tqdm Helps You Save Time

Made by Mike_Zhang

Unfold Python Topics $\triangledown$

Intro

「时间就是金钱，效率就是生命」

在编写和运行Python程序时，我们常常想知道运行完成的预计时间，以便更好地安排时间，如：

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def foo():
    # do something in black box...

for i in range(100):
    foo()

在这种情况下，我们可以使用Python的tqdm库来显示进度条，以便更好地了解程序的运行情况，如：

  • 记录已经完成的任务数量/任务时间
  • 预计完成时间
  • 记录运行速度
  • …

tqdm Usage

1. Installation

https://github.com/tqdm/tqdm?tab=readme-ov-file#installation

1.1 via pip

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pip install tqdm

https://pypi.org/project/tqdm/

1.2 via conda

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conda install -c conda-forge tqdm

2. Using

2.1 Automatically update

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from tqdm import tqdm
import time
# for i in range(100): # just wrap your iterable range(100) with tqdm()
for i in tqdm(range(100), desc="Loading..."):
    time.sleep(0.1)

Output:

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Loading...:  20%|██        | 20/100 [00:02<00:08,  9.33it/s]

2.2 Manually update

If you want to update the progress bar manually, you can use the following code:

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from tqdm import tqdm
import time
pbar = tqdm(total=100) # create a progress bar
for i in range(10):
    time.sleep(0.1)
    pbar.update(10) # update the progress bar
pbar.close() # close the progress bar

Output:

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50%|█████     | 50/100 [00:00<00:00, 95.48it/s]

2.3 Advanced Usage

2.3.1 Set description and postfix

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from tqdm import tqdm
import time
pbar = tqdm(total=100)
for i in range(10):
    pbar.set_description(f"Processing {i}")
    pbar.set_postfix({"loss": 0.1})
    time.sleep(0.1)
    pbar.update(1)
pbar.close()

Output:

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Processing 9:  10%|█         | 10/100 [00:01<00:09,  9.28it/s, loss=0.1]

2.3.2 Set width of the progress bar

To fit the progress bar in the terminal, you can set the width of the progress bar:

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from tqdm import tqdm
import time
for i in tqdm(range(100), desc="Loading...", ncols=100):
    time.sleep(0.1)

ncols=100:

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Loading...: 100%|█████████████████████████████████████████████████| 100/100 [00:10<00:00,  9.48it/s]

ncols=80:

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Loading...: 100%|█████████████████████████████| 100/100 [00:10<00:00,  9.46it/s]

ncols=60:

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Loading...: 100%|█████████| 100/100 [00:10<00:00,  9.46it/s]

2.3.3 Printing during the progress bar

If you use print() during the progress bar, the progress bar will be interrupted, like:

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from tqdm import tqdm
import time
pbar = tqdm(total=5, ncols=80)
for i in range(5):
    print(f"\nProcessing {i}")
    time.sleep(0.1)
    pbar.update(1)
pbar.close()

Output:

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 0%|                                                     | 0/5 [00:00<?, ?it/s]
Processing 0
 20%|█████████                                    | 1/5 [00:00<00:00,  9.52it/s]
Processing 1
 40%|██████████████████                           | 2/5 [00:00<00:00,  9.51it/s]
Processing 2
 60%|███████████████████████████                  | 3/5 [00:00<00:00,  9.51it/s]
Processing 3
 80%|████████████████████████████████████         | 4/5 [00:00<00:00,  9.61it/s]
Processing 4
100%|█████████████████████████████████████████████| 5/5 [00:00<00:00,  9.57it/s]

To avoid this, you can use pbar.write() instead of print():

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from tqdm import tqdm
import time
pbar = tqdm(total=5, ncols=80)
for i in range(5):
    # print(f"\nProcessing {i}")
    pbar.write(f"Processing {i}")
    time.sleep(0.1)
    pbar.update(1)
pbar.close()

Output:

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Processing 0                                                                    
Processing 1                                                                    
Processing 2                                                                    
Processing 3                                                                    
Processing 4                                                                    
100%|█████████████████████████████████████████████| 5/5 [00:00<00:00,  9.47it/s]

where the progress bar will always be displayed at the bottom of the terminal and the text will be displayed above the progress bar.

2.3.4 Color, position and nested progress bars

If you want to display nested progress bars, you can use the following code:

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from tqdm import tqdm
import time
for i in tqdm(range(2), desc="[Split]", ncols=80, leave=False, colour="green"):
    for j in tqdm(range(5), desc="[Epoch]", ncols=80, leave=False, colour="blue"):
        for k in tqdm(range(10), desc="[Batch]", ncols=80, leave=False, colour="red"):
            time.sleep(0.1)

Output:


Where leave=False arranges the position of the progress bar, and colour sets the color of the progress bar.

You can find more parameters and examples in the official documentation here.

References

“tqdm/tqdm: A Fast, Extensible Progress Bar for Python and CLI” GitHub, 2025. https://github.com/tqdm/tqdm.

Outro

最后，你知道tqdm是什么的缩写吗？代表了什么意思呢？请在下方留言，分享你的看法。

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Made by Mike_Zhang




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tqdm Helps You Save Time
https://ultrafish.io/post/tqdm-helps-you-save-time/
Author
Mike_Zhang
Posted on
January 10, 2025
Licensed under