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This article mainly introduces the Python yaml file reading method is what the relevant knowledge, the content is detailed and easy to understand, the operation is simple and fast, with a certain reference value, I believe that everyone after reading this Python yaml file reading method is what the article will have a harvest, let's take a look.

The Application scene and format of yaml File introduction to the Application scenario of yaml File

Yaml is also similar to json and txt, which belong to a text format. In our actual work, yaml files are often used as service period profiles. For example, if there is information that is defined and will not be modified, we can import the data into our service by defining a yaml file and then reading such a file.

Because yaml files are generally used as configuration files, they are rarely modified. Therefore, in this chapter, we only learn how to read yaml files.

Format of the yaml file

= = first of all, you need to know that yaml is not a markup language. Like json, the purpose of yaml is to serialize data. The content format is a key-value pair, but the style displayed is different from that of the key-value pair of the dict data type. The content format is humanized and easy to read. = = yaml file format is suffixed with .yaml.

Note: YAML has a small quirk. The starting line of all YAML files should be -. This is part of the YAML format, indicating the beginning of a file. >

The format of the YAML syntax is as follows:

1. Case sensitivity

2. Use indentation to represent hierarchical relationships

3. The number of indented spaces is not important, as long as the elements at the same level are aligned to the left, usually starting with two indented spaces

4. Tab key tab indentation is not supported, only space indentation is supported.

5. Indent a space after the character, such as colon, comma, short crossbar (-), etc.

6. "-" indicates the YAML format, the beginning of a file, which is used to separate files

7. "#" indicates comments (yaml files have line comments only)

There are three data structures supported by YAML.

Object: a collection of key-value pairs, also known as mapping / hashes / dictionary (dictionary)

Array: a group of values arranged in order, also known as sequence / list

Scalar (scalars): a single, non-separable value

These three data structures are described in detail below:

The values in yaml have the following basic types:

String

Shaping

Floating point type

Boolean type

Null

time

Date

An example of the yaml file content format is as follows:

# Note # 1-1, dictionary key: value username: xiaoming # colon followed by a space password: 123456info: configuration # Chinese-not recommended There may be garbled code # 1-2, dictionary nesting NAME_PSW: name:xiaoming password:123456# 2-1, list format-10-20-3 NAME_PSW-2-2, list nesting-10-20-100-20 name:xiaoming password:123456# 3-1, dictionary nesting in list-10-20-name: tom password:123456# 4-1, dictionary set list name: TOMinfo:-10-20-3 "5-1, quotation marks if there are English letters or Chinese characters. Without quotation marks is also a string info: "HELLO word" # quotation marks can not add # 5-2, what with quotation marks: if there are vulgar characters\ nwithout quotation marks the original character style output if the special character effect is displayed: add double quotation marks info: "HELLO\ nwoord" # 6-1, citing a data can be used in many places Use variable # & variable name to define variable # * variable name reference variable name: & a tomname1: * a # 7-1, can multiple YAML be written together, there are dictionaries and lists, plus delimiters-10-20-30---name: sq# 8-1, yamL files can have YAMLDATA: conf.yaml third-party package-pyyaml

Installation of pyyaml: pip install PyYAML [if installation fails, refer to the package and Modules section on how to install a third-party package]

Import of pyyaml: import pyyaml

The method of reading yaml file

The usage is as follows:

File = open (yaml_file,'r') daya = yaml.load (file.read ()) file.close

Returns the dictionary type (example):

{'name':' Tony Stark''age':' 52''sex':' man'} yaml file read demo case

Create a test.yaml file with the following contents:

Name: Tony Stark # string quotation marks can not be added [the indentation here uses the tab key, so if you copy and paste directly, you will get an error when running the following script, remember to change it to a space] invention:-Iron Man Armor-Arc reactor-Ultronteammate:-Steven Rogers-Thor Odinson-Natasha Romanoff-Bruce Banner-Clint Bartonapprentice: Peter Parker wife: Pepper Boz father: Howard Stark

Create a test_yaml.py file and read the test.yaml file:

# coding:utf-8import yamldef read (path): with open (path,'r') as file: data = file.read () result = yaml.load (data) # result = yaml.load (data, Loader=yaml.FullLoader) return resultif _ _ name__ = ='_ main__': result = read ('test.yaml') print (result)

An error occurred during execution here: TypeError: load () missing 1 required positional argument: 'Loader'. As shown below:

This is because the usage of yaml.load (file) was abandoned after YAML version 5.1, because it felt very unsafe. After version 5.1, the need to specify Loader was modified, and the load function became more secure by prohibiting the execution of arbitrary functions through the default loader (FullLoader). So we need to change result = yaml.load (data) to result = yaml.load (data, Loader=yaml.FullLoader).

Yaml.load (data, Loader=yaml.FullLoader) is not the only way to solve the TypeError.

The TypeError can be resolved by choosing one of the following three

Yaml.safe_load (file.read ()) yaml.load (file.read (), Loader=yaml.FullLoader) yaml.load (file.read (), Loader=yaml.CLoader)

The running results are as follows:

This is the end of the article on "what is the method of reading yaml files in Python?" Thank you for reading! I believe that everyone has a certain understanding of the knowledge of "what is the method of reading yaml files in Python". If you want to learn more knowledge, you are welcome to follow the industry information channel.

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