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2026-07-13 13:32:23 +08:00

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# Copyright (C) CVAT.ai Corporation
#
# SPDX-License-Identifier: MIT
from __future__ import annotations
from collections.abc import Callable, Iterable, Mapping, Sequence
from typing import Generic, TypeVar
import attrs
import numpy as np
_K = TypeVar("_K")
@attrs.define
class _BaggedCounter(Generic[_K]):
# Stores items with count = k in a single "bag". Bags are stored in the ascending order
bags: dict[
int,
dict[_K, None],
# dict is used instead of a set to preserve item order. It's also more performant
]
@staticmethod
def from_dict(item_counts: Mapping[_K, int]) -> _BaggedCounter:
return _BaggedCounter.from_counts(item_counts, item_count=item_counts.__getitem__)
@staticmethod
def from_counts(items: Sequence[_K], item_count: Callable[[_K], int]) -> _BaggedCounter:
bags = {}
for item in items:
count = item_count(item)
bags.setdefault(count, dict())[item] = None
return _BaggedCounter(bags=bags)
def __attrs_post_init__(self):
self._sort_bags()
def _sort_bags(self):
self.bags = dict(sorted(self.bags.items(), key=lambda e: e[0]))
def shuffle(self, *, rng: np.random.Generator | None):
if not rng:
rng = np.random.default_rng()
for count, bag in self.bags.items():
items = list(bag.items())
rng.shuffle(items)
self.bags[count] = dict(items)
def use_item(self, item: _K, *, count: int | None = None, bag: dict | None = None):
if count is not None:
if bag is None:
bag = self.bags[count]
elif count is None and bag is None:
count, bag = next((c, b) for c, b in self.bags.items() if item in b)
else:
raise AssertionError("'bag' can only be used together with 'count'")
bag.pop(item)
if not bag:
self.bags.pop(count)
next_bag = self.bags.get(count + 1)
if next_bag is None:
next_bag = {}
self.bags[count + 1] = next_bag
self._sort_bags() # the new bag can be added in the wrong position if there were gaps
next_bag[item] = None
def __iter__(self) -> Iterable[tuple[int, _K, dict]]:
for count, bag in self.bags.items(): # bags must be ordered
for item in bag:
yield (count, item, bag)
def select_next_least_used(self, count: int) -> Sequence[_K]:
pick = [None] * count
pick_original_use_counts = [(None, None)] * count
for i, (use_count, item, bag) in zip(range(count), self):
pick[i] = item
pick_original_use_counts[i] = (use_count, bag)
for item, (use_count, bag) in zip(pick, pick_original_use_counts):
self.use_item(item, count=use_count, bag=bag)
return pick
class HoneypotFrameSelector(Generic[_K]):
def __init__(
self,
validation_frame_counts: Mapping[_K, int],
*,
rng: np.random.Generator | None = None,
):
if not rng:
rng = np.random.default_rng()
self.rng = rng
self._counter = _BaggedCounter.from_dict(validation_frame_counts)
self._counter.shuffle(rng=rng)
def select_next_frames(self, count: int) -> Sequence[_K]:
# This approach guarantees that:
# - every GT frame is used
# - GT frames are used uniformly (at most min count + 1)
# - GT frames are not repeated in jobs
# - honeypot sets are different in jobs
# - honeypot sets are random
# if possible (if the job and GT counts allow this).
# Picks must be reproducible for a given rng state.
"""
Selects 'count' least used items randomly, without repetition
"""
return self._counter.select_next_least_used(count)