When we import a module: import XXX, by default the python parser will search the current directory, installed built-in modules and third-party modules. The search path is stored in the path of the sys module:

import sys
sys.path

output:

['d:\\program\\anaconda3\\envs\\learn_py36\\python36.zip',
 'd:\\program\\anaconda3\\envs\\learn_py36\\DLLs',
 'd:\\program\\anaconda3\\envs\\learn_py36\\lib',
 'd:\\program\\anaconda3\\envs\\learn_py36',
 '',
 'd:\\program\\anaconda3\\envs\\learn_py36\\lib\\site-packages',
 'd:\\program\\anaconda3\\envs\\learn_py36\\lib\\site-packages\\win32',
 'd:\\program\\anaconda3\\envs\\learn_py36\\lib\\site-packages\\win32\\lib',
 'd:\\program\\anaconda3\\envs\\learn_py36\\lib\\site-packages\\Pythonwin',
 'd:\\program\\anaconda3\\envs\\learn_py36\\lib\\site-packages\\IPython\\extensions',
 'C:\\Users\\DELL\\.ipython']

can see that the result is a list, that is, we use import to import the module, in the list of these contents to search. So sys.path.append() brackets fill in the path to import the module, and then you can import the module using the import module.

os.path. Exists () :
OS operating system (operating system), Python OS module encapsulates the system files and file paths. The
os.path module is mainly used for obtaining file properties. Exists means “exists”, so os.path. Exists () is used to determine the existence of a file in parentheses. For all files in the system and their paths, you can determine.
returns: True or False

OS. Path. The join () : </ strong>
OS. The path. The join (” father “, “subset”)
the returned result is:
father set subset \ ‘
meaning to add “subset” to “father” after the path.

os.makedirs() :
create folders under the current path: subset
can also write absolute paths:
os.makedirs(‘C:\Users\DELL\Desktop\ subset)
create folders named as subsets on the Desktop.