当前位置：网站首页>Day14 function module

Day14 function module

2022-07-23 15:58:00 【Bruce_ Liuxiaowei】

day14 modular

master Python How to use common modules in .

Custom module （ package ）
Third-party module
Built-in module 【1/2】

1. Custom module

1.1 Modules and packages

import hashlib


def encrypt(data):
    """  Data encryption  """
    hash_object = hashlib.md5()
    hash_object.update(data.encode('utf-8'))
    return hash_object.hexdigest()


user = input(" Please enter a user name ：")
pwd = input(" Please input a password ：")
md5_password = encrypt(pwd)

message = " user name ：{}, password ：{}".format(user, md5_password)
print(message)

When developing simple programs , Use one py The file can be done , If the program is relatively large , Need some 10w Line code , At this time, in order to , The code structure is clear , Split functions into different ones according to certain rules py In file , When you use it, you can import it . in addition , When other projects also need some modules of this project , You can also take the module directly to use , Increase reusability .

If you split according to a certain rule , Found split to commons.py Too many functions in , You can also split again through folders , for example ：

├── commons
│   ├── convert.py
│   ├── page.py
│   └── utils.py
└── run.py

stay Python The general title of documents and documents in （ Many developers are also called modules in their daily development ）

One py file , modular （module）.
Multiple py File folder , package （package）.

Be careful ： In the bag （ Folder ） One of the default contents is empty __init__.py The file of , Generally used to describe the information of the current package （ When importing the following modules , It will also load automatically ）.

py2 There has to be , If the package is not imported, it will fail .
py3 not essential .

1.2 Import

After defining a module or package , If you want to use the functions defined therein , You must first import , Then you can use .

Import , In fact, it is to load modules or packages into memory , Go to the memory to get it later .

About the path of derivation as time ：

stay Python Some paths are set internally by default , When importing a module or package , Will find specific paths one by one in the specified order .

import sys
print(sys.path)


[
	 	' Directory of currently executing script ',
		'/Users/liuxiaowei/PycharmProjects/ Lu Feiquan stack /day14', '/Users/liuxiaowei/PycharmProjects/ Lu Feiquan stack ', 								'/Applications/PyCharm.app/Contents/plugins/python/helpers/pycharm_display', 																		'/Library/Frameworks/Python.framework/Versions/3.9/lib/python39.zip', 																					'/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9', 																							'/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/lib-dynload', 										    					'/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages', 																'/Applications/PyCharm.app/Contents/plugins/python/helpers/pycharm_matplotlib_backend'
]

Want to import arbitrary modules and packages , Must be written in the following path , To be found .

It can also be automatically and manually in sys.path Add the specified path to the , Then you can import , for example ：

import sys
sys.path.append(" route A")

import xxxxx  #  Import path A Under a xxxxx.py file

1. When you write the module name later , Never have the same name as built-in and third-party （ Novices are prone to make mistakes ）.

2. Project execution files are usually in the root directory of the project , If the execution file is nested in the memory directory , You need to manually sys.path Add path to .

3.pycharm By default, the project directory will be added to sys.path in

pycharm By default, the project directory will be added to sys.path in

About how to import ：

Import essentially loads the contents of a file into memory first , Then go to the memory and get it for use . And in the Python Common import methods in development include 2 Class mode , There are many situations in each way .

The first category ：import xxxx（ In development , It is usually used for importing sys.path A... In the catalog py file ）

Module level

├── commons
│   ├── __init__.py
│   ├── convert.py
│   ├── page.py
│   ├── tencent
│   │   ├── __init__.py
│   │   ├── sms.py
│   │   └── wechat.py
│   └── utils.py
├── many.py
└── run.py

Package level

├── commons
│   ├── __init__.py
│   ├── convert.py
│   ├── page.py
│   └── utils.py
├── third
│   ├── __init__.py
│   ├── ali
│   │   └── oss.py
│   └── tencent
│       ├── __init__.py
│       ├── __pycache__
│       ├── sms.py
│       └── wechat.py
└── run.p

The second category ：from xxx import xxx 【 Commonly used 】, It is generally applicable to multi-level nesting and importing a member of a module .

Member level
```
├── commons
│   ├── __init__.py
│   ├── convert.py
│   ├── page.py
│   └── utils.py
├── many.py
└── run.py
```
Tips ： be based on from Patterns can also support from many import *, namely ： Import all members in a module （ May have duplicate names , So use less ）.

Module level

├── commons
│   ├── __init__.py
│   ├── convert.py
│   ├── page.py
│   └── utils.py
├── many.py
└── run.py

Package level

├── commons
│   ├── __init__.py
│   ├── convert.py
│   ├── page.py
│   ├── tencent
│   │   ├── __init__.py
│   │   ├── sms.py
│   │   └── wechat.py
│   └── utils.py
├── many.py
└── run.py

1.3 Relative Import

When importing the module , about from xx import xx This model , It also supports relative Import . for example ：

Bear in mind , Relative import can only be used in py In file （ namely ： Nested in a file py Documents can only be used , The project root directory cannot be used ）.

1.4 Import alias

If you import member / modular / package Have duplicate names , Then the later import will overwrite the previous import , To avoid this happening ,Python Support rename , namely ：

from xxx.xxx import xx as xo
import x1.x2 as pg

besides , With as The existence of , Give Way import xx.xxx.xxxx.xxx When calling execution , It's going to be easier （ Not commonly used , Understanding can ）.

original

import commons.page
v1 = commons.page.pagination()

Now?

import commons.page as pg

v1 = pg.pagination()

1.5 Master file

Execute one py When you file
```
__name__ = "__main__"
```
Import a py When you file
```
__name__ = " Module name "
```

Master file , In fact, it is the entry file in the program execution , for example ：

├── commons
│   ├── __init__.py
│   ├── convert.py
│   ├── page.py
│   ├── tencent
│   │   ├── __init__.py
│   │   ├── sms.py
│   │   └── wechat.py
│   └── utils.py
├── many.py
└── run.py

We usually execute run.py To run the program , Other py Files are all function codes . When we execute a file , Inside the document __name__ The value of the variable is __main__, therefore , The master file is often seen ：

import many
from commons import page
from commons import utils


def start():
    v1 = many.show()
    v2 = page.pagination()
    v3 = utils.encrypt()


if __name__ == '__main__':
    start()

Only when you run this script as a master file start Function to execute , When imported, it will not be executed .

Summary

The difference between modules and packages
Two ways to import modules ：
```
import xx
from xxx import xxx
```
Relative Import , Package name is required .
Module duplicate names can be obtained by as Take the alias .
perform py When you file , Inside __name__=="__main__", When importing a module , Imported modules __name__=" Module name "
In project development , Generally, it will be written in the main file main （ Main file mark , Not absolutely , Because other files may sometimes exist during development and debugging main）.

MAC System , namely ：Python Of the installation path bin Under the table of contents

2. Third-party module

Python The modules provided internally are limited , So in the process of development , Third party modules are often used .

Third party modules must be installed before they can be used , Here are some common 3 How to install third-party modules in .

Actually , The behavior of using third-party modules is to use others to write and open source py Code , So you can use it yourself , There is no need to build wheels again ....

2.1 pip（ The most commonly used ）

This is a Python The most commonly used way to install third-party modules .

pip It is actually a third-party module package management tool , Default installation Python The interpreter will be installed automatically , default directory ：

MAC System , namely ：Python Of the installation path bin Under the table of contents 
	/Library/Frameworks/Python.framework/Versions/3.9/bin/pip3
	/Library/Frameworks/Python.framework/Versions/3.9/bin/pip3.9
	
Windows System , namely ：Python Of the installation path scripts Under the table of contents 
	C:\Python39\Scripts\pip3.exe
	C:\Python39\Scripts\pip3.9.exe

Tips ： For the convenience of running at the terminal pip Management tools , We will also add its path to the system environment variable .

pip3 install  Module name

If something written on your computer is not found pip, You can also install it manually ：

download get-pip.py file , To any directory

 Address ：https://bootstrap.pypa.io/get-pip.py

Open the terminal and enter the directory , use Python The interpreter runs the downloaded get-pip.py The file was installed immediately .

Use pip It is also very easy to install third-party modules , You only need to execute on your own terminal ：pip install Module name that will do

The latest version is installed by default , If you want to specify the version ：

pip3 install  Module name == edition 

 for example ：
pip3 install django==2.2

2.1.1 pip to update

The yellow font above suggests ： Currently on my computer pip yes 20.2.3 edition , The latest is 20.3.3 edition , If you want to upgrade to the latest version , You can execute the command prompted by him at the terminal ：

/Library/Frameworks/Python.framework/Versions/3.9/bin/python3.9 -m pip install --upgrade pip

Be careful ： Execute according to the prompt command of your computer , Don't use my prompt command here .

2.1.2 Douban source

pip The default is to https://pypi.org Go to download the third-party module （ In essence, it is written by others py Code ）, The speed of foreign websites will be relatively slow , In order to speed up the use of domestic sources of watercress .

One time use

pip3.9 install  Module name   -i  https://pypi.douban.com/simple/

Permanent use

To configure

#  Execute the following command at the terminal 
pip3.9 config set global.index-url https://pypi.douban.com/simple/

#  After execution , Prompt: the Douban source is written in my local file , We'll go through it later pip When installing third-party modules , The Douban source will be used by default .
#  You can also open the file and modify the source address directly in the future .
Writing to /Users/wupeiqi/.config/pip/pip.conf

Use
```
pip3.9 install  Module name 
```

At the end , There are other sources to choose from （ Douban is widely used ）.

 Alibaba cloud ：http://mirrors.aliyun.com/pypi/simple/
 University of science and technology of China ：https://pypi.mirrors.ustc.edu.cn/simple/ 
 Tsinghua University ：https://pypi.tuna.tsinghua.edu.cn/simple/
 University of science and technology of China ：http://pypi.mirrors.ustc.edu.cn/simple/

2.2 Source code

If the module to be installed is pypi.org Does not exist in the or Unable to pass due to special reasons pip install When installing , You can download the source code directly , Then install based on the source code , for example ：

download requests Source code （ Compressed package zip、tar、tar.gz） And extract the .
```
 Download address ：https://pypi.org/project/requests/#files
```
Entry directory

Execute compile and install commands

python3 setup.py build
python3 setup.py install

2.3 wheel

wheel yes Python A file format of the third-party module package , We can also be based on wheel Install some third-party modules .

install wheel Format support , such pip When installing the third-party module , You can deal with wheel The format of the file .
```
pip3.9 install wheel
```
Download third-party packages （wheel Format ）, for example ：https://pypi.org/project/requests/#files

Enter download directory , Based on pip Direct installation

No matter how you install the third-party module , The default module installation path is ：

Max System ：
	/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages
Windows System ：
	C:\Python39\Lib\site-packages\

remind ： This catalog is in sys.path in , So we can import the downloaded third-party packages directly into the code .

3. Built-in module （ One ）

Python There are many built-in modules , We have also contacted many related modules , Next, let's do some summary and introduction .

There are many built-in modules & There are also many functions in the module , We can't pay attention to the overall situation and explain it to you , Here I will sort out the most commonly used ones for project development to explain .

3.1 os

import os

# 1.  Get the absolute path of the current script 
""" abs_path = os.path.abspath(__file__) print(abs_path) """

# 2.  Get the parent directory of the current file 
""" base_path = os.path.dirname( os.path.dirname( route ) ） print(base_path) """

# 3.  Path splicing 
""" p1 = os.path.join(base_path, 'xx') print(p1) p2 = os.path.join(base_path, 'xx', 'oo', 'a1.png') print(p2) """

# 4.  Determine if the path exists 
""" exists = os.path.exists(p1) print(exists) """

# 5.  Create folder 
""" os.makedirs( route ) """
""" path = os.path.join(base_path, 'xx', 'oo', 'uuuu') if not os.path.exists(path): os.makedirs(path) """

# 6.  Is it a folder 
""" file_path = os.path.join(base_path, 'xx', 'oo', 'uuuu.png') is_dir = os.path.isdir(file_path) print(is_dir) # False folder_path = os.path.join(base_path, 'xx', 'oo', 'uuuu') is_dir = os.path.isdir(folder_path) print(is_dir) # True """

# 7.  Delete files or folders 
""" os.remove(" File path ") """
""" path = os.path.join(base_path, 'xx') shutil.rmtree(path) """

listdir, View all files in the directory
walk, View all files in the directory （ Documents including descendants

import os

""" data = os.listdir("/Users/wupeiqi/PycharmProjects/luffyCourse/day14/commons") print(data) # ['convert.py', '__init__.py', 'page.py', '__pycache__', 'utils.py', 'tencent'] """

"""  To traverse all the files in a folder , for example ： Traverse all the folders mp4 file  """

data = os.walk("/Users/wupeiqi/Documents/ Video tutorial / Monkey D Luffy Python/mp4")
for path, folder_list, file_list in data:
    for file_name in file_list:
        file_abs_path = os.path.join(path, file_name)
        ext = file_abs_path.rsplit(".",1)[-1]
        if ext == "mp4":
            print(file_abs_path)

3.2 shutil

import shutil

# 1.  Delete folder 
""" path = os.path.join(base_path, 'xx') shutil.rmtree(path) """

# 2.  Copy folder 
""" shutil.copytree("/Users/wupeiqi/Desktop/ chart /csdn/","/Users/wupeiqi/PycharmProjects/CodeRepository/files") """

# 3. Copy files 
""" shutil.copy("/Users/wupeiqi/Desktop/ chart /csdn/[email protected]","/Users/wupeiqi/PycharmProjects/CodeRepository/") shutil.copy("/Users/wupeiqi/Desktop/ chart /csdn/[email protected]","/Users/wupeiqi/PycharmProjects/CodeRepository/x.png") """

# 4. File or folder rename 
""" shutil.move("/Users/wupeiqi/PycharmProjects/CodeRepository/x.png","/Users/wupeiqi/PycharmProjects/CodeRepository/xxxx.png") shutil.move("/Users/wupeiqi/PycharmProjects/CodeRepository/files","/Users/wupeiqi/PycharmProjects/CodeRepository/images") """

# 5.  Compressed files 
""" # base_name, Compressed package file  # format, Compressed format , for example ："zip", "tar", "gztar", "bztar", or "xztar". # root_dir, Folder path to compress  """
# shutil.make_archive(base_name=r'datafile',format='zip',root_dir=r'files')


# 6.  Unzip the file 
""" # filename, Zip file to unzip  # extract_dir, Decompression path  # format, Compressed file format  """
# shutil.unpack_archive(filename=r'datafile.zip', extract_dir=r'xxxxxx/xo', format='zip')

3.3 sys

import sys

# 1.  Get the interpreter version 
""" print(sys.version) print(sys.version_info) print(sys.version_info.major, sys.version_info.minor, sys.version_info.micro) """

# 2.  Import module path 
""" print(sys.path) """

argv, When executing a script ,python Parameters passed in after the interpreter

import sys

print(sys.argv)


# [
# '/Users/wupeiqi/PycharmProjects/luffyCourse/day14/2. Accept the parameters for executing the script .py'
# ]

# [
# "2. Accept the parameters for executing the script .py"
# ]

# ['2. Accept the parameters for executing the script .py', '127', '999', '666', 'wupeiqi']

#  for example , Please implement a tool for downloading pictures .

def download_image(url):
    print(" Download the pictures ", url)


def run():
    #  Accept the parameters passed in by the user 
    url_list = sys.argv[1:]
    for url in url_list:
        download_image(url)


if __name__ == '__main__':
    run()

3.4 random

import random

# 1.  Get random integers in the range 
v = random.randint(10, 20)
print(v)

# 2.  Get random decimals in the range 
v = random.uniform(1, 10)
print(v)

# 3.  Randomly extract an element 
v = random.choice([11, 22, 33, 44, 55])
print(v)

# 4.  Randomly extract multiple elements 
v = random.sample([11, 22, 33, 44, 55], 3)
print(v)

# 5.  Out of order 
data = [1, 2, 3, 4, 5, 6, 7, 8, 9]
random.shuffle(data)
print(data)

3.5 hashlib

import hashlib

hash_object = hashlib.md5()
hash_object.update(" Liu Xiaowei ".encode('utf-8'))
result = hash_object.hexdigest()
print(result)

import hashlib

hash_object = hashlib.md5("iajfsdunjaksdjfasdfasdf".encode('utf-8'))
hash_object.update(" Liu Xiaowei ".encode('utf-8'))
result = hash_object.hexdigest()
print(result)

3.6 configparser

see ：day09

3.7 xml