Python Basics Built-In Modules Explained

I.os

import os
 
# 1. Get the absolute path to the current script.
"""
abs_path = (__file__)
print(abs_path)
"""
 
# 2. Get the parent directory of the current file
"""
base_path = ( (trails) ）
print(base_path)
"""
 
# 3. Path splicing
"""
p1 = (base_path, 'xx')
print(p1)
p2 = (base_path, 'xx', 'oo', '')
print(p2)
"""
 
# 4. determining whether a path exists
"""
exists = (p1)
print(exists)
"""
 
# 5. Creating folders
"""
(trails)
"""
"""
path = (base_path, 'xx', 'oo', 'uuuu')
if not (path):
    (path)
"""
 
# 6. is it a folder
"""
file_path = (base_path, 'xx', 'oo', '')
is_dir = (file_path)
print(is_dir) # False
folder_path = (base_path, 'xx', 'oo', 'uuuu')
is_dir = (folder_path)
print(is_dir) # True
"""
 
# 7. Delete a file or folder
"""
("File path")
"""
"""
path = (base_path, 'xx')
(path)
"""

listdir to see all files in the directory
walk, see all files in the directory (including descendant files)

import os
 
"""
data = ("/Users/hqss/PycharmProjects/luffyCourse/day14/commons")
print(data)
# ['', '__init__.py', '', '__pycache__', '', 'tencent']
"""
 
"""
To iterate over all files in a folder, e.g., to iterate over all mp4 files in a folder
"""
 
data = ("/Users/hqss/Documents/Video Tutorials/Luffy Python/mp4")
for path, folder_list, file_list in data:
    for file_name in file_list:
        file_abs_path = (path, file_name)
        ext = file_abs_path.rsplit(".",1)[-1]
        if ext == "mp4":
            print(file_abs_path)

II. Shutil

import shutil
 
# 1. Deletion of folders
"""
path = (base_path, 'xx')
(path)
"""
 
# 2. Copy the folder
"""
("/Users/hqss/Desktop/Graph/csdn/","/Users/hqss/PycharmProjects/CodeRepository/files")
"""
 
# 3. Copying files
"""
("/Users/hqss/Desktop/Diagram/csdn/WX20201123-112406@","/Users/hqss/PycharmProjects/CodeRepository/")
("/Users/hqss/Desktop/Diagram/csdn/WX20201123-112406@","/Users/hqss/PycharmProjects/CodeRepository/")
"""
 
# 4. File or folder renaming
"""
("/Users/hqss/PycharmProjects/CodeRepository/","/Users/hqss/PycharmProjects/CodeRepository/")
("/Users/hqss/PycharmProjects/CodeRepository/files","/Users/hqss/PycharmProjects/CodeRepository/images")
"""
 
# 5. compressed files
"""
# base_name, compressed tarball file
# format, the format of the compression, e.g. "zip", "tar", "gztar", "bztar", or "xztar".
# root_dir, path to the folder to be compressed
"""
# shutil.make_archive(base_name=r'datafile',format='zip',root_dir=r'files')
 
 
# 6. Unzip the file
"""
# filename, the zip file to be unzipped
# extract_dir, the path of the extracted file
# format, compressed file format
"""
# shutil.unpack_archive(filename=r'', extract_dir=r'xxxxxx/xo', format='zip')

III. sys

import sys
 
# 1. Getting the interpreter version
"""
print()
print(sys.version_info)
print(sys.version_info.major, sys.version_info.minor, sys.version_info.micro)
"""
 
# 2. Importing module paths
"""
print()
"""

argv, the parameter passed after the python interpreter when executing a script

import sys
 
print()
 
 
# [
# '/Users/hqss/PycharmProjects/luffyCourse/day14/2.Accepting arguments for executing the script.py'
# ]
 
# [
# "2. Accept parameters for executing the script.py"
# ]
 
# ['2. Accept arguments for executing the script.py', '127', '999', '666', 'wupeiqi']
 
# For example, please implement a tool to download images.
 
def download_image(url):
    print("Download image", url)
 
 
def run():
    # Accept parameters passed in by the user
    url_list = [1:]
    for url in url_list:
        download_image(url)
 
 
if __name__ == '__main__':
    run()

IV. Random

import random
 
# 1. Get a random integer in the range
v = (10, 20)
print(v)
 
# 2. Get a range of random decimals
v = (1, 10)
print(v)
 
# 3. A randomly selected element
v = ([11, 22, 33, 44, 55])
print(v)
 
# 4. Random selection of multiple elements
v = ([11, 22, 33, 44, 55], 3)
print(v)
 
# 5.
data = [1, 2, 3, 4, 5, 6, 7, 8, 9]
(data)
print(data)

V. Hashlib

import hashlib
 
hash_object = hashlib.md5()
hash_object.update("Wu Pei Qi".encode('utf-8'))
result = hash_object.hexdigest()
print(result)

import hashlib
 
hash_object = hashlib.md5("iajfsdunjaksdjfasdfasdf".encode('utf-8'))
hash_object.update("Wu Pei Qi".encode('utf-8'))
result = hash_object.hexdigest()
print(result)

VI. Configparser

See the address, Python reads ini configuration files using configparser, for details.https:///article/

VII. xml

See the address, python custom parsing of simple xml format files, for details.https:///article/

VIII. json

The json module, an internal python module, can convert python data format to json format, and can also convert json format data to python data format.

json format, a data format (essentially a string, commonly used for network data transfer)

# The format of data types in Python
data = [
    {"id": 1, "name": "Wu Pei Qi", "age": 18},
    {"id": 2, "name": "alex", "age": 18},
    ('wupeiqi',123),
]
 
# JSON format
value = '[{"id": 1, "name": "Wu Pei Qi", "age": 18}, {"id": 2, "name": "alex", "age": 18},["wupeiqi",123]]'

core functionality

The role of json format

Cross-language data transfer, for example:
System A is developed in Python and has list types, dictionary types, etc.
System B is developed in Java and has types of arrays, maps, etc.

The underlying data type format is different for each language.

In order to facilitate the transfer of data, we agreed on a format: json format, each language is to convert their own data types to json format, but also can be converted to their own data types in json format.

Interconversion of Python data types to json format:

Data type -> json , generally known as: serialized

import json
 
data = [
    {"id": 1, "name": "Wah Ching Shui", "age": 18},
    {"id": 2, "name": "alex", "age": 18},
]
 
res = (data)
print(res) # '[{"id": 1, "name": "\u6b66\u6c9b\u9f50", "age": 18}, {"id": 2, "name": "alex", "age": 18}]'
 
res = (data, ensure_ascii=False)
print(res) # '[{"id": 1, "name": "Wah Ching Sui Shang", "age": 18}, {"id": 2, "name": "alex", "age": 18}]''

json format -> data type, generally known as: deserialized

import json
 
data_string = '[{"id": 1, "name": "Wah Ching Shui", "age": 18}, {"id": 2, "name": "alex", "age": 18}]'
 
data_list = (data_string)
 
print(data_list)

Type Requirements

The python data type conversion to json format has requirements on the data type, which is only supported by default:

 +-------------------+---------------+
    | Python            | JSON          |
    +===================+===============+
    | dict              | object        |
    +-------------------+---------------+
    | list, tuple       | array         |
    +-------------------+---------------+
    | str               | string        |
    +-------------------+---------------+
    | int, float        | number        |
    +-------------------+---------------+
    | True              | true          |
    +-------------------+---------------+
    | False             | false         |
    +-------------------+---------------+
    | None              | null          |
    +-------------------+---------------+
 
 
data = [
    {"id": 1, "name": "Wu Pei Qi", "age": 18},
    {"id": 2, "name": "alex", "age": 18},
]

Other types need to be customized if they want supportJSONEncodercan only be realized

import json
from decimal import Decimal
from datetime import datetime
 
data = [
    {"id": 1, "name": "Wu Pei Qi", "age": 18, 'size': Decimal("18.99"), 'ctime': ()},
    {"id": 2, "name": "alex", "age": 18, 'size': Decimal("9.99"), 'ctime': ()},
]
 
 
class MyJSONEncoder():
    def default(self, o):
        if type(o) == Decimal:
            return str(o)
        elif type(o) == datetime:
            return ("%Y-%M-%d")
        return super().default(o)
 
 
res = (data, cls=MyJSONEncoder)
print(res)

Other Functions

commonly used in json modules:

, serialized to generate a string.

, hair serialization generates python data types.

, serialize data and write to file (not commonly used)

import json
 
data = [
    {"id": 1, "name": "Wu Pei Qi", "age": 18},
    {"id": 2, "name": "alex", "age": 18},
]
 
file_object = open('', mode='w', encoding='utf-8')
 
(data, file_object)
 
file_object.close()

, reads data from a file and deserializes it to a python data type (not commonly used)

import json
 
file_object = open('', mode='r', encoding='utf-8')
 
data = (file_object)
print(data)
 
file_object.close()

IX. TIME

import time
 
# Get current timestamp (since 1970-1-1 00:00)
v1 = ()
print(v1)
 
# Time zones
v2 = 
 
# Stop for n seconds before executing subsequent code.
(5)

X. Datetime

Time in the usual development process is generally thought to exist in the following three formats:

datetime

from datetime import datetime, timezone, timedelta
 
v1 = ()  # Current local time
print(v1)
 
tz = timezone(timedelta(hours=7))  # Current time in Sector 7 East
v2 = (tz)
print(v2)
 
v3 = ()  # Current UTC time
print(v3)

from datetime import datetime, timedelta
 
v1 = ()
print(v1)
 
# Adding and subtracting time
v2 = v1 + timedelta(days=140, minutes=5)
print(v2)
 
# datetime type + timedelta type

from datetime import datetime, timezone, timedelta
 
v1 = ()
print(v1)
 
v2 = ()  # Current UTC time
print(v2)
 
# Subtract between datetimes to calculate intervals (can't add)
data = v1 - v2
print(,  / 60 / 60, )
 
# datetime type - datetime type
# datetime types Compare datetime types

string (computer science)

# Time in string format ---> converted to datetime format time
text = "2021-11-11"
v1 = (text,'%Y-%m-%d') # %Y year, %m, month, %d, day.
print(v1)

# datetime format ----> convert to string format
v1 = ()
val = ("%Y-%m-%d %H:%M:%S")
print(val)

timestamp

# Timestamp format --> convert to datetime format
ctime = () # 11213245345.123
v1 = (ctime)
print(v1)

# datetime format ---> convert to timestamp format
v1 = ()
val = ()
print(val)

Supplement:

UTC/GMT: Universal Time
Local time: the time in the local time zone.

There are two modules in Python for time processing, time and datetime.

This is the end of the summary of the 10 built-in modules commonly used in Python, and you are welcome to criticize and correct them!

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