The various packages python

Because of the need to address different needs, therefore, python prepared a rich set of modules. As long as import can be used, simple and efficient.

>>> collection module

　　>> Named tuples (namedtuple), you can pass parameters to specify the location of 11, after the assignment, you can call alone can be used to store coordinate location

　　>> Queue (queue), go to Advanced

>> deque

>> ordered dictionary (OrderDict), remember the order of addition of dictionary elements

>> defaultdict () The default value is set in the key of the dictionary

The number of occurrences >> counter, single-character string of statistics

Module >>> time: time taken, formatted output time,

>>> random is an interesting module, all with random probability relevant places, can be used. (Below: get Code)

>>> os: can realize interact with the operating system.

　　os.mkdir ( 'xxx filename'): Create a folder

　　os.path.exists ( 'folder path'): determining whether there is a folder

　　The os.path.isfile ( 'file path'): determining whether the file exists

　　os.rmdir ( 'folder path'): You can only delete empty folders

　　os.path.dirname (__ file__): Gets the path of the current file

　　the os.path.join ( 'folder path 1', 'folder path 2'): stitching path

　　the os.listdir ( 'folder path'): Displays the current folder and all file names

　　the os.chdir ( 'folder path'): switching all of the current directory

　　os.getcwd (): Get all the current directory

　　os.path.getsize ( 'file path'): Get File Size, in bytes

>>> sys interact with the program

　　sys.path.append('文件夹路径'):可以将指定文件夹路径添加到程序环境变量中,
>>>json不同语言编写的程序之间,进行数据传递的工具

　　因为语言之间设计的不同,他能转换的数据类型是有限的.

　　序列化:将字符串转换成其他数据类型

　　dumps:转换后,可以写入文件,也可以直接赋值给变量.进行传递

　　dump:转换后,需要以wb或rb的形式写入文件

　　反序列化:将其他数据类型转换成字符串

　　loads:将变量名或文件中读取的内容反序列化

　　load:将文件中读取的内容反序列化

>>>pikle是python内部专用的其他语言无法识别,可以转换python中的所有数据类型

　　dump,load,dumps,loads.操作方法和json一样.好处之一就是可以保存python对象

>>>subprocess:子进程序,可以调用cmd命令行,执行命令,并返回结果

while True:
    cmd = input('cmd>>>:').strip()
    import subprocess
    obj = subprocess.Popen(cmd,shell=True,stdout=subprocess.PIPE,stderr=subprocess.PIPE)
    # print(obj)
    print('正确命令返回的结果stdout',obj.stdout.read().decode('gbk'))
    print('错误命令返回的提示信息stderr',obj.stderr.read().decode('gbk'))

The various packages python

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