分享一些非常实用的Python代码，建议收藏！

知行编程网 2022-07-23 05:00 知行编程网 | 隐藏边栏 | 抢沙发 | 2 0

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据说Python之父-Guido Van Rossum打算让CPython更快，速度直接翻五倍，这是实实在在的好消息。

Python一直以来被诟病速度慢，影响开发效率，希望这次Guido老爷子能帮python打一场漂亮的翻身仗。

这篇文章不准备介绍Python速度如何，而是给大家带来一些常用且实用的Python代码实例，几乎是开发者必备的知识点。

1、合并两个字典

Python3.5之后，合并字典变得容易起来。我们可以通过**符号解压字典，并将多个字典传入{}中，实现合并。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;"><span style="line-height: 26px;"><span style="color: #c678dd;line-height: 26px;">def</span> <span style="color: #61aeee;line-height: 26px;">Merge</span><span style="line-height: 26px;">(dict1, dict2)</span>:</span> <br  />    res = {**dict1, **dict2} <br  />    <span style="color: #c678dd;line-height: 26px;">return</span> res <br  />      <br  /><span style="color: #5c6370;font-style: italic;line-height: 26px;"># 两个字典</span><br  />dict1 = {<span style="color: #98c379;line-height: 26px;">"name"</span>: <span style="color: #98c379;line-height: 26px;">"Joy"</span>, <span style="color: #98c379;line-height: 26px;">"age"</span>: <span style="color: #d19a66;line-height: 26px;">25</span>}<br  />dict2 = {<span style="color: #98c379;line-height: 26px;">"name"</span>: <span style="color: #98c379;line-height: 26px;">"Joy"</span>, <span style="color: #98c379;line-height: 26px;">"city"</span>: <span style="color: #98c379;line-height: 26px;">"New York"</span>}<br  />dict3 = Merge(dict1, dict2) <br  />print(dict3)<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">{<span style="color: #98c379;line-height: 26px;">'name'</span>: <span style="color: #98c379;line-height: 26px;">'Joy'</span>, <span style="color: #98c379;line-height: 26px;">'age'</span>: 25, <span style="color: #98c379;line-height: 26px;">'city'</span>: <span style="color: #98c379;line-height: 26px;">'New York'</span>}<br  /></p>

2、链式比较

python有链式比较的机制，在一行里支持多种运算符比较。相当于拆分多个逻辑表达式，再进行逻辑与操作。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">a = <span style="color: #d19a66;line-height: 26px;">5</span><br  /><br  />print(<span style="color: #d19a66;line-height: 26px;">2</span> < a < <span style="color: #d19a66;line-height: 26px;">8</span>)<br  />print(<span style="color: #d19a66;line-height: 26px;">1</span> == a < <span style="color: #d19a66;line-height: 26px;">3</span>)<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">True<br  />False<br  /></p>

3、重复打印字符串

将一个字符串重复打印多次，一般使用循环实现，但有更简易的方式可以实现。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">n = <span style="color: #d19a66;line-height: 26px;">5</span><br  />string = <span style="color: #98c379;line-height: 26px;">"Hello!"</span><br  /><br  />print(string * n)<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">Hello!Hello!Hello!Hello!Hello!<br  /></p>

4、检查文件是否存在

我们知道Python有专门处理系统交互的模块-os，它可以处理文件的各种增删改查操作。

那如何检查一个文件是否存在呢？os模块可以轻松实现。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;"><span style="color: #c678dd;line-height: 26px;">from</span> os <span style="color: #c678dd;line-height: 26px;">import</span> path<br  /><br  /><span style="line-height: 26px;"><span style="color: #c678dd;line-height: 26px;">def</span> <span style="color: #61aeee;line-height: 26px;">check_for_file</span><span style="line-height: 26px;">()</span>:</span><br  />    print(<span style="color: #98c379;line-height: 26px;">"Does file exist:"</span>, path.exists(<span style="color: #98c379;line-height: 26px;">"data.csv"</span>))<br  /><br  /><span style="color: #c678dd;line-height: 26px;">if</span> __name__==<span style="color: #98c379;line-height: 26px;">"__main__"</span>:<br  />    check_for_file()<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">Does file exist: False<br  /></p>

5、检索列表最后一个元素

在使用列表的时候，有时会需要取最后一个元素，有下面几种方式可以实现。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">my_list = [<span style="color: #98c379;line-height: 26px;">'banana'</span>, <span style="color: #98c379;line-height: 26px;">'apple'</span>, <span style="color: #98c379;line-height: 26px;">'orange'</span>, <span style="color: #98c379;line-height: 26px;">'pineapple'</span>]<br  /><br  /><span style="color: #5c6370;font-style: italic;line-height: 26px;">#索引方法</span><br  />last_element = my_list[<span style="color: #d19a66;line-height: 26px;">-1</span>]<br  /><br  /><span style="color: #5c6370;font-style: italic;line-height: 26px;">#pop方法</span><br  />last_element = my_list.pop()<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;"><span style="color: #98c379;line-height: 26px;">'pineapple'</span><br  /></p>

6、列表推导式

列表推导式是for循环的简易形式，可以在一行代码里创建一个新列表，同时能通过if语句进行判断筛选

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;"><span style="line-height: 26px;"><span style="color: #c678dd;line-height: 26px;">def</span> <span style="color: #61aeee;line-height: 26px;">get_vowels</span><span style="line-height: 26px;">(string)</span>:</span><br  />    <span style="color: #c678dd;line-height: 26px;">return</span> [vowel <span style="color: #c678dd;line-height: 26px;">for</span> vowel <span style="color: #c678dd;line-height: 26px;">in</span> string <span style="color: #c678dd;line-height: 26px;">if</span> vowel <span style="color: #c678dd;line-height: 26px;">in</span> <span style="color: #98c379;line-height: 26px;">'aeiou'</span>] <br  /><br  />print(<span style="color: #98c379;line-height: 26px;">"Vowels are:"</span>, get_vowels(<span style="color: #98c379;line-height: 26px;">'This is some random string'</span>))<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">Vowels are:  [<span style="color: #98c379;line-height: 26px;">'i'</span>, <span style="color: #98c379;line-height: 26px;">'i'</span>, <span style="color: #98c379;line-height: 26px;">'o'</span>, <span style="color: #98c379;line-height: 26px;">'e'</span>, <span style="color: #98c379;line-height: 26px;">'a'</span>, <span style="color: #98c379;line-height: 26px;">'o'</span>, <span style="color: #98c379;line-height: 26px;">'i'</span>]<br  /></p>

7、计算代码执行时间

python中time模块提供了时间处理相关的各种函数方法，我们可以使用它来计算代码执行的时间。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;"><span style="color: #c678dd;line-height: 26px;">import</span> time<br  /><br  />start_time = time.time()<br  /><br  />total = <span style="color: #d19a66;line-height: 26px;">0</span><br  /><span style="color: #c678dd;line-height: 26px;">for</span> i <span style="color: #c678dd;line-height: 26px;">in</span> range(<span style="color: #d19a66;line-height: 26px;">10</span>):<br  />  total += i<br  />print(<span style="color: #98c379;line-height: 26px;">"Sum:"</span>, total)<br  /><br  />end_time = time.time()<br  />time_taken = end_time - start_time<br  />print(<span style="color: #98c379;line-height: 26px;">"Time: "</span>, time_taken)<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">Sum: 45<br  />Time:  0.0009975433349609375<br  /></p>

8、查找出现次数最多的元素

使用max方法找出列表中出现次数最多的元素。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;"><span style="line-height: 26px;"><span style="color: #c678dd;line-height: 26px;">def</span> <span style="color: #61aeee;line-height: 26px;">most_frequent</span><span style="line-height: 26px;">(list)</span>:</span><br  />  <span style="color: #c678dd;line-height: 26px;">return</span> max(set(list), key=list.count)<br  /><br  />mylist = [<span style="color: #d19a66;line-height: 26px;">1</span>,<span style="color: #d19a66;line-height: 26px;">1</span>,<span style="color: #d19a66;line-height: 26px;">2</span>,<span style="color: #d19a66;line-height: 26px;">3</span>,<span style="color: #d19a66;line-height: 26px;">4</span>,<span style="color: #d19a66;line-height: 26px;">5</span>,<span style="color: #d19a66;line-height: 26px;">6</span>,<span style="color: #d19a66;line-height: 26px;">6</span>,<span style="color: #d19a66;line-height: 26px;">2</span>,<span style="color: #d19a66;line-height: 26px;">2</span>]<br  />print(<span style="color: #98c379;line-height: 26px;">"出现次数最多的元素是:"</span>, most_frequent(mylist))<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">出现次数最多的元素是: <span style="color: #d19a66;line-height: 26px;">2</span><br  /></p>

9、将两个列表转换为字典

有两个列表，将列表A里的元素作为键，将列表B里的对应元素作为值，组成一个字典。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;"><span style="line-height: 26px;"><span style="color: #c678dd;line-height: 26px;">def</span> <span style="color: #61aeee;line-height: 26px;">list_to_dictionary</span><span style="line-height: 26px;">(keys, values)</span>:</span><br  />  <span style="color: #c678dd;line-height: 26px;">return</span> dict(zip(keys, values))<br  /><br  />list1 = [<span style="color: #d19a66;line-height: 26px;">1</span>, <span style="color: #d19a66;line-height: 26px;">2</span>, <span style="color: #d19a66;line-height: 26px;">3</span>]<br  />list2 = [<span style="color: #98c379;line-height: 26px;">'one'</span>, <span style="color: #98c379;line-height: 26px;">'two'</span>, <span style="color: #98c379;line-height: 26px;">'three'</span>]<br  /><br  />print(list_to_dictionary(list1, list2))<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">{1: <span style="color: #98c379;line-height: 26px;">'one'</span>, 2: <span style="color: #98c379;line-height: 26px;">'two'</span>, 3: <span style="color: #98c379;line-height: 26px;">'three'</span>}<br  /></p>

10、异常处理

Python提供了try...except...finally的方式来处理代码异常，当然还有其他组合的方式。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">a, b = <span style="color: #d19a66;line-height: 26px;">1</span>,<span style="color: #d19a66;line-height: 26px;">0</span><br  /><br  /><span style="color: #c678dd;line-height: 26px;">try</span>:<br  />    print(a/b)<br  /><span style="color: #c678dd;line-height: 26px;">except</span> ZeroDivisionError:<br  />    print(<span style="color: #98c379;line-height: 26px;">"Can not divide by zero"</span>)<br  /><span style="color: #c678dd;line-height: 26px;">finally</span>:<br  />    print(<span style="color: #98c379;line-height: 26px;">"Executing finally block"</span>)<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">Can not divide by zero<br  />Executing finally block<br  /></p>

11、反转字符串

使用切片操作对字符串进行反转，这是比较直接有效的方式。这也可以用来检测回文数。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">str = <span style="color: #98c379;line-height: 26px;">"Hello World"</span><br  /><br  />print(<span style="color: #98c379;line-height: 26px;">"反转后字符串是:"</span>, str[::<span style="color: #d19a66;line-height: 26px;">-1</span>])<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">反转后字符串是: dlroW olleH<br  /></p>

12、字符串列表组成单个字符串

使用join方法将字符串列表组成单个字符串。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">list = [<span style="color: #98c379;line-height: 26px;">"Hello"</span>, <span style="color: #98c379;line-height: 26px;">"world"</span>, <span style="color: #98c379;line-height: 26px;">"Ok"</span>, <span style="color: #98c379;line-height: 26px;">"Bye!"</span>]<br  />combined_string = <span style="color: #98c379;line-height: 26px;">" "</span>.join(list)<br  /><br  />print(combined_string)<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">Hello world Ok Bye!<br  /></p>

13、返回字典缺失键的默认值

字典中的get方法用于返回指定键的值，如果键不在字典中返回默认值 None 或者设置的默认值。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">dict = {<span style="color: #d19a66;line-height: 26px;">1</span>:<span style="color: #98c379;line-height: 26px;">'one'</span>, <span style="color: #d19a66;line-height: 26px;">2</span>:<span style="color: #98c379;line-height: 26px;">'two'</span>, <span style="color: #d19a66;line-height: 26px;">4</span>:<span style="color: #98c379;line-height: 26px;">'four'</span>}<br  /><br  /><span style="color: #5c6370;font-style: italic;line-height: 26px;">#returning three as default value</span><br  />print(dict.get(<span style="color: #d19a66;line-height: 26px;">3</span>, <span style="color: #98c379;line-height: 26px;">'three'</span>))<br  /><br  />print(<span style="color: #98c379;line-height: 26px;">"原始字典:"</span>, dict) <br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">three<br  />原始字典: {1: <span style="color: #98c379;line-height: 26px;">'one'</span>, 2: <span style="color: #98c379;line-height: 26px;">'two'</span>, 4: <span style="color: #98c379;line-height: 26px;">'four'</span>}<br  /></p>

14、交换两个变量的值

在不使用临时变量的前提下，交换两个变量的值。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">a, b = <span style="color: #d19a66;line-height: 26px;">5</span>, <span style="color: #d19a66;line-height: 26px;">10</span><br  /><br  /><span style="color: #5c6370;font-style: italic;line-height: 26px;"># 方法1</span><br  />a, b = b, a<br  /><br  /><span style="color: #5c6370;font-style: italic;line-height: 26px;"># 方法2</span><br  /><span style="line-height: 26px;"><span style="color: #c678dd;line-height: 26px;">def</span> <span style="color: #61aeee;line-height: 26px;">swap</span><span style="line-height: 26px;">(a,b)</span>:</span><br  />  <span style="color: #c678dd;line-height: 26px;">return</span> b,a<br  />swap(a,b)<br  /></p>

15、正则表达式

正则表达式用来匹配处理字符串，python中的re模块提供了全部的正则功能。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;"><span style="color: #c678dd;line-height: 26px;">import</span> re<br  /><br  />text = <span style="color: #98c379;line-height: 26px;">"The rain in spain"</span><br  />result = re.search(<span style="color: #98c379;line-height: 26px;">"rain"</span>, text)<br  /><br  />print(<span style="color: #56b6c2;line-height: 26px;">True</span> <span style="color: #c678dd;line-height: 26px;">if</span> result <span style="color: #c678dd;line-height: 26px;">else</span> <span style="color: #56b6c2;line-height: 26px;">False</span>)<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">True<br  /></p>

16、筛选值

python中的filter方法可以用来进行值的筛选。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">my_list = [<span style="color: #d19a66;line-height: 26px;">0</span>,<span style="color: #d19a66;line-height: 26px;">1</span>,<span style="color: #d19a66;line-height: 26px;">2</span>,<span style="color: #d19a66;line-height: 26px;">3</span>,<span style="color: #d19a66;line-height: 26px;">6</span>,<span style="color: #d19a66;line-height: 26px;">7</span>,<span style="color: #d19a66;line-height: 26px;">9</span>,<span style="color: #d19a66;line-height: 26px;">11</span>]<br  /><br  />result = filter(<span style="color: #c678dd;line-height: 26px;">lambda</span> x: x % <span style="color: #d19a66;line-height: 26px;">2</span>!=<span style="color: #d19a66;line-height: 26px;">0</span>, my_list)<br  /><br  />print(list(result))<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">[1, 3, 7, 9, 11]<br  /></p>

17、统计字频

判断字符串每个元素出现的次数，可以用collections模块中的Counter方法来实现，非常简洁。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;"><span style="color: #c678dd;line-height: 26px;">from</span> collections <span style="color: #c678dd;line-height: 26px;">import</span> Counter<br  />result = Counter(<span style="color: #98c379;line-height: 26px;">'banana'</span>)<br  />print(result)<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">Counter({<span style="color: #98c379;line-height: 26px;">'a'</span>: 3, <span style="color: #98c379;line-height: 26px;">'n'</span>: 2, <span style="color: #98c379;line-height: 26px;">'b'</span>: 1})<br  /></p>

18、变量的内存占用

如何输出python中变量的内存占用大小，可以通过sys模块来实现。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;"><span style="color: #c678dd;line-height: 26px;">import</span> sys<br  /><br  />var1 = <span style="color: #d19a66;line-height: 26px;">15</span><br  />list1 = [<span style="color: #d19a66;line-height: 26px;">1</span>,<span style="color: #d19a66;line-height: 26px;">2</span>,<span style="color: #d19a66;line-height: 26px;">3</span>,<span style="color: #d19a66;line-height: 26px;">4</span>,<span style="color: #d19a66;line-height: 26px;">5</span>]<br  /><br  />print(sys.getsizeof(var1))<br  />print(sys.getsizeof(list1))<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">28<br  />104<br  /></p>

19、链式函数调用

在一行代码中调用多个函数。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;"><span style="line-height: 26px;"><span style="color: #c678dd;line-height: 26px;">def</span> <span style="color: #61aeee;line-height: 26px;">add</span><span style="line-height: 26px;">(a, b)</span>:</span><br  />    <span style="color: #c678dd;line-height: 26px;">return</span> a + b<br  /><br  /><span style="line-height: 26px;"><span style="color: #c678dd;line-height: 26px;">def</span> <span style="color: #61aeee;line-height: 26px;">subtract</span><span style="line-height: 26px;">(a, b)</span>:</span><br  />    <span style="color: #c678dd;line-height: 26px;">return</span> a - b<br  /><br  />a, b = <span style="color: #d19a66;line-height: 26px;">5</span>, <span style="color: #d19a66;line-height: 26px;">10</span><br  /><br  />print((add <span style="color: #c678dd;line-height: 26px;">if</span> b > a <span style="color: #c678dd;line-height: 26px;">else</span> subtract)(a,b))<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">15<br  /></p>

20、从列表中删除重复项

删除列表中重复项一般可以通过遍历来筛选去重，或者直接使用集合方法。

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">list1 = [<span style="color: #d19a66;line-height: 26px;">1</span>,<span style="color: #d19a66;line-height: 26px;">2</span>,<span style="color: #d19a66;line-height: 26px;">3</span>,<span style="color: #d19a66;line-height: 26px;">3</span>,<span style="color: #d19a66;line-height: 26px;">4</span>,<span style="color: #98c379;line-height: 26px;">'John'</span>, <span style="color: #98c379;line-height: 26px;">'Ana'</span>, <span style="color: #98c379;line-height: 26px;">'Mark'</span>, <span style="color: #98c379;line-height: 26px;">'John'</span>]<br  /><br  /><span style="color: #5c6370;font-style: italic;line-height: 26px;"># 方法1</span><br  /><span style="line-height: 26px;"><span style="color: #c678dd;line-height: 26px;">def</span> <span style="color: #61aeee;line-height: 26px;">remove_duplicate</span><span style="line-height: 26px;">(list_value)</span>:</span><br  />    <span style="color: #c678dd;line-height: 26px;">return</span> list(set(list_value))<br  />print(remove_duplicate(list1))<br  /><br  /><span style="color: #5c6370;font-style: italic;line-height: 26px;"># 方法2</span><br  />result = []<br  />[result.append(x) <span style="color: #c678dd;line-height: 26px;">for</span> x <span style="color: #c678dd;line-height: 26px;">in</span> list1 <span style="color: #c678dd;line-height: 26px;">if</span> x <span style="color: #c678dd;line-height: 26px;">not</span> <span style="color: #c678dd;line-height: 26px;">in</span> result]<br  />print(result)<br  /></p>

输出：

<p style="overflow-x: auto;padding: 15px 16px 16px;color: rgb(171, 178, 191);display: -webkit-box;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;font-size: 12px;background: rgb(40, 44, 52);border-radius: 5px;">[1, 2, 3, 4, <span style="color: #98c379;line-height: 26px;">'Ana'</span>, <span style="color: #98c379;line-height: 26px;">'John'</span>, <span style="color: #98c379;line-height: 26px;">'Mark'</span>]<br  />[1, 2, 3, 4, <span style="color: #98c379;line-height: 26px;">'John'</span>, <span style="color: #98c379;line-height: 26px;">'Ana'</span>, <span style="color: #98c379;line-height: 26px;">'Mark'</span>]<br  /></p>

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1、合并两个字典

2、链式比较

3、重复打印字符串

4、检查文件是否存在

5、检索列表最后一个元素

6、列表推导式

7、计算代码执行时间

8、查找出现次数最多的元素

9、将两个列表转换为字典

10、异常处理

11、反转字符串

12、字符串列表组成单个字符串

13、返回字典缺失键的默认值

14、交换两个变量的值

15、正则表达式

16、筛选值

17、统计字频

18、变量的内存占用

19、链式函数调用

20、从列表中删除重复项

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分享一些非常实用的Python代码，建议收藏！

1、合并两个字典

2、链式比较

3、重复打印字符串

4、检查文件是否存在

5、检索列表最后一个元素

6、列表推导式

7、计算代码执行时间

8、查找出现次数最多的元素

9、将两个列表转换为字典

10、异常处理

11、反转字符串

12、字符串列表组成单个字符串

13、返回字典缺失键的默认值

14、交换两个变量的值

15、正则表达式

16、筛选值

17、统计字频

18、变量的内存占用

19、链式函数调用

20、从列表中删除重复项

分享本文海报

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