Generators example (1)

generators1.py

"""
Simple example shows usage of generators as coroutines accepting values from 
outside and yield processed values to caller.
"""
import re


def get_loss(regex='^[\d\w]+(\d.\d+).hdf5$'):
    """
    Checks if name of file with model weights matches regular expression and
    returns numerical value of loss.

    Otherwise, None is returned.
    """
    reg = re.compile(regex)
    while True:
        filename = yield
        match = reg.match(filename)
        result = None if match is None else float(match.group(1))
        yield result


def apply(gen, item):
    """Advance generator to next yield statement and sends value."""

    gen.send(None)
    result = gen.send(item)
    return result


def main():
    filenames = [
        'model.h5',
        'checkpoint',
        'weights_1.042.hdf5',
        'log.txt',
        'weights_bs128_0.984.hdf5',
        'weights_resnet_val_loss_0.209.hdf5'
    ]

    gen = get_loss()
    for filename in filenames:
        result = apply(gen, filename)
        if not result:
            continue
        print(result)


if __name__ == '__main__':
    main()