foreword
As we all know, Python is the easiest programming language to use. If you have a certain foundation, you can learn Python crawlers in minutes. For zero-based learners, Python crawlers are relatively simple. You only need to learn the programming language Python first, and then write a few lines of code to be a crawler.
What is the use of learning Python crawlers?
With the advent of the era of big data, the World Wide Web has become the carrier of a large amount of information, how to effectively extract and use this information has become a huge challenge. Based on this demand, crawler technology came into being and quickly developed into a mature technology. Based on the data collection needs of many Internet companies, the demand for crawler engineers is increasing day by day.
Learning crawlers, you can customize a search engine, and you can have a deeper understanding of the working principle of search engine data collection. In the era of big data, to conduct data analysis, we must first have a data source, and learning crawlers can allow us to obtain more data sources, and these data sources can be collected according to our purpose, removing a lot of irrelevant data. For many SEO practitioners, learning crawlers can provide a deeper understanding of the working principles of search engine crawlers, so that they can perform better search engine optimization. From the perspective of employment, crawler engineers are currently in short supply, and their salaries are generally high. Therefore, it is very beneficial for employment to master this technology in depth.
Next, let's see how novices learn reptiles.
Phase 1 : Mainly to learn the basics of Python, to the extent that you can basically master Python.
Phase 2 : Understand the implementation principles and technologies of crawlers, including the implementation principles of crawlers, the detailed process of crawling webpages, the classification of webpages in general crawlers, general crawler-related website files, anti-crawler coping strategies, why Python is chosen as a crawler, etc. At this stage, it is necessary to learn how crawlers crawl web pages, and to understand some problems that arise during the crawling process.
Stage 3 : Learn the principles of webpage requests, including the process of browsing webpages, the principles of HTTP network requests, and the HTTP packet capture tool Fiddler.
Phase 4 : Introduced two libraries for crawling web page data: urllib and requests. First learn the basic usage of the urllib library, including using urllib to transfer data, adding specific headers, setting proxy servers, timeout settings, and common network exceptions, and then learn about the more user-friendly requests library, preferably combined with a case of Baidu Tieba. Learn how to use the urllib library to scrape web data. At this stage, everyone should be able to master the use of the two libraries proficiently, and use them repeatedly for more practice.
Stage 5 : The main learning is several technologies for parsing web page data, including regular expressions, XPath, Beautiful Soup and JSONPath, and in-depth study of the basic use of Python modules or libraries that encapsulate these technologies, including re modules, lxml library, bs4 library, and json module, it is best to combine the case of Tencent’s social recruitment website to understand how to use the re module, lxml library, and bs4 library to parse web page data respectively, so as to better distinguish the differences between these technologies.
Stage 6 : It mainly explains the concurrent downloading, including multi-threaded crawler process analysis, using the queue module to realize multi-threaded crawlers, and coroutines to realize concurrent crawling. It is best to use single-threaded, multi-threaded, and The three technologies of the coroutine obtain web page data and analyze the performance of the three.
Stage 7 : Learning around capturing dynamic content, including dynamic web page introduction, overview of selenium and PhantomJS, installation and configuration of selenium and PhantomJS, basic use of selenium and PhantomJS, preferably combined with a simulated Douban website login case, learning in the project How to apply selenium and PhantomJS technology.
Stage 8 : Learning mainly for image recognition and text processing, including the download and installation of the Tesseract engine, pytesseract and PIL libraries, processing text in standardized formats, processing verification codes, etc. It is best to combine small programs that recognize local verification code pictures , learn how to recognize captchas in images with pytesseract.
Stage 9 : Mainly learn to store crawler data, including introduction to data storage, introduction to MongoDB database, storage to database using PyMongo library, etc. It is best to combine the case of Douban Movies to learn how to crawl, parse, and store from the website step by step Movie information.
Stage 10 : Mainly conduct preliminary learning on the crawler framework Scrapy, including the introduction of common crawler frameworks, the structure of the Scrapy framework, the operation process, installation, basic operations, etc.
Phase 11 : First learn the Scrapy terminal and core components. To understand the startup and use of the Scrapy terminal, it is best to consolidate it through an example, and then learn some core components of the Scrapy framework in detail, including Spiders, Item Pipeline and Settings. Finally, it is best to combine the case of the Douyu App crawler to understand how Use the Scrapy framework to grab the data of the mobile app.
Stage 12 : Continue to learn the knowledge of CrawlSpider, a crawler that automatically crawls webpages, including the first understanding of crawler CrawlSpider, the working principle of CrawlSpider class, determining crawling rules through Rule class and extracting links through LinkExtractor class.
The 13th stage : Learning around the Scrapy-Redis distributed crawler, including the complete architecture, operation process, main components, basic usage of Scrapy-Redis, and how to build a Scrapy-Redis development environment, etc., it is best to use the case of Baidu Encyclopedia these knowledge points.
The above is the basic process of learning Python crawlers. Do you think it is difficult? In fact, as long as you follow each of the above learning stages, step by step, and learn Python crawlers in a down-to-earth manner, I believe that everyone will be able to easily get started with crawlers soon.
Finally, I would like to share with you a piece of information about learning Python. Python is a very good programming language with high salary and good employment prospects . It can be applied to crawlers, web development, data analysis, artificial intelligence and other fields. Even if you don't want to go to work, you can use Python to do part-time jobs at home (such as crawling data needed by customers, quantifying transactions, writing programs, etc.).
If you are interested in Python and want to get a higher salary by learning Python, then the following set of Python learning materials must be useful to you!
Materials include: Python installation package + activation code, Python web development, Python crawler, Python data analysis, artificial intelligence, machine learning and other learning tutorials. Even beginners with 0 basics can understand and understand. Follow the tutorial and take you to learn Python systematically from zero basics!
1. Introduction to Python
The following content is the basic knowledge necessary for all application directions of Python. If you want to do crawlers, data analysis or artificial intelligence, you must learn them first. Anything tall is built on primitive foundations. With a solid foundation, the road ahead will be more stable.All materials are free at the end of the article！！！
Include:
Computer Basics
python basics
Python introductory video 600 episodes:
Watching the zero-based learning video is the fastest and most effective way to learn. Following the teacher's ideas in the video, it is still very easy to get started from the basics to the in-depth.
2. Python crawler
As a popular direction, reptiles are a good choice whether it is a part-time job or as an auxiliary skill to improve work efficiency.
Relevant content can be collected through crawler technology, analyzed and deleted to get the information we really need.
This information collection, analysis and integration work can be applied in a wide range of fields. Whether it is life services, travel, financial investment, product market demand of various manufacturing industries, etc., crawler technology can be used to obtain more accurate and effective information. use.
Python crawler video material
3. Data analysis
According to the report "Digital Transformation of China's Economy: Talents and Employment" released by the School of Economics and Management of Tsinghua University, the gap in data analysis talents is expected to reach 2.3 million in 2025.
With such a big talent gap, data analysis is like a vast blue ocean! A starting salary of 10K is really commonplace.
4. Database and ETL data warehouse
Enterprises need to regularly transfer cold data from the business database and store it in a warehouse dedicated to storing historical data. Each department can provide unified data services based on its own business characteristics. This warehouse is a data warehouse.
The traditional data warehouse integration processing architecture is ETL, using the capabilities of the ETL platform, E = extract data from the source database, L = clean the data (data that does not conform to the rules), transform (different dimension and different granularity of the table according to business needs) calculation of different business rules), T = load the processed tables to the data warehouse incrementally, in full, and at different times.
5. Machine Learning
Machine learning is to learn part of the computer data, and then predict and judge other data.
At its core, machine learning is "using algorithms to parse data, learn from it, and then make decisions or predictions about new data." That is to say, a computer uses the obtained data to obtain a certain model, and then uses this model to make predictions. This process is somewhat similar to the human learning process. For example, people can predict new problems after obtaining certain experience.
Machine Learning Materials:
6. Advanced Python
From basic grammatical content, to a lot of in-depth advanced knowledge points, to understand programming language design, after learning here, you basically understand all the knowledge points from python entry to advanced.
At this point, you can basically meet the employment requirements of the company. If you still don’t know where to find interview materials and resume templates, I have also compiled a copy for you. It can really be said to be a systematic learning route for nanny and .
But learning programming is not achieved overnight, but requires long-term persistence and training. In organizing this learning route, I hope to make progress together with everyone, and I can review some technical points myself. Whether you are a novice in programming or an experienced programmer who needs to be advanced, I believe that everyone can gain something from it.
It can be achieved overnight, but requires long-term persistence and training. In organizing this learning route, I hope to make progress together with everyone, and I can review some technical points myself. Whether you are a novice in programming or an experienced programmer who needs to be advanced, I believe that everyone can gain something from it.
Data collection
This full version of the full set of Python learning materials has been uploaded to the official CSDN. If you need it, you can click the CSDN official certification WeChat card below to get it for free ↓↓↓ [Guaranteed 100% free]
Good article recommended
Understand the prospect of python: https://blog.csdn.net/SpringJavaMyBatis/article/details/127194835
Learn about python's part-time sideline: https://blog.csdn.net/SpringJavaMyBatis/article/details/127196603