Building a nested progress bar with postfixes in tqdm

Question

I know how to build nested progress bar using tqdm.

from tqdm import trange 
from time import sleep
for i in trange(10, desc='1st loop'):
    for j in trange(5, desc='2nd loop', leave=False):
        for k in trange(100, desc='3nd loop'): sleep(0.01)

I also know how to add postfixes and description to a bar

from tqdm import trange 
from random import random, randint 
from time import sleep 
with trange(100) as t: 
    for i in t: 
         t.set_description('GEN %i' % i) 
         t.set_postfix(loss=random(),  gen=randint(1,999), str='h', lst=[1, 2])   
         sleep(0.1)

Question

How can I add description and postfixes to nested progress bars in tqdm? I would like to add independent postfixes to each nested bar.

Answer 1

Nesting works fine:

from tqdm import trange
from time import sleep

n_epochs, n_steps = 5, 100
with trange(1, n_epochs + 1, desc="All epochs") as epochs:
    for epoch in epochs:
        with trange(1, n_steps + 1, desc="Epoch {}/{}".format(epoch, n_epochs)) as steps:
            for step in steps:
                epochs.set_postfix(foo=epoch * n_steps + step)
                steps.set_postfix(bar="hello {}".format(step), baz=1 / step)
                sleep(0.01)

Edit

The output looks like this when running (in this example, we're in the middle of the 3rd epoch):

Epoch 1/5: 100%|██████| 100/100 [00:01<00:00, 81.41it/s, bar=hello 100, baz=0.01]
Epoch 2/5: 100%|██████| 100/100 [00:01<00:00, 81.04it/s, bar=hello 100, baz=0.01]
All epochs:  40%|█████████▍              | 2/5 [00:03<00:04,  1.26s/it, foo=349]
Epoch 3/5:  48%|███▎  | 48/100 [00:00<00:00, 79.08it/s, bar=hello 49, baz=0.0204]

And it looks like this at the end:

Epoch 1/5: 100%|██████| 100/100 [00:01<00:00, 81.41it/s, bar=hello 100, baz=0.01]
Epoch 2/5: 100%|██████| 100/100 [00:01<00:00, 81.04it/s, bar=hello 100, baz=0.01]
Epoch 3/5: 100%|██████| 100/100 [00:01<00:00, 80.23it/s, bar=hello 100, baz=0.01]
Epoch 4/5: 100%|██████| 100/100 [00:01<00:00, 80.27it/s, bar=hello 100, baz=0.01]
Epoch 5/5: 100%|██████| 100/100 [00:01<00:00, 80.20it/s, bar=hello 100, baz=0.01]
All epochs: 100%|█████████████████████████| 5/5 [00:06<00:00,  1.24s/it, foo=600]