiki-token-punctuation);">,</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-string-expression);">'Marketing'</span><span style="color:var(--shiki-color-text);">]</span></span>
<span data-line><span style="color:var(--shiki-color-text);">]</span></span></code></pre></div>
<p>我们可以使用以下代码来写入这个文件:</p>
<div data-rehype-pretty-code-fragment><pre style="background-color:var(--shiki-color-background);" tabindex="0" data-language="python" data-theme="default"><code data-language="python" data-theme="default"><span data-line><span style="color:var(--shiki-token-keyword);">import</span><span style="color:var(--shiki-color-text);"> csv</span></span>
<span data-line> </span>
<span data-line><span style="color:var(--shiki-token-keyword);">with</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-function);">open</span><span style="color:var(--shiki-token-punctuation);">(</span><span style="color:var(--shiki-token-string-expression);">'employees.csv'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'w'</span><span style="color:var(--shiki-token-punctuation);">, newline</span><span style="color:var(--shiki-token-keyword);">=</span><span style="color:var(--shiki-token-string-expression);">''</span><span style="color:var(--shiki-token-punctuation);">)</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-keyword);">as</span><span style="color:var(--shiki-color-text);"> file</span><span style="color:var(--shiki-token-punctuation);">:</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> writer </span><span style="color:var(--shiki-token-keyword);">=</span><span style="color:var(--shiki-color-text);"> csv</span><span style="color:var(--shiki-token-punctuation);">.</span><span style="color:var(--shiki-token-function);">writer</span><span style="color:var(--shiki-token-punctuation);">(file)</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> writer</span><span style="color:var(--shiki-token-punctuation);">.</span><span style="color:var(--shiki-token-function);">writerows</span><span style="color:var(--shiki-token-punctuation);">(employees)</span></span></code></pre></div>
<h2 id="csv-数据使用字典处理">CSV 数据使用字典处理<a aria-hidden="true" tabindex="-1" href="#csv-数据使用字典处理" class="internal"> §</a></h2>
<h3 id="使用-csvdictreader-函数读取-csv-文件并返回字典">使用 csv.DictReader() 函数读取 CSV 文件并返回字典<a aria-hidden="true" tabindex="-1" href="#使用-csvdictreader-函数读取-csv-文件并返回字典" class="internal"> §</a></h3>
<p><code>csv.DictReader()</code> 函数可以将 CSV 文件的每行读取为一个字典,其中列名为键,列值为值。</p>
<div data-rehype-pretty-code-fragment><pre style="background-color:var(--shiki-color-background);" tabindex="0" data-language="python" data-theme="default"><code data-language="python" data-theme="default"><span data-line><span style="color:var(--shiki-token-keyword);">import</span><span style="color:var(--shiki-color-text);"> csv</span></span>
<span data-line> </span>
<span data-line><span style="color:var(--shiki-token-keyword);">with</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-function);">open</span><span style="color:var(--shiki-token-punctuation);">(</span><span style="color:var(--shiki-token-string-expression);">'example.csv'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'r'</span><span style="color:var(--shiki-token-punctuation);">)</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-keyword);">as</span><span style="color:var(--shiki-color-text);"> file</span><span style="color:var(--shiki-token-punctuation);">:</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> reader </span><span style="color:var(--shiki-token-keyword);">=</span><span style="color:var(--shiki-color-text);"> csv</span><span style="color:var(--shiki-token-punctuation);">.</span><span style="color:var(--shiki-token-function);">DictReader</span><span style="color:var(--shiki-token-punctuation);">(file)</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-keyword);">for</span><span style="color:var(--shiki-color-text);"> row </span><span style="color:var(--shiki-token-keyword);">in</span><span style="color:var(--shiki-color-text);"> reader</span><span style="color:var(--shiki-token-punctuation);">:</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-function);">print</span><span style="color:var(--shiki-token-punctuation);">(row)</span></span></code></pre></div>
<h3 id="使用-csvdictwriter-函数将字典写入-csv-文件">使用 csv.DictWriter() 函数将字典写入 CSV 文件<a aria-hidden="true" tabindex="-1" href="#使用-csvdictwriter-函数将字典写入-csv-文件" class="internal"> §</a></h3>
<p><code>csv.DictWriter()</code> 函数可以将字典数据写入 CSV 文件。需要先指定列名,然后调用 <code>writeheader()</code> 方法写入列名,最后调用 <code>writerow()</code><code>writerows()</code> 方法写入字典数据。</p>
<div data-rehype-pretty-code-fragment><pre style="background-color:var(--shiki-color-background);" tabindex="0" data-language="python" data-theme="default"><code data-language="python" data-theme="default"><span data-line><span style="color:var(--shiki-token-keyword);">import</span><span style="color:var(--shiki-color-text);"> csv</span></span>
<span data-line> </span>
<span data-line><span style="color:var(--shiki-token-keyword);">with</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-function);">open</span><span style="color:var(--shiki-token-punctuation);">(</span><span style="color:var(--shiki-token-string-expression);">'example.csv'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'w'</span><span style="color:var(--shiki-token-punctuation);">, newline</span><span style="color:var(--shiki-token-keyword);">=</span><span style="color:var(--shiki-token-string-expression);">''</span><span style="color:var(--shiki-token-punctuation);">)</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-keyword);">as</span><span style="color:var(--shiki-color-text);"> file</span><span style="color:var(--shiki-token-punctuation);">:</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> fieldnames </span><span style="color:var(--shiki-token-keyword);">=</span><span style="color:var(--shiki-color-text);"> [</span><span style="color:var(--shiki-token-string-expression);">'name'</span><span style="color:var(--shiki-token-punctuation);">,</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-string-expression);">'age'</span><span style="color:var(--shiki-token-punctuation);">,</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-string-expression);">'job'</span><span style="color:var(--shiki-color-text);">]</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> writer </span><span style="color:var(--shiki-token-keyword);">=</span><span style="color:var(--shiki-color-text);"> csv</span><span style="color:var(--shiki-token-punctuation);">.</span><span style="color:var(--shiki-token-function);">DictWriter</span><span style="color:var(--shiki-token-punctuation);">(file, fieldnames</span><span style="color:var(--shiki-token-keyword);">=</span><span style="color:var(--shiki-token-punctuation);">fieldnames)</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> </span></span>
<span data-line><span style="color:var(--shiki-color-text);"> writer</span><span style="color:var(--shiki-token-punctuation);">.</span><span style="color:var(--shiki-token-function);">writeheader</span><span style="color:var(--shiki-token-punctuation);">()</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> writer</span><span style="color:var(--shiki-token-punctuation);">.</span><span style="color:var(--shiki-token-function);">writerow</span><span style="color:var(--shiki-token-punctuation);">({</span><span style="color:var(--shiki-token-string-expression);">'name'</span><span style="color:var(--shiki-token-punctuation);">: </span><span style="color:var(--shiki-token-string-expression);">'John'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'age'</span><span style="color:var(--shiki-token-punctuation);">: </span><span style="color:var(--shiki-token-string-expression);">'25'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'job'</span><span style="color:var(--shiki-token-punctuation);">: </span><span style="color:var(--shiki-token-string-expression);">'Engineer'</span><span style="color:var(--shiki-token-punctuation);">})</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> writer</span><span style="color:var(--shiki-token-punctuation);">.</span><span style="color:var(--shiki-token-function);">writerow</span><span style="color:var(--shiki-token-punctuation);">({</span><span style="color:var(--shiki-token-string-expression);">'name'</span><span style="color:var(--shiki-token-punctuation);">: </span><span style="color:var(--shiki-token-string-expression);">'Alice'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'age'</span><span style="color:var(--shiki-token-punctuation);">: </span><span style="color:var(--shiki-token-string-expression);">'30'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'job'</span><span style="color:var(--shiki-token-punctuation);">: </span><span style="color:var(--shiki-token-string-expression);">'Doctor'</span><span style="color:var(--shiki-token-punctuation);">})</span></span></code></pre></div>
<h3 id="字典和-csv-数据的交互">字典和 CSV 数据的交互<a aria-hidden="true" tabindex="-1" href="#字典和-csv-数据的交互" class="internal"> §</a></h3>
<p>假设我们有一个名为 <code>employees.csv</code> 的 CSV 文件,内容如下:</p>
<div data-rehype-pretty-code-fragment><pre style="background-color:var(--shiki-color-background);" tabindex="0" data-language="plaintext" data-theme="default"><code data-language="plaintext" data-theme="default"><span data-line><span style="color:var(--shiki-color-text);">name,age,department</span></span>
<span data-line><span style="color:var(--shiki-color-text);">John Doe,30,Engineering</span></span>
<span data-line><span style="color:var(--shiki-color-text);">Jane Smith,40,Marketing</span></span></code></pre></div>
<p>我们可以使用以下代码来读取这个文件,并打印出每个员工的名字和部门:</p>
<div data-rehype-pretty-code-fragment><pre style="background-color:var(--shiki-color-background);" tabindex="0" data-language="python" data-theme="default"><code data-language="python" data-theme="default"><span data-line><span style="color:var(--shiki-token-keyword);">import</span><span style="color:var(--shiki-color-text);"> csv</span></span>
<span data-line> </span>
<span data-line><span style="color:var(--shiki-token-keyword);">with</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-function);">open</span><span style="color:var(--shiki-token-punctuation);">(</span><span style="color:var(--shiki-token-string-expression);">'employees.csv'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'r'</span><span style="color:var(--shiki-token-punctuation);">)</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-keyword);">as</span><span style="color:var(--shiki-color-text);"> file</span><span style="color:var(--shiki-token-punctuation);">:</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> reader </span><span style="color:var(--shiki-token-keyword);">=</span><span style="color:var(--shiki-color-text);"> csv</span><span style="color:var(--shiki-token-punctuation);">.</span><span style="color:var(--shiki-token-function);">DictReader</span><span style="color:var(--shiki-token-punctuation);">(file)</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-keyword);">for</span><span style="color:var(--shiki-color-text);"> row </span><span style="color:var(--shiki-token-keyword);">in</span><span style="color:var(--shiki-color-text);"> reader</span><span style="color:var(--shiki-token-punctuation);">:</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-function);">print</span><span style="color:var(--shiki-token-punctuation);">(</span><span style="color:var(--shiki-token-keyword);">f</span><span style="color:var(--shiki-token-string-expression);">&quot;Name: </span><span style="color:var(--shiki-token-constant);">{</span><span style="color:var(--shiki-token-punctuation);">row[</span><span style="color:var(--shiki-token-string-expression);">'name'</span><span style="color:var(--shiki-token-punctuation);">]</span><span style="color:var(--shiki-token-constant);">}</span><span style="color:var(--shiki-token-string-expression);">, Department: </span><span style="color:var(--shiki-token-constant);">{</span><span style="color:var(--shiki-token-punctuation);">row[</span><span style="color:var(--shiki-token-string-expression);">'department'</span><span style="color:var(--shiki-token-punctuation);">]</span><span style="color:var(--shiki-token-constant);">}</span><span style="color:var(--shiki-token-string-expression);">&quot;</span><span style="color:var(--shiki-token-punctuation);">)</span></span></code></pre></div>
<h2 id="csv-文件中的错误和异常">CSV 文件中的错误和异常<a aria-hidden="true" tabindex="-1" href="#csv-文件中的错误和异常" class="internal"> §</a></h2>
<p>读取和写入 CSV 文件时可能遇到的错误和异常包括文件不存在、文件不可读写、磁盘空间不足等。可以使用 try-except 结构来捕获和处理这些异常。</p>
<div data-rehype-pretty-code-fragment><pre style="background-color:var(--shiki-color-background);" tabindex="0" data-language="python" data-theme="default"><code data-language="python" data-theme="default"><span data-line><span style="color:var(--shiki-token-keyword);">import</span><span style="color:var(--shiki-color-text);"> csv</span></span>
<span data-line> </span>
<span data-line><span style="color:var(--shiki-token-keyword);">try</span><span style="color:var(--shiki-token-punctuation);">:</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-keyword);">with</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-function);">open</span><span style="color:var(--shiki-token-punctuation);">(</span><span style="color:var(--shiki-token-string-expression);">'example.csv'</span><span style="color:var(--shiki-token-punctuation);">, </span><span style="color:var(--shiki-token-string-expression);">'r'</span><span style="color:var(--shiki-token-punctuation);">)</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-keyword);">as</span><span style="color:var(--shiki-color-text);"> file</span><span style="color:var(--shiki-token-punctuation);">:</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> reader </span><span style="color:var(--shiki-token-keyword);">=</span><span style="color:var(--shiki-color-text);"> csv</span><span style="color:var(--shiki-token-punctuation);">.</span><span style="color:var(--shiki-token-function);">reader</span><span style="color:var(--shiki-token-punctuation);">(file)</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-keyword);">for</span><span style="color:var(--shiki-color-text);"> row </span><span style="color:var(--shiki-token-keyword);">in</span><span style="color:var(--shiki-color-text);"> reader</span><span style="color:var(--shiki-token-punctuation);">:</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-function);">print</span><span style="color:var(--shiki-token-punctuation);">(row)</span></span>
<span data-line><span style="color:var(--shiki-token-keyword);">except</span><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-constant);">FileNotFoundError</span><span style="color:var(--shiki-token-punctuation);">:</span></span>
<span data-line><span style="color:var(--shiki-color-text);"> </span><span style="color:var(--shiki-token-function);">print</span><span style="color:var(--shiki-token-punctuation);">(</span><span style="color:var(--shiki-token-string-expression);">'File not found.'</span><span style="color:var(--shiki-token-punctuation);">)</span></span></code></pre></div>
<table><thead><tr><th align="left">错误类型</th><th align="left">错误描述</th><th align="left">解决方案</th></tr></thead><tbody><tr><td align="left"><code>FileNotFoundError</code></td><td align="left">找不到指定的文件。</td><td align="left">确保文件的路径和名称正确,且文件确实存在。</td></tr><tr><td align="left"><code>PermissionError</code></td><td align="left">没有足够的权限打开文件。</td><td align="left">确保你有足够的权限访问和修改文件。</td></tr><tr><td align="left"><code>IsADirectoryError</code></td><td align="left">尝试打开的是一个目录,而不是文件。</td><td align="left">确保指定的路径是文件,而非目录。</td></tr><tr><td align="left"><code>IOError</code></td><td align="left">文件读写出错,例如磁盘空间不足。</td><td align="left">确保磁盘有足够的空间,文件没有被其他程序锁定。</td></tr><tr><td align="left"><code>csv.Error</code></td><td align="left">CSV 文件格式错误。</td><td align="left">确保 CSV 文件的格式正确,例如字段是否正确分隔。</td></tr><tr><td align="left"><code>UnicodeDecodeError</code></td><td align="left">文件编码问题。</td><td align="left">确保文件的编码和你在 Python 中指定的编码一致。</td></tr></tbody></table></article></div><div class="right sidebar"><div class="graph "><h3>Graph View</h3><div class="graph-outer"><div id="graph-container" data-cfg="{&quot;drag&quot;:true,&quot;zoom&quot;:true,&quot;depth&quot;:1,&quot;scale&quot;:1.1,&quot;repelForce&quot;:0.5,&quot;centerForce&quot;:0.3,&quot;linkDistance&quot;:30,&quot;fontSize&quot;:0.6,&quot;opacityScale&quot;:1,&quot;showTags&quot;:true,&quot;removeTags&quot;:[]}"></div><svg version="1.1" id="global-graph-icon" xmlns="http://www.w3.org/2000/svg" xmlnsXlink="http://www.w3.org/1999/xlink" x="0px" y="0px" viewBox="0 0 55 55" fill="currentColor" xmlSpace="preserve"><path d="M49,0c-3.309,0-6,2.691-6,6c0,1.035,0.263,2.009,0.726,2.86l-9.829,9.829C32.542,17.634,30.846,17,29,17
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s-2-0.897-2-2s0.897-2,2-2S47,39.897,47,41z M49,10c-2.206,0-4-1.794-4-4s1.794-4,4-4s4,1.794,4,4S51.206,10,49,10z"></path></svg></div><div id="global-graph-outer"><div id="global-graph-container" data-cfg="{&quot;drag&quot;:true,&quot;zoom&quot;:true,&quot;depth&quot;:-1,&quot;scale&quot;:0.9,&quot;repelForce&quot;:0.5,&quot;centerForce&quot;:0.3,&quot;linkDistance&quot;:30,&quot;fontSize&quot;:0.6,&quot;opacityScale&quot;:1,&quot;showTags&quot;:true,&quot;removeTags&quot;:[]}"></div></div></div><div class="toc desktop-only"><button type="button" id="toc" class><h3>Table of Contents</h3><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="fold"><polyline points="6 9 12 15 18 9"></polyline></svg></button><div id="toc-content"><ul class="overflow"><li class="depth-0"><a href="#csv" data-for="csv">CSV</a></li><li class="depth-1"><a href="#csv-文件是什么" data-for="csv-文件是什么">CSV 文件是什么</a></li><li class="depth-1"><a href="#用途和优点" data-for="用途和优点">用途和优点</a></li><li class="depth-1"><a href="#基本结构" data-for="基本结构">基本结构</a></li><li class="depth-0"><a href="#python-csv-模块" data-for="python-csv-模块">Python Csv 模块</a></li><li class="depth-1"><a href="#主要函数和类" data-for="主要函数和类">主要函数和类</a></li><li class="depth-0"><a href="#读取-csv-文件" data-for="读取-csv-文件">读取 CSV 文件</a></li><li class="depth-1"><a href="#使用-csvreader-函数读取-csv-文件" data-for="使用-csvreader-函数读取-csv-文件">使用 csv.reader() 函数读取 CSV 文件</a></li><li class="depth-1"><a href="#csv-文件的读取实例" data-for="csv-文件的读取实例">CSV 文件的读取实例</a></li><li class="depth-0"><a href="#写入-csv-文件" data-for="写入-csv-文件">写入 CSV 文件</a></li><li class="depth-1"><a href="#使用-csvwriter-函数写入-csv-文件" data-for="使用-csvwriter-函数写入-csv-文件">使用 csv.writer() 函数写入 CSV 文件</a></li><li class="depth-1"><a href="#csv-文件的写入实例" data-for="csv-文件的写入实例">CSV 文件的写入实例</a></li><li class="depth-0"><a href="#csv-数据使用字典处理" data-for="csv-数据使用字典处理">CSV 数据使用字典处理</a></li><li class="depth-1"><a href="#使用-csvdictreader-函数读取-csv-文件并返回字典" data-for="使用-csvdictreader-函数读取-csv-文件并返回字典">使用 csv.DictReader() 函数读取 CSV 文件并返回字典</a></li><li class="depth-1"><a href="#使用-csvdictwriter-函数将字典写入-csv-文件" data-for="使用-csvdictwriter-函数将字典写入-csv-文件">使用 csv.DictWriter() 函数将字典写入 CSV 文件</a></li><li class="depth-1"><a href="#字典和-csv-数据的交互" data-for="字典和-csv-数据的交互">字典和 CSV 数据的交互</a></li><li class="depth-0"><a href="#csv-文件中的错误和异常" data-for="csv-文件中的错误和异常">CSV 文件中的错误和异常</a></li></ul></div></div><div class="backlinks "><h3>Backlinks</h3><ul class="overflow"><li><a href="../../../../../Tech/programming-language/Python/进阶/文件和IO操作" class="internal">文件和IO操作</a></li></ul></div><div class="explorer mobile-only"><button type="button" id="explorer" data-behavior="collapse" data-collapsed="collapsed" data-savestate="true" data-tree="[{&quot;path&quot;:&quot;Basics&quot;,&quot;collapsed&quot;:true},{&quot;path&quot;:&quot;Basics/english&quot;,&quot;collapsed&quot;:true},{&quot;path&quot;:&quot;Blog&quot;,&quot;collapsed&quot;:true},{&quot;path&quot;:&quot;Book&quot;,&quot;collapsed&quot;:true},{&quot;path&quot;:&quot;Book/个人成长&quot;,&quot;collapsed&quot;:true},{&quot;path&quot;:&quot;Book/医学健康&quot;,&quot;collapsed&quot;:true},{&quot;path&quot;:&quot;Book/历史&quot;,&quot;collapsed&quot;:true},{&quot;path&quot;:&quot;Book/哲学宗教&quot;,&quot;collapsed&quot;:true},{&quot;pa
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