146 lines
42 KiB
JavaScript
146 lines
42 KiB
JavaScript
import{_ as s,c as i,o as a,a4 as n}from"./chunks/framework.DtvhUNIn.js";const F=JSON.parse('{"title":"阶段五：迭代生成","description":"","frontmatter":{},"headers":[],"relativePath":"技术资源汇总(杭电支持版)/3.编程思维体系构建/3.6.4.5阶段五：迭代生成.md","filePath":"技术资源汇总(杭电支持版)/3.编程思维体系构建/3.6.4.5阶段五：迭代生成.md"}'),t={name:"技术资源汇总(杭电支持版)/3.编程思维体系构建/3.6.4.5阶段五：迭代生成.md"},h=n(`<h1 id="阶段五-迭代生成" tabindex="-1">阶段五：迭代生成 <a class="header-anchor" href="#阶段五-迭代生成" aria-label="Permalink to "阶段五：迭代生成""></a></h1><h2 id="前言" tabindex="-1">前言 <a class="header-anchor" href="#前言" aria-label="Permalink to "前言""></a></h2><p>在写乘法表的时候，你可能写过类似</p><div class="language-python vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">python</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">for</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">in</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> [</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">7</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">11</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">13</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">]: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(i)</span></span></code></pre></div><p>这样的语句。for in 语句理解起来很直观形象，比起 C++ 和 java 早期的</p><div class="language-c vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">c</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">for</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">int</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">; i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"><</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> n; i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">++</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span></code></pre></div><p>这样的语句，不知道简洁清晰到哪里去了。</p><p>但是，你想过 Python 在处理 for in 语句的时候，具体发生了什么吗？什么样的对象可以被 for in 来枚举呢？</p><h2 id="容器迭代" tabindex="-1">容器迭代 <a class="header-anchor" href="#容器迭代" aria-label="Permalink to "容器迭代""></a></h2><p>容器这个概念非常好理解。</p><p>在 Python 中一切皆对象，对象的抽象就是类，而对象的集合就是容器。</p><p>列表<code>list: [0, 1, 2]</code>，元组<code>tuple: (0, 1, 2)</code>，字典<code>dict: {0:0, 1:1, 2:2}</code>，集合<code>set: set([0, 1, 2])</code>都是容器。</p><p>对于容器，你可以很直观地想象成多个元素在一起的单元；而不同容器的区别，正是在于内部数据结构的实现方法。</p><p>然后，你就可以针对不同场景，选择不同时间和空间复杂度的容器。所有的容器都是可迭代的（iterable）。</p><div class="language-python vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">python</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">iterator </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> iter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(iterable)</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> while</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> True</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> elem </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(iterator)</span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"> # do something</span></span></code></pre></div><ul><li>首先，在可迭代对象上调用内置 <code>iter</code> 函数以创建对应的<em>迭代器</em>。</li><li>要获取序列中的下一个元素，在此迭代器上调用内置 <code>next</code> 函数。</li></ul><p>如果没有下一个元素了，怎么办？</p><p>我们需要对这种异常进行处理。</p><p>思考题：什么是异常处理，为什么要进行异常处理？有什么好处？</p><p>多次调用 <code>iter</code> 可迭代对象每次都会返回一个具有不同状态的新迭代器</p><p>你也可以调用 <code>iter</code> 迭代器本身，它只会返回相同的迭代器而不改变它的状态。但是，请注意，您不能直接在可迭代对象上调用 next。</p><div class="language-python vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">python</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> lst </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> [</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">]</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(lst) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># Calling next on an iterable</span></span>
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<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">TypeError</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'list'</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> object</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> is</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> not</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> an iterator</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> list_iter </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> iter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(lst) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># Creates an iterator for the list</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> list_iter</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"><</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">list_iterator </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">object</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> ...</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">></span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(list_iter) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># Calling next on an iterator</span></span>
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<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(list_iter) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># Calling next on the same iterator</span></span>
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<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">iter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(list_iter)) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># Calling iter on an iterator returns itself</span></span>
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<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> list_iter2 </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> iter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(lst)</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(list_iter2) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># Second iterator has new state</span></span>
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<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(list_iter) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># First iterator is unaffected by second iterator</span></span>
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<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">4</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(list_iter) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># No elements left!</span></span>
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<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">StopIteration</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> lst </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># Original iterable is unaffected</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">[</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">]</span></span></code></pre></div><h2 id="英语练习-对迭代器的类比" tabindex="-1">英语练习，对迭代器的类比 <a class="header-anchor" href="#英语练习-对迭代器的类比" aria-label="Permalink to "英语练习，对迭代器的类比""></a></h2><p><strong>Analogy</strong>: An iterable is like a book (one can flip through the pages) and an iterator for a book would be a bookmark (saves the position and can locate the next page). Calling <code>iter</code> on a book gives you a new bookmark independent of other bookmarks, but calling <code>iter</code> on a bookmark gives you the bookmark itself, without changing its position at all. Calling <code>next</code> on the bookmark moves it to the next page, but does not change the pages in the book. Calling <code>next</code> on the book wouldn't make sense semantically. We can also have multiple bookmarks, all independent of each other.</p><h2 id="生成器-懒人迭代器" tabindex="-1">生成器：懒人迭代器！ <a class="header-anchor" href="#生成器-懒人迭代器" aria-label="Permalink to "生成器：懒人迭代器！""></a></h2><div class="language-python vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">python</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> test_iterator</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">():</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> show_memory_info(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'initing iterator'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> list_1 </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> [i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">for</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">in</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> range</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">100000000</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)]</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> show_memory_info(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'after iterator initiated'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
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<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">sum</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(list_1))</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> show_memory_info(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'after sum called'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> test_generator</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">():</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> show_memory_info(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'initing generator'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> list_2 </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">for</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">in</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> range</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">100000000</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">))</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> show_memory_info(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'after generator initiated'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
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<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> print</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">sum</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(list_2))</span></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> show_memory_info(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">'after sum called'</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">%</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">time test_iterator()</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">%</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">time test_generator()</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">########## 输出 ##########</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">initing iterator memory used: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">48.9765625</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> MB</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">after iterator initiated memory used: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3920.30078125</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> MB</span></span>
|
||
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">4999999950000000</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">after </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">sum</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> called memory used: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3920.3046875</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> MB</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">Wall time: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">17</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> s</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">initing generator memory used: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">50.359375</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> MB</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">after generator initiated memory used: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">50.359375</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> MB</span></span>
|
||
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">4999999950000000</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">after </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">sum</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> called memory used: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">50.109375</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> MB</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">Wall time: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">12.5</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> s</span></span></code></pre></div><p>声明一个迭代器很简单，[i for i in range(100000000)]就可以生成一个包含一亿元素的列表。每个元素在生成后都会保存到内存中，你通过代码可以看到，它们占用了巨量的内存，内存不够的话就会出现 OOM 错误。</p><div class="warning custom-block"><p class="custom-block-title">🤔 了解下 yield（）函数吧，他可以返回一个生成器对象，试试看懂这个</p></div><div class="language-python vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">python</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> gen_list</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(lst):</span></span>
|
||
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">...</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> yield from</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> lst</span></span>
|
||
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">...</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> g </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> gen_list([</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">])</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(g)</span></span>
|
||
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(g)</span></span>
|
||
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(g)</span></span>
|
||
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(g)</span></span>
|
||
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">4</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(g)</span></span>
|
||
<span class="line"><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">StopIteration</span></span></code></pre></div><h2 id="思考题-python-会显示什么-为什么" tabindex="-1">思考题：python 会显示什么？为什么？ <a class="header-anchor" href="#思考题-python-会显示什么-为什么" aria-label="Permalink to "思考题：python 会显示什么？为什么？""></a></h2><div class="language-python vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">python</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> s </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> [</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">]</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> t </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> iter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(s)</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(s)</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">______</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(t)</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">______</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(t)</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">______</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> iter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(s)</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">______</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">iter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(s))</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">______</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">iter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(t))</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">______</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">iter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(s))</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">______</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">iter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(t))</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">______</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(t)</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">______</span></span></code></pre></div><div class="language-python vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">python</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> r </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> range</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">6</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> r_iter </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> iter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(r)</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(r_iter)</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">______</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> [x </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> for</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> x </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">in</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> r]</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">______</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> [x </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> for</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> x </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">in</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> r_iter]</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">______</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> next</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(r_iter)</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">______</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">>>></span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> list</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">range</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)) </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># Converts an iterable into a list</span></span>
|
||
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">______</span></span></code></pre></div><h2 id="任务" tabindex="-1">任务 <a class="header-anchor" href="#任务" aria-label="Permalink to "任务""></a></h2><p>P10：实现 <code>count</code>，它接受一个迭代器 <code>t</code> 并返回该值 <code>x</code> 出现在的前 n 个元素中的次数 <code>t</code></p><div class="language-python vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">python</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> count</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(t, n, x):</span></span>
|
||
<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """Return the number of times that x appears in the first n elements of iterator t.</span></span>
|
||
<span class="line"></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">s = iter([10, 9, 10, 9, 9, 10, 8, 8, 8, 7])</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">count(s, 10, 9)</span></span>
|
||
<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> 3</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">s2 = iter([10, 9, 10, 9, 9, 10, 8, 8, 8, 7])</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">count(s2, 3, 10)</span></span>
|
||
<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> 2</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">s = iter([3, 2, 2, 2, 1, 2, 1, 4, 4, 5, 5, 5])</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">count(s, 1, 3)</span></span>
|
||
<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> 1</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">count(s, 4, 2)</span></span>
|
||
<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> 3</span></span>
|
||
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">next(s)</span></span>
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<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> 2</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">s2 = iter([4, 1, 6, 6, 7, 7, 8, 8, 2, 2, 2, 5])</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">count(s2, 6, 6)</span></span>
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<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> 2</span></span>
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<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """</span></span>
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<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> "*** YOUR CODE HERE ***"</span></span></code></pre></div><p>P11:实现生成器函数 <code>scale(it, multiplier)</code>，它产生给定迭代的元素 <code>it</code>，按 <code>multiplier</code>.</p><p>同时也希望你尝试使用 <code>yield from</code> 语句编写这个函数！</p><div class="language-python vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">python</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">def</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> scale</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(it, multiplier):</span></span>
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<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """Yield elements of the iterable it scaled by a number multiplier.</span></span>
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<span class="line"></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">m = scale(iter([1, 5, 2]), 5)</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">type(m)</span></span>
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<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> <class 'generator'></span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">list(m)</span></span>
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<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> [5, 25, 10]</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"># generators allow us to represent infinite sequences!!!</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">def naturals():</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> ... </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> i = 0</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> ... </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> while True:</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> ... </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> yield i</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> ... </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> i += 1</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">m = scale(naturals(), 2)</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> >>> </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">[next(m) for _ in range(5)]</span></span>
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<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> [0, 2, 4, 6, 8]</span></span>
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<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> """</span></span>
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<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> "*** YOUR CODE HERE ***"</span></span></code></pre></div>`,38),l=[h];function p(k,e,g,r,E,d){return a(),i("div",null,l)}const o=s(t,[["render",p]]);export{F as __pageData,o as default};
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