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Python crawler how to learn to get started quickly, in view of this problem, this article introduces the corresponding analysis and solution in detail, hoping to help more partners who want to solve this problem to find a more simple and easy way.

Learning crawlers is a gradual process, as a zero-basic rookie, generally can be divided into three stages, the first stage is an introduction, master the necessary basic knowledge, the second stage is imitation, follow other people's crawler code, understand each line of code, the third stage is do-it-yourself, this stage you begin to have your own ideas, you can independently design the crawler system.

The techniques involved in crawlers include, but are not limited to, proficiency in a programming language (take Python as an example) * * HTML knowledge, basic knowledge of HTTP/HTTPS protocols, regular expressions, database knowledge, the use of common packet crawling tools, crawler frameworks, large-scale crawlers, distributed concepts, message queues, commonly used data structures and algorithms, caching, and even machine learning applications. Large-scale systems are supported by a lot of technology.

Crawler is only to obtain data, analysis, mining these data is the value, so it can also be extended to data analysis, data mining and other fields to make decisions for enterprises, so as a crawler engineer, it is promising.

So do you have to learn all the above before you can start writing about crawlers? Of course not, learning is a lifetime thing, as long as you can write Python code, just start crawling, like learning to drive, as long as you can start, hit the road, of course, writing code is much safer than driving.

For starter crawlers, it is not necessary to learn regular expressions. You can learn them when you really need them. For example, after you crawl the data back, you need to clean the data. When you find that it is impossible to deal with it using conventional string manipulation methods, you can try to understand regular expressions, which can often get twice the result with half the effort. Python's re module can be used to process regular expressions.

Data cleaning will eventually require persistent storage, you can use file storage, such as CSV files, you can also use database storage, simply use sqlite, professional point to use MySQL, or distributed document database MongoDB, these databases are very Python-friendly, with off-the-shelf library support. Python operates the MySQL database to connect to the database through Python.

About practice

There are many online crawler tutorials, the principle is roughly the same, but for a different website to crawl, you can follow the online tutorials to learn to simulate login to a website, simulate clocking in and so on, climb Douban movies, books and so on. Through constant practice, from meeting problems to solving problems, the harvest of reading is incomparable.

Reptile common library

Urllib, urlib2 (urllib in Python) python built-in network request library

Urllib3: thread-safe HTTP Network request Library

Requests: the most widely used network request library, compatible with py2 and py3

Grequests: asynchronous requests

Operation analysis library of BeautifulSoup:HTML and XML

Lxml: another way to deal with HTML and XML

Tornado: asynchronous Network Framework

Gevent: asynchronous Network Framework

Scrapy: the most popular crawler framework

Pyspider: crawler framework

Convert xmltodict:xml to dictionary

Pyquery: operate HTML like jQuery

Jieba: participle

SQLAlchemy:ORM framework

Celery: message queuing

Rq: simple message queue

Python-goose: extracting text from HTML

Books

"schematic HTTP"

Authoritative Guide to HTTP

Computer Networks: a Top-Down approach

"Writing web crawlers with Python"

"Python Network data Collection"

"proficient in regular expressions"

"getting started with Python"

"write your own web crawler."

"Crypto101"

"graphical cryptographic technology"

The answer to the question about how Python crawler can learn to get started quickly is shared here. 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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