Python的初学者,开发者都应该知道的代码可读性提高技巧,本篇主要介绍了如下内容: PEP 8是什么以及它存在的原因 为什么你应该编写符合PEP 8标准的代码 如何编写符合PEP 8的代码 为什么我们需要PEP 8? PEP 8 的存在是为了提高Python代码的可读性的.但为什么可读性如此重要?为什么编写可读代码是Python语言的指导原则之一? 正如Guido van Rossum所说:“代码的阅读频率远高于编写代码的频率”.比如,你可能花费几分钟或一整天的时间编写一段代码.一旦你写完它,…

学 Python 怎样才最快,当然是实战各种小项目,只有自己去想与写,才记得住规则.本文是 30 个极简任务,初学者可以尝试着自己实现:本文同样也是 30 段代码,Python 开发者也可以看看是不是有没想到的用法. Python 是机器学习最广泛采用的编程语言,它最重要的优势在于编程的易用性.如果读者对基本的 Python 语法已经有一些了解,那么这篇文章可能会给你一些启发.作者简单概览了 30 段代码,它们都是平常非常实用的技巧,我们只要花几分钟就能从头到尾浏览一遍. 1. 重复元素判定 以…

Pythonic其实是个模糊的含义,没有确定的解释.网上也没有过多关于Pythonic的说明,我个人的理解是更加Python,更符合Python的行为习惯.本文主要是说明一些Python的惯用法和小技巧,其实与上一篇<编码规范>有异曲同工之妙,都是为了增加代码可读性,但Pythonic可能还会从性能的角度进行考虑. 首先是两个不得不说的Python的特性List Comprehension和Generator Expression,非常精简的语法,很大程度上取代了冗长for循环. 1. 列表解…

版权声明:本文为博主原创文章,未经博主允许不得转载. https://blog.csdn.net/xie_0723/article/details/52790786 关于 Python Requests ,在使用中,总结了一些小技巧把,分享下. 1:保持请求之间的Cookies,我们可以这样做. import requests self.session = requests.Session() self.session.get(login_url) # 可以保持登录态 1 2 3 2:请求时,会…

python - opencv 的一些小技巧备忘 使用python-opencv来处理图像时,可以像matlab一样,将一幅图像看成一个矩阵,进行矢量操作,以加快代码运行速度. 下面记录几个常用的操作以备忘 1.求取图像中像素值满足特定条件的掩模图像(mask) mask = imge < (b, g, r) 这个操作返回的mask大小与image相等,通道数也相等,独立判断每个通道的像素值是否满足条件. mask = (image < (b, g, r)).all(axis = 2) 这个操…

Python语言防坑小技巧 作者:尹正杰 版权声明:原创作品,谢绝转载!否则将追究法律责任. 一.赋值即定义  1>.运行以下代码会出现报错 #!/usr/bin/env python #_*_conding:utf-8_*_ #@author :yinzhengjie #blog:http://www.cnblogs.com/yinzhengjie x = 100 def outer(): def inner(): x += 100 #其实这里等效于"x = x + 100",…

python实用30个小技巧 展开1.原地交换两个数字Python 提供了一个直观的在一行代码中赋值与交换(变量值)的方法,请参见下面的示例: In [1]: x,y = 10 ,20 In [2]: print(x,y) 10 20 In [3]: x, y = y, x In [4]: print(x,y) 20 10 赋值的右侧形成了一个新的元组,左侧立即解析(unpack)那个(未被引用的)元组到变量 <x> 和 <y>. 一旦赋值完成,新的元组变成了未被引用状态并且被标记…

摘要:最近服务遇到了内存泄漏问题,运维同学紧急呼叫解决,于是在解决问题之余也系统记录了下内存泄漏问题的常见解决思路. 本文分享自华为云社区<python内存泄漏排查小技巧>,作者:lutianfei. 最近服务遇到了内存泄漏问题,运维同学紧急呼叫解决,于是在解决问题之余也系统记录了下内存泄漏问题的常见解决思路. 首先搞清楚了本次问题的现象: 1. 服务在13号上线过一次,而从23号开始,出现内存不断攀升问题,达到预警值重启实例后,攀升速度反而更快. 2. 服务分别部署在了A.B 2种芯片上,但…

一,什么是代码块. 根据官网提示我们可以获知: 根据提示我们从官方文档找到了这样的说法: A Python program is constructed from code blocks. A block is a piece of Python program text that is executed as a unit. The following are blocks: a module, a function body, and a class definition. Each com…

import tkinter import tkinter.messagebox import math class JSQ: def __init__(self): #创建主界面 self.root = tkinter.Tk() self.root.minsize(270, 330) self.root.maxsize(270, 330) self.root.title('小可乐的计算器') #定义一个变量赋值给页面label self.result = tkinter.StringVar()…

Github搜索之代码搜索 可以使用下列搜索限定符的任意组合进行代码搜索 提示:通过将一连串的搜索语法添加到搜索限定符来进一步提高搜索结果的精度. ·代码搜索注意事项 由于搜索代码的复杂性,有一些搜索限制: ·默认搜索是从master分支搜索代码. ·只有小于384 KB的文件是可搜索的. ·在搜索源代码时,必须至少包含一个搜索词. 例如,搜索:language:go 是无效的,而 amazing language:go 则是有效的 ·在大多数情况下,搜索结果可以显示同一个文件中的两个片段, 但…

这里是本人收集的一些 Python 小技巧,目前主要是一些实用函数,适合有一定基础的童鞋观看(不会专门介绍使用到的标准库函数).. 一.函数式编程 函数式编程用来处理数据,感觉很方便.(要是再配上管道操作符 | 或者 Java 的那种链式调用,超级爽!可惜 Python 都没有..需要借助第三方库) 1. 分组/group 数据处理中一个常见的操作,是将列表中的元素,依次每 k 个分作一组. def group_each(a, size: int):     """     …

(27)Throw hardware at the problem, not developers 招数27: 把问题仍给硬件而不是开发人员 As developers, we often want to fix problems with code, but don’t be afraid to ‘put the compiler down’ and throw some hardware at the problem.作为开发人员,我们通常想通过代码解决问题,但不要害怕‘批评编译器’和把问题…

Database Performance Tips for Developers对于开发人员的数据库性能技巧 As a developer you may or may not need to go into the database and write queries or design tables and indexes, or help determine configuration of your SQL Server systems. But if you do, these tip…

ORM TipsORM小窍门 More and more people are using Object to Relational Mapping (ORM) tools to jump the divide between application code that is object oriented and a database that is storing information in a relational manner. These tools are excellent an…

(41)StringBuilder is NOT the answer for all string concatenation scenarios; String.Join could be 招数41: StringBuilder不适用于所有字符串连接的场景:String.Join可能是 Yes, if you are in a loop and adding to a string, then a StringBuilder *could* be most appropriate. Howe…

(40)Take advantage of .NET 4.5 async constructs 招数40: 利用.NET 4.5异步结构 With the arrival of .NET 4.5, writing async code correctly is easier than ever. Like any tool, it should be only applied where it makes most sense – in web use-cases this usually re…

(32)Seven handy ViewState tips 招数32: 7条便利的ViewState技巧 Every time I have to deal with a classic ASP.NET Web Forms application, one of the first things I look at is the resulting source, to check whether the DOM is a complete mess and whether the ViewS…

(31)Know your loops 招数31: 认识你的循环 for is the fastest way of iterating over a collection, foreach is a little slower, and LINQ queries are slowest.for是遍历集合最快的方法,foreach略慢一些,LINQ查询最慢. 测试代码: using System; using System.Collections.Generic; using System.Li…

(28)Don’t assume that problems can only arise from business logic 招数28: 不要认为问题只会从业务层产生 When beginning to diagnose performance problems, we often assume the problem is in our business logic. Don’t forget that the areas of our code that provide infrast…

(26)Don’t underestimate the value of the UI when tackling performance problems 招数26: 解决性能问题时不要低估UI的价值 Simple UI tricks, such as progress bars, redirecting users’ attention using animation, or placing slower loading sections at the bottom of a page or…

(16)Reduce the data sent across the network 招数16: 减少通过网络发送的数据 Reducing the amount of data sent across the network can improve application performance significantly. Compressing CSS and JavaScript is possible using bundling and minification. This will…

(13)Always perform validation on the server as well 招数13: 总是在服务器端执行验证 This isn’t exactly a performance tip but rather a security tip for when people think that they could improve performance by cutting out server-side validation. These days, client-s…

(2)Remove unused View Engines 招数2: 移除不用的视图引擎 If you're an ASP.NET MVC developer, you might not know that ASP.NET still loads the View Engines for both Razor and Web Forms by default. This can cause performance issues because MVC will normally look fo…

(1)Caching is a last resort 招数1: 缓存是最后的手段 Projects that use multiple levels of cache often demonstrate a misunderstanding of why caching is required in the first place. 项目中使用多重缓存经常会表现会产生误会,为什么缓存是第一步必须的. Caching is not synonymous with performance. You…

(39)Avoid using session state 招数39: 避免使用会话状态 Where possible, you should try and avoid using session state. Whilst using one web server, performance is usually not a problem. This changes as soon as you need to scale to multiple servers, as different,…

(30)Static collections 招数30: 静态集合 If a collection is static, make sure it only contains the objects you need. If the collection is iterated over often, then the performance can be slow if you don’t remove unnecessary objects. Objects in a collection…

(29)Before tackling any website performance issue, first verify the problem isn’t on the client 招数29: 在处理网站性能问题前,首先验证问题是否出在客户端 Traditionally, many performance problems have been rooted in either the database or application server. 习惯上,许多性能问题要么根植于数据库或…

(25)Use the startMode attribute to reduce the load time for your ASP.NET site 招数25: 使用startMode属性来减少ASP.NET站点加载时间 Every time you update your site, IIS must recompile it during the first request, so the initial request takes significantly longer than…

(19)A selection of tips 招数19: 精选技巧集合 Including height and width in <img /> tags will allow your page to render more quickly, because space can be allocated for the image before it is downloaded.在<img />标签中包括height和width属性会加速你的页面呈现,因为下载完成之前空间可以…