from fastai.vision import *
from fastai.gen_doc.nbdoc import *
from fastai.callbacks import *

show_doc(CSVLogger)

path = untar_data(URLs.MNIST_TINY)
data = ImageDataBunch.from_folder(path)
learn = Learner(data, simple_cnn((3, 16, 16, 2)), metrics=[accuracy, error_rate], callback_fns=[CSVLogger])

learn.fit(3)

learn.path.ls()

show_doc(CSVLogger.read_logged_file)

learn.csv_logger.read_logged_file()

# don't forget to remove the old file
if learn.csv_logger.path.exists(): os.remove(learn.csv_logger.path)

learn = Learner(data, simple_cnn((3, 16, 16, 2)), metrics=[accuracy, error_rate],
                callback_fns=[partial(CSVLogger, append=True)])

# stage-1
learn.fit(3)

# stage-2
learn.fit(3)

learn.csv_logger.read_logged_file()

show_doc(CSVLogger.on_train_begin)

show_doc(CSVLogger.on_epoch_end)

show_doc(CSVLogger.on_train_end)