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朱怪咖的野爹 發表於 2019-10-8 21:04:00

Python内置函数之enumerate() 函数

<p>enumerate() 函数属于python的内置函数之一；</p>
<p>python内置函数参考文档：python内置函数 </p>
<p>转载自enumerate参考文档：python-enumerate() 函数 </p>
<p> </p>
<h2>Python内置函数之enumerate() 函数</h2>
<h3>描述</h3>
<p>enumerate() 函数用于将一个可遍历的数据对象(如列表、元组或字符串)组合为一个索引序列，同时列出数据和数据下标，一般用在 for 循环当中。</p>
<p>Python 2.3. 以上版本可用，2.6 添加 start 参数。</p>
<p> </p>
<h3>语法</h3>
<p>以下是 enumerate() 方法的语法:</p>
<div class="cnblogs_code">
<pre>enumerate(sequence, )</pre>
</div>
<p> </p>
<h3>参数</h3>
<ul>
<li>sequence -- 一个序列、迭代器或其他支持迭代对象。</li>
<li>start -- 下标起始位置。</li>
</ul>
<p> </p>
<h3>返回值</h3>
<p>返回 enumerate(枚举) 对象。</p>
<p> </p>
<h3>实例</h3>
<p>以下展示了使用 enumerate() 方法的实例：</p>
<div class="cnblogs_code">
<pre>>>>seasons = [<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Spring</span><span style="color: rgba(128, 0, 0, 1)">'</span>, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Summer</span><span style="color: rgba(128, 0, 0, 1)">'</span>, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Fall</span><span style="color: rgba(128, 0, 0, 1)">'</span>, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Winter</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">]
</span>>>><span style="color: rgba(0, 0, 0, 1)"> list(enumerate(seasons))
[(0, </span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Spring</span><span style="color: rgba(128, 0, 0, 1)">'</span>), (1, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Summer</span><span style="color: rgba(128, 0, 0, 1)">'</span>), (2, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Fall</span><span style="color: rgba(128, 0, 0, 1)">'</span>), (3, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Winter</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">)]
</span>>>> list(enumerate(seasons, start=1)) <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> 下标从 1 开始</span>
[(1, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Spring</span><span style="color: rgba(128, 0, 0, 1)">'</span>), (2, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Summer</span><span style="color: rgba(128, 0, 0, 1)">'</span>), (3, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Fall</span><span style="color: rgba(128, 0, 0, 1)">'</span>), (4, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Winter</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">)]
</span>>>> tuple(enumerate(seasons, start=1<span style="color: rgba(0, 0, 0, 1)">))
((</span>1, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Spring</span><span style="color: rgba(128, 0, 0, 1)">'</span>), (2, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Summer</span><span style="color: rgba(128, 0, 0, 1)">'</span>), (3, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Fall</span><span style="color: rgba(128, 0, 0, 1)">'</span>), (4, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Winter</span><span style="color: rgba(128, 0, 0, 1)">'</span>))</pre>
</div>
<p> </p>
<h4><strong>普通的for循环</strong></h4>
<div class="cnblogs_code">
<pre>>>>i =<span style="color: rgba(0, 0, 0, 1)"> 0
</span>>>> seq = [<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">one</span><span style="color: rgba(128, 0, 0, 1)">'</span>, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">two</span><span style="color: rgba(128, 0, 0, 1)">'</span>, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">three</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">]
</span>>>> <span style="color: rgba(0, 0, 255, 1)">for</span> element <span style="color: rgba(0, 0, 255, 1)">in</span><span style="color: rgba(0, 0, 0, 1)"> seq:
... </span><span style="color: rgba(0, 0, 255, 1)">print</span><span style="color: rgba(0, 0, 0, 1)"> i, seq
... i </span>+=1<span style="color: rgba(0, 0, 0, 1)">
...
0 one
</span>1<span style="color: rgba(0, 0, 0, 1)"> two
</span>2 three</pre>
</div>
<h4><strong>for循环使用enumerate示例1</strong></h4>
<div class="cnblogs_code">
<pre>>>>seq = ['one', 'two', 'three'<span>]</span></pre>
<pre>>>><span style="color: rgba(0, 0, 255, 1)">for</span> temp <span style="color: rgba(0, 0, 255, 1)">in</span><span style="color: rgba(0, 0, 0, 1)"> enumerate(seq):
</span>>>> <span style="color: rgba(0, 0, 255, 1)">print</span><span style="color: rgba(0, 0, 0, 1)">(temp)

(0, </span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">one</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">)
(</span>1, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">two</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">)
(</span>2, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">three</span><span style="color: rgba(128, 0, 0, 1)">'</span>)</pre>
</div>
<h4><strong>for循环使用enumerate示例2</strong></h4>
<div class="cnblogs_code">
<pre>>>>seq = [<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">one</span><span style="color: rgba(128, 0, 0, 1)">'</span>, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">two</span><span style="color: rgba(128, 0, 0, 1)">'</span>, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">three</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">]
</span>>>> <span style="color: rgba(0, 0, 255, 1)">for</span> i, element <span style="color: rgba(0, 0, 255, 1)">in</span><span style="color: rgba(0, 0, 0, 1)"> enumerate(seq):
... </span><span style="color: rgba(0, 0, 255, 1)">print</span><span style="color: rgba(0, 0, 0, 1)"> (i, element)
...
0 one
</span>1<span style="color: rgba(0, 0, 0, 1)"> two
</span>2 three</pre>
</div>
<p> </p><br><br>
来源：https://www.cnblogs.com/yifchan/p/python-1-40.html

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