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How to quickly start Python web crawler, in view of this problem, this article introduces the corresponding analysis and answer in detail, hoping to help more partners who want to solve this problem to find a more simple and easy way.

Preface

Python web crawler starts quickly and can get started as soon as possible, but it does take some time to master it, and it takes pains to reach the level of crawler engineer. The next shared learning path is for rookies or peers who will soon learn Python web crawlers.

Learning web crawler can be divided into three steps, if you are a god, please go around directly, crab ~

The first step, when you first touch the Python web crawler, you must first go through the most basic knowledge of Python, such as variables, strings, lists, dictionaries, tuples, manipulating sentences, grammar, etc., so that you won't feel vague when doing a case. In addition, you also need to understand the basic principles of web requests, web page structure (such as HTML, XML) and so on.

The second step, watch the video or find a professional web crawler book (such as writing web crawlers in Python), follow other people's crawler code, follow other people's code, understand each line of code, be sure to start to practice, so that you can learn faster and understand more.

Many times we are so happy that we feel that we have this meeting, and then we are unwilling to start. In fact, the truth is full of loopholes than when we started. It is best to keep tapping the code every day to find some feeling.

Development of things advocate the choice of Python3, as the protection of Python2 will be suspended by 2020, Python3 will definitely be the mainstream in the future.

IDE can choose pycharm, sublime or jupyter, etc., and the editor recommends the use of pychram. Because it is very friendly, it is somewhat similar to eclipse in java, which is very intelligent.

In terms of browsers, learn to use Chrome or FireFox browsers to check elements and use them to grab packages.

In addition, at this stage, you also need to understand the reptile things and libraries in the mainstream, such as urllib, requests, re, bs4, xpath, json, etc., some commonly used reptile structures such as scrapy must be grasped, this structure is still quite simple, beginners may find it difficult to resist, but when the amount of data captured is very large, you will find her beautiful.

The third step, you now have the idea of reptiles, it is time to start by yourself, you can independently design the crawler system, find more websites to do exercises. Grasp the requirements of the crawling strategies and methods of static web pages and dynamic web pages, understand the web pages loaded by JS, understand selenium+PhantomJS imitating browsers, and know how to deal with json pattern data.

If the web page is a POST request, you should know to pass in data parameters, and this kind of web page is generally loaded dynamically, so grasp the package method. If you want to improve the power of the crawler, you have to consider the use of multithreading, multi-process is still cooperative, or distributed operation.

This is the answer to the question about how to get started with Python web crawler. I hope the above content can be of some help to you. If you still have a lot of doubts to be solved, you can follow the industry information channel to learn more about it.

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