tqdm: simple visual progress for python

illustrate

The main purpose of this article is to get started quickly, not to parse the source code.

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- tqdm: simple visual progress for python

1. Application scenarios

There are many application scenarios of the progress bar, but I have been studying the content of the CV direction recently, so the progress bar is mainly used to visualize the process of network training.

2. Library installation

tqdm is a third-party library of python, which can quickly and easily realize the visual display of the progress bar.

The installation method is very simple, Windows can run the following command in the cmd command line window:

pip install tqdm

3. Quick overview of the method

tqdm object creation

The method we mainly use here is the method with the same name as the library, ie tqdm.

from tqdm import tqdm

The function of this method is to create a "progress bar object", which needs to pass in a parameter, which is usually an iterable object. for example:

# 1. range函数
bar = tqdm(range(10))
# 2. 列表
bar = tqdm(['a',1,2,3,4])
# 3. 字典
bar = tqdm({
    
    'k':1,'b':2})  # 不过迭代访问时访问的是key
# 4. torch里面的数据加载器（这也是我需要的）
train_bar = tqdm(train_loader)

After the tqdm object is created, we no longer use the iterable object just now when iterating, but directly use the tqdm object , as shown below:

# 导包
from tqdm import tqdm
# 1. 创建进度条对象
bar = tqdm(range(10))
# 2. 迭代访问
for i in bar:
	print(i)

The result of running the above code is:

insert image description here

Important methods of tqdm

This object has a very important method, that is tqdm.desc, this method can realize the content of custom display progress bar.

The code demonstrated above just displays the progress bar. If we want the content format of the progress bar to be : 你好，这是我的进度条{}/{}, the contents of the two square brackets are the current index and the total number respectively.

Then you can modify the code like this:

# 导包
from tqdm import tqdm
import  time
# 1. 创建进度条对象
bar = tqdm(range(10))
# 2. 显示
for e in bar:
    bar.desc = '你好，这是我的进度条 {}/{}'.format(e+1, 10)

The result of the operation is as follows:

insert image description here

It is worth reminding again: the iterative object must use the tqdm object, otherwise it will have no effect .

important point

Since the above code is very short, it will run in a very short time, so we can't see the transformation of the progress bar. At this time, we can use the time.sleep(0.5)method to increase the delay.

4. Case

Here is a complete demo code for you:

# 导包
from tqdm import tqdm
import  time
# 1. 创建进度条对象
bar = tqdm(range(10))
# 3. 访问
for e in bar:
    bar.desc = 'hello,test {}/{}'.format(e+1, 10)
    time.sleep(0.5)

The result is shown in the gif image below: (I recorded the screen using debugging)

insert image description here

5. Summary

In fact, there are many progress bar display libraries, and the progress bars implemented by many libraries are very cool, you can try it yourself.

But generally speaking, a simple progress bar like tqdm is enough for us to use when writing scripts.