How to use os.mkdir and os.makedirs in python

1 The use of os.mkdir

• os.mkdir(dir_name): used to create a new folder, when you want to create a new folder When the folder already exists, an error will be reported: FileExistsError: [Errno 17] File exists:

Therefore, when we usually create a new folder, It will be used together with os.path.exists(), as follows:

1. Determine whether a folder exists. If it does not exist, create it. If it already exists, create it. If it exists, skip it:

dir_name = "./images"
if not os.path.exists(dir_name):
    os.mkdir(dir_name)

2 The use of os.makedirs

os.makedirs(dir_name2, exist_ok=True): The function is the same as os.mkdir. Create a new folder, but it is more convenient to use and has more functions

• os.makedirs: multiple folders can be created recursively

• os.makedirs: When the exist_ok parameter is set to True, it can automatically determine when the folder already exists and not create it.

is as follows, which is a recursive new directory: images/imgs2

dir_name2 = "./images2/imgs2"
os.makedirs(dir_name2, exist_ok=True)

3 View the attribute methods starting with certain letters in a module

• Use dir(module_name) First check all methods and attributes of the module

• Combined list generation and if statement to determine the methods and attributes starting with a certain letter

For example, the following is to view the properties of all color space conversions in the opencv module

import cv2

cvtCOLORS = [color for color in dir(cv2) if color.startswith("COLOR_")]
print(cvtCOLORS)

Print out all the color space related properties in opencv.

Supplement: The difference and usage between os.mkdir() and os.makedirs() in Python

os.makedir(path) and os.makedirs(path) I will use hadoop files at work today Synchronize to the server disk. Since there are many file categories and directories, you need to determine whether they exist when migrating files. There are two methods os.mkdir(path) and os.makedirs(path)

First of all, os.mkdir(path ), its function is to create directories level by level. The premise is that the previous directory already exists. If it does not exist, an exception will be reported, which is more troublesome, but it exists for its own reason. When your directory is dynamically created based on the file name When you do it, you will find that although it is cumbersome, it is very safe. It will not create double or multi-layer error paths because of your temporary hand shaking.

import os
 
os.mkdir('d:\hello')    #  正常
os.mkdir('d:\hello\hi') #  正常
 
#  如果d:\hello目录不存在
#  则os.mkdir('d:\hello\hi')执行失败

Then os.makedirs(path) , you can guess the difference just from the writing method. It can create multi-level directories at one time. Even if the intermediate directory does not exist, it can be created normally (for you). It is scary to think about it. What if you write a wrong word in the intermediate directory? .........

 import os
 
os.makedirs('d:\hello')    #  正常
os.makedirs('d:\hello\hi') #  正常
 
#  如果d:\hello目录不存在
#  则os.makedirs('d:\hello\hi')  #  仍然正常

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