python using yaml format files

Install the PyYAML installer

YAML in the python language has the PyYAML installer, download it here:/pypi/PyYAML

For networked windows, you can go directly to the terminal with win+r cmd. pip install PyYAML

Configure the yaml file

Go to the directory of the corresponding python file and create the yaml file (omitted)

Created through programming software

Customize the file extension to .yaml

Write the contents of the yaml file

city: shanghai
time: 202210
successfully: 200
exception: 500

python reads yaml file

# Use utf-8 encoding
# -*- coding:utf-8 -*-
# Import yaml modules
import yaml
f = open('', 'r', encoding='utf-8')  # Read the yaml file, encoded in utf-8
cfg = ()  # Read all the files
d = (cfg, Loader=) # Use the load method to convert the contents of the read yaml file into a dictionary type
# yaml5.1 abandoned the use of (file) because it was unsafe, and after 5.1 changed the need to specify a loader to disable the execution of arbitrary functions through the default loader (FullLoader)
# Loader= Add this line of code and the alerts go away.
print(d)

The result is a dictionary type

{'city': 'shanghai', 'time': 202210, 'successfully': 200, 'exception': 500}

Comparison of yaml file and python code writing

Basic yaml syntax rules:
key-value pair
case sensitive
Using indentation to indicate hierarchical relationships
The Tab key is not allowed for indentation, only spaces are allowed.
The number of spaces in the indentation does not matter, as long as elements at the same level are left-aligned
# means comments, from this character to the end of the line, will be ignored by the parser, this is the same as python comments
There are three data structures supported by yaml:
Object: a collection of key-value pairs, also known as mapping / hashes / dictionary
Array: a set of values arranged in a sequence, also known as a sequence / list.
Pure quantities (scalars): single, non-redivisible values. String, Boolean, Integer, Float, Null, Time, Date

Dictionary Nested Dictionaries

# Dictionary nested dictionaries
#python code written as {'dd': 'city2:shanghai2 time2:2022102'}
#dd:
#  city2: shanghai2
#  time2: 2022102

Nested dictionaries in lists (or arrays, as they are called), a set of data in a dictionary

# Nested dictionaries in lists (or arrays)
#pythonThe code is written as[{'city2': 'shanghai2'}, {'time2': 2022102}, {'successfully': 200}]
#yaml write a list with a '-' sign in front of it
- city2: shanghai2
- time2: 2022102
- successfully: 200

Nested dictionaries in lists (or arrays), multiple sets of data in dictionaries

# Nested dictionaries in lists (or arrays)
The #python code is written as [{'city3': 'shanghai3', 'time3': 2022103}, {'city4': 'shanghai4', 'time4': 2022104}, {'city5': 'shanghai5', 'time5': 2022102}]
- city3: shanghai3
  time3: 2022103
- city4: shanghai4
  time4: 2022104
- city5: shanghai5
  time5: 2022102

Dictionary Nested Lists

# Dictionary nested lists
The #python code is written as {'color1': ['red', 1], 'color2': ['bule', 2], 'color3': ['black', 3]}
color1:
  - red
  - 1
color2:
  - bule
  - 2
color3:
  - black
  - 3

combine

# Combined use
#python code written as {'languages': ['Ruby', 'Perl', 'Python', 'java c++ shell'], 'websites': {'YAML': '', 'Ruby': '', 'Python': '', 'Perl': ''}, 'db': {' host': 'xxx', 'port': 3306, 'user': 'shanghai', 'password': 'xxx', 'db_name': 'china', 'db_type': 'mysql'}}
languages:
 - Ruby
 - Perl
 - Python
 - java c++ shell
websites:
 YAML: 
 Ruby: 
 Python: 
 Perl: 
db:
    host: xxx
    port: 3306
    user: shanghai
    password: xxx
    db_name: china
    db_type: mysql

Other types

#1, numerical values are expressed directly in the form of literal quantities
#number: 202210.010101 #{'number': 202210.010101}
#2. Boolean values are expressed in terms of true and false
#isSet: true #{'isSet': True}
#isSet1: false #{'isSet1': False}
#3. null is represented by ~
#parent: ~   #{'parent': None}
#4. Time is in ISO8601 format.
#time1: 2022-10-10t10:10:10.10-10:00  #{'time1': (2022, 10, 10, 10, 10, 10, 100000, tzinfo=((days=-1, seconds=50400)))}
##5. The date is expressed in year, month, and day in the composite iso8601 format.
#date: 2022-10-01  #{'date': (2022, 10, 1)}
#6, YAML allows the use of two exclamation points to force the conversion of a data type to a string str.
#int_to_str: !!str 123  #{'bool_to_str': '123'}
#bool_to_str: !!str true #{'bool_to_str': 'true'}

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