Loader.__len__ is not a pure function

[dpaleka]

Counterintuitively, calling len() on a ffcv.loader.Loader instance modifies its internal state:

ffcv/ffcv/loader/loader.py

Lines 253 to 258 in bfd9b3d

	def __len__(self):
	next_order = self.next_traversal_order()
	if self.drop_last:
	return len(next_order) // self.batch_size
	else:
	return int(np.ceil(len(next_order) / self.batch_size))

This causes the bug in #140 when paired with OrderOption.QUASI_RANDOM.
I suppose the culprit is this line:

ffcv/ffcv/traversal_order/quasi_random.py

Line 24 in bfd9b3d

random.shuffle(page_to_samples_array[page_ix, :page_size])

[GuillaumeLeclerc]

Thanks @dpaleka It should be an easy fix :)

[GuillaumeLeclerc]

Thanks for the report, it will be in the next release