Change logging "print" function to "tqdm.write" so logging doesn't interfere with progress bars

Question

I have a simple question: How do I change the built-in Python logger’s print function to tqdm.write such that logging messages do not interfere with tqdm’s progress bars? Thanks!

Asked By: Guillochon

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Source

Answer 1

You need a custom logging handler:

import logging
import tqdm

class TqdmLoggingHandler(logging.Handler):
    def __init__(self, level=logging.NOTSET):
        super().__init__(level)

    def emit(self, record):
        try:
            msg = self.format(record)
            tqdm.tqdm.write(msg)
            self.flush()
        except Exception:
            self.handleError(record)

and then add this to the logging chain:

import time

log = logging.getLogger(__name__)
log.setLevel(logging.INFO)
log.addHandler(TqdmLoggingHandler())
for i in tqdm.tqdm(range(100)):
    if i == 50:
        log.info("Half-way there!")
    time.sleep(0.1)

Edit: Fixed a bug in the call to super TqdmLoggingHandler’s init method, that was pointed out by diligent reader @BlaineRogers in the comments. (If anyone wants to read further about this murky area of Python, I recommend https://fuhm.net/super-harmful/)

Answered By: RolKau

Answer 2

One easy solution, not so elegant, is convert the tqdm object to string. After that yo can log the message (or handle it as you want). The "format_dict" attribute may be useful as well:

from tqdm import tqdm
import time

#loop with progressbar:
it=tqdm(total=10)
for i in range(10):
    time.sleep(0.1)
    it.update(1)

it.close()
print("n","--"*10)

# Convert tdqm object last output to sting
str_bar_msg = str(it)
print(str_bar_msg)

# See attributes:
print(it.format_dict)

output:

100%|██████████| 10/10 [00:01<00:00,  8.99it/s]
 --------------------
100%|██████████| 10/10 [00:01<00:00,  8.98it/s]
{'n': 10, 'total': 10, 'elapsed': 1.1145293712615967, 'ncols': None, 'nrows': None, 'prefix': '', 'ascii': False, 'unit': 'it', 'unit_scale': False, 'rate': None, 'bar_format': None, 'postfix': None, 'unit_divisor': 1000, 'initial': 0, 'colour': None}

Best regards

Answered By: IgnacioT

Answer 3

the easiest way is change stream of StreamHandler object e.g.:

import logging
from tqdm import tqdm, trange
import time

log = logging.getLogger(__name__)
log.setLevel(logging.INFO)
handler = logging.StreamHandler()
handler.setStream(tqdm) # <-- important
handler = log.addHandler(handler)

for i in trange(100):
    if i == 50:
        log.info("Half-way there!")
    time.sleep(0.1)

Answered By: asiloisad

Answer 4

Based on RolKau’s answer above, simplified:

import logging
from tqdm import tqdm


class TqdmLoggingHandler(logging.StreamHandler):
    """Avoid tqdm progress bar interruption by logger's output to console"""
    # see logging.StreamHandler.eval method:
    # https://github.com/python/cpython/blob/d2e2534751fd675c4d5d3adc208bf4fc984da7bf/Lib/logging/__init__.py#L1082-L1091
    # and tqdm.write method:
    # https://github.com/tqdm/tqdm/blob/f86104a1f30c38e6f80bfd8fb16d5fcde1e7749f/tqdm/std.py#L614-L620

    def emit(self, record):
        try:
            msg = self.format(record)
            tqdm.write(msg, end=self.terminator)
        except RecursionError:
            raise
        except Exception:
            self.handleError(record)

Testing:

import time

log = logging.getLogger(__name__)
log.setLevel(logging.INFO)
log.addHandler(TqdmLoggingHandler())
#   ^-- Assumes this will be the unique handler emitting messages to sys.stdout.
#       If other handlers output to sys.stdout (without tqdm.write),
#       progress bar will be interrupted by those outputs

for i in tqdm(range(20)):
    log.info(f"Looping {i}")
    time.sleep(0.1)

Caveat: if you’re working in a Jupyter notebook, progress bar will be interrupted and AFAIK there’s no way to avoid it.

Answered By: Jean Monet

Answer 5

tqdm now has a built-in contextmanager for redirecting the logger:

import logging
from tqdm import trange
from tqdm.contrib.logging import logging_redirect_tqdm

LOG = logging.getLogger(__name__)

if __name__ == '__main__':
    logging.basicConfig(level=logging.INFO)
    with logging_redirect_tqdm():
        for i in trange(9):
            if i == 4:
                LOG.info("console logging redirected to `tqdm.write()`")
    # logging restored

Copied from tqdm documentation

Answered By: thomaskeefe

Answer 6

The new io handler is useful!

class TqdmToLogger(io.StringIO):
    logger = None
    level = None
    buf = ""

    def __init__(self, logger, level=None, mininterval=5):
        super(TqdmToLogger, self).__init__()
        self.logger = logger
        self.level = level or logging.INFO
        self.mininterval = mininterval
        self.last_time = 0

    def write(self, buf):
        self.buf = buf.strip("rnt ")

    def flush(self):
        if len(self.buf) > 0 and time.time() - self.last_time > self.mininterval:
            self.logger.log(self.level, self.buf)
            self.last_time = time.time()```

# before this line, you need to create logger with file handler
tqdm_out = TqdmToLogger(logger)
tbar = tqdm(sample, total=len(sample), file=tqdm_out)

logger.info("Model Inference.")
for it, batch_data in enumerate(tbar):
   pass

```

Answered By: choi

Change logging "print" function to "tqdm.write" so logging doesn't interfere with progress bars

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