Data crawling allows you to write less than 1000 lines of code! | Python regular expression, 1000 rows of python

Data crawling allows you to write less than 1000 lines of code! | Python regular expression, 1000 rows of python

BytesSpring flowers bloom, and it's a good season to go out and play!

When it comes to photography, do you have a picture? It is to process the relationship between people, scenes, and things in a limited space of a photo, and arrange the three in the best position on the screen to form a specific structure of the screen.

Is a photography black hole ...... Cannot breathe. jpg

In order to show specific protruding scenes, the school tried to useView boxAh, suddenly.

The original mountains, rivers, trees, grass, blue sky, white clouds, and other scenery, in the specific size and scope of the scene frame, took out a piece of the scenery I want.

Don't worry, you are not wrong. Today we are not going to learn photography technology and framing.

We will learn regular expressions based on Python to help you get more accurate results in crawler and search engine optimization!

Not afraid. We can understand it with the love of photography ~

What is a regular expression?

A regular expression is a logical formula for string operations. A "rule string" is formed by using predefined characters and combinations of these characters 」. This "rule string" is used to express a filtering logic for strings.

In retrospect, we use a defined shape, such as a circle, square, or diamond, to filter out the entire landscape and screen out the specific scenes we want to take, such as a tree or a cloud, is it clear at once?

Given a regular expression and another string, we can achieve the following goals:

1. Whether the given string matches the filtering logic of the regular expression (called "match ");
2. You can use a regular expression to obtain the desired part from the string;
3. You can also replace a string that meets a specific rule.

Why do we need to learn regular expressions?

You may have a rule string similar to the "scenario". What does it mean to me? What isSpecific application scenarios?

As far as crawler technology is concerned, for example, if we want to crawl a recruitment website, the traditional crawling method is a whole brain, you will get texts and data about various regions, cities, positions, salaries, requirements, and face Sutra. Then you can use the data processing method to filter your desired information.

If I only want the information "Beijing, product manager, and education industry for more than five years", I can use regular expressions to write crawler code to helpFast, efficient, and accurate positioningTo the information you want.

SimilarlyA simple method to achieve complex String ControlIt can also be applied to product reviews, public opinion, customer preferences, email information surveys, and other fields. In addition, there are search engines such as Google, Baidu, and sogou, if accurate matching and control are well performed, SEO promotion is optimized ~ Today's hot machine learning, the labels and syntaxes in it will also use regular expressions ~

Based on Python, let's learn it together!

Python is not much said. The Dark Horse of the 2017 program session. Select it to learn and adapt to the call of the times ~

This time, the school invited Jack, who once offered many courses on small Python projects in the school, to teach everyone how to learn the regular expression rules, from explanations to cases ~ Strive to get more accurate results with the least time and effort! Http://www.aibbt.com/a/18041.html

Of course, this courseYou need to get started with Python.At least know the basic data types and variables. The others will be brought to the bus by Jack ~