Shaun ZhouandClaude Opus 5
345dee50da
此前 simclr.checkpoint 的语义是"有权重就跳过训练"，没有真正的续训： 中途停掉再启动只能从头再来，或者放弃已训的轮次。 - 新增 simclr_last.pth：骨架 + 投影头 + 优化器 + 调度器 + scaler + epoch + step， 与给下游用的 simclr_backbone.pth 并存，两者在同一时机落盘 - 新增 simclr.resume：载入完整状态从下一个 epoch 接着练。只恢复权重不恢复动量与 cosine 进度的话，续训时损失会先反弹一段 - resume 与 checkpoint 互斥（同时给直接报错）；拿只含骨架的 simclr_backbone.pth 去 resume 会给出可操作的报错，提示改用 checkpoint - 续训轮数已达计划值时不再训练，只打警告 Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
362 lines
14 KiB
Python
362 lines
14 KiB
Python
"""SimCLR 自监督：损失的数学性质 + 聚类脚本的 simclr 分支端到端。"""
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import sys
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import pytest
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torch = pytest.importorskip("torch")
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pytest.importorskip("PIL")
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import numpy as np # noqa: E402
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from PIL import Image # noqa: E402
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from engine.simclr import SimCLRTrainer, nt_xent_loss # noqa: E402
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from models.heads.projection import ProjectionHead # noqa: E402
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from models.registry import BACKBONES # noqa: E402
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def test_nt_xent_is_minimal_when_views_agree():
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"""两个视图完全一致且各样本互相正交时，损失应接近理论下界 log(2B−1) 的反面——
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即正样本对独占概率质量，损失趋近 0。"""
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z = torch.eye(4) # 4 个互相正交的样本
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aligned = nt_xent_loss(z, z.clone(), temperature=0.05)
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misaligned = nt_xent_loss(z, z.roll(1, dims=0), temperature=0.05)
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assert aligned < 0.1
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assert misaligned > aligned
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def test_nt_xent_upper_bound_at_chance_level():
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"""所有表征相同时无法区分正负样本，损失 = log(2B−1)。"""
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z = torch.ones(8, 16)
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loss = float(nt_xent_loss(z, z.clone(), temperature=0.2))
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assert loss == pytest.approx(float(torch.log(torch.tensor(2 * 8 - 1))), abs=1e-4)
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def test_nt_xent_is_symmetric_and_temperature_sensitive():
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torch.manual_seed(0)
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z1, z2 = torch.randn(6, 8), torch.randn(6, 8)
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assert float(nt_xent_loss(z1, z2, 0.2)) == pytest.approx(float(nt_xent_loss(z2, z1, 0.2)), abs=1e-5)
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# 温度越低，随机表征的损失越大（softmax 更尖，惩罚更重）
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assert nt_xent_loss(z1, z2, 0.05) > nt_xent_loss(z1, z2, 0.5)
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def test_nt_xent_gradient_pulls_positive_pair_together():
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torch.manual_seed(0)
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z1 = torch.randn(4, 8, requires_grad=True)
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z2 = torch.randn(4, 8, requires_grad=True)
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before = float(torch.nn.functional.cosine_similarity(z1, z2).mean().detach())
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optimizer = torch.optim.SGD([z1, z2], lr=1.0)
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for _ in range(20):
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optimizer.zero_grad()
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nt_xent_loss(z1, z2, 0.2).backward()
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optimizer.step()
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after = float(torch.nn.functional.cosine_similarity(z1, z2).mean().detach())
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assert after > before
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def test_projection_head_accepts_feature_map_and_vector():
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head = ProjectionHead(16, hidden_channels=32, out_channels=8)
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assert head(torch.randn(4, 16, 5, 5)).shape == (4, 8)
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assert head(torch.randn(4, 16)).shape == (4, 8)
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@pytest.fixture
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def tiny_image_dir(tmp_path):
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root = tmp_path / "imgs"
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root.mkdir()
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rng = np.random.default_rng(0)
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for i in range(8):
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Image.fromarray(rng.integers(0, 255, (40, 60, 3), dtype=np.uint8)).save(root / f"{i}.png")
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return root
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def test_simclr_trainer_runs_and_saves_backbone_only(tiny_image_dir, tmp_path):
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from torch.utils.data import DataLoader
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from datasets.unlabeled import UnlabeledImageDataset, unlabeled_collate
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dataset = UnlabeledImageDataset(
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tiny_image_dir,
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transforms=[{"name": "Resize", "size": [32, 32]}, {"name": "ToTensor"}],
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views=2,
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view_transforms=[{"name": "RandomResizedCrop", "size": [32, 32], "scale": [0.5, 1.0]}],
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)
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loader = DataLoader(dataset, batch_size=4, shuffle=True, drop_last=True, collate_fn=unlabeled_collate)
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backbone = BACKBONES.build({"name": "tiny_conv", "widths": [8, 16], "depths": [1, 1]})
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trainer = SimCLRTrainer(
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backbone,
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loader,
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{"epochs": 2, "amp": False, "log_interval": 100, "projection": {"hidden_channels": 16,
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"out_channels": 8}},
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torch.device("cpu"),
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tmp_path / "run",
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)
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path = trainer.fit()
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assert path.exists()
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state = torch.load(path, map_location="cpu", weights_only=False)
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# 只存骨架，不含投影头
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assert all("projector" not in key and "mlp" not in key for key in state["model"])
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backbone.load_state_dict(state["model"]) # 能被干净地加载回去
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def test_simclr_logs_metrics_to_swanlab(tiny_image_dir, tmp_path, monkeypatch):
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"""SwanLab 接线：按 step 记 loss/lr，按 epoch 记平均 loss、耗时与显存峰值，结束时收尾。"""
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from torch.utils.data import DataLoader
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import engine.simclr as simclr_mod
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from datasets.unlabeled import UnlabeledImageDataset, unlabeled_collate
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records: list[tuple[dict, int | None, str]] = []
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finished: list[bool] = []
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class StubLogger:
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def __init__(self, **kwargs):
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self.kwargs = kwargs
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def log(self, metrics, step=None, prefix=""):
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records.append((metrics, step, prefix))
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def finish(self):
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finished.append(True)
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monkeypatch.setattr(simclr_mod, "SwanLabLogger", StubLogger)
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dataset = UnlabeledImageDataset(
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tiny_image_dir,
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transforms=[{"name": "Resize", "size": [32, 32]}, {"name": "ToTensor"}],
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views=2,
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)
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loader = DataLoader(dataset, batch_size=4, shuffle=True, drop_last=True, collate_fn=unlabeled_collate)
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backbone = BACKBONES.build({"name": "tiny_conv", "widths": [8, 16], "depths": [1, 1]})
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trainer = simclr_mod.SimCLRTrainer(
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backbone,
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loader,
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{"epochs": 1, "amp": False, "log_interval": 1, "save_interval": 0,
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"projection": {"hidden_channels": 16, "out_channels": 8},
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"swanlab": {"enabled": True, "mode": "disabled"}},
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torch.device("cpu"),
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tmp_path / "run",
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full_config={"method": "simclr"},
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)
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trainer.fit()
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assert records, "没有任何指标被记录"
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assert all(prefix == "simclr/" for _, _, prefix in records)
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step_keys = {k for metrics, _, _ in records for k in metrics}
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assert {"loss", "loss_avg", "lr"} <= step_keys
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assert {"epoch", "epoch_loss", "epoch_seconds", "gpu_mem_peak_mb"} <= step_keys
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assert all(step is not None and step > 0 for _, step, _ in records)
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assert finished == [True] # fit() 结束时调用了 finish()
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# 完整 yaml 配置作为超参传给了 SwanLab
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assert trainer.visualizer.kwargs["config"] == {"method": "simclr"}
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assert trainer.visualizer.kwargs["mode"] == "disabled"
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def test_simclr_saves_intermediate_checkpoints(tiny_image_dir, tmp_path):
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"""中途落盘：跑到一半被打断也要能拿到权重（此前只在全部 epoch 跑完后才存）。"""
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from torch.utils.data import DataLoader
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from datasets.unlabeled import UnlabeledImageDataset, unlabeled_collate
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dataset = UnlabeledImageDataset(
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tiny_image_dir,
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transforms=[{"name": "Resize", "size": [32, 32]}, {"name": "ToTensor"}],
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views=2,
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)
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loader = DataLoader(dataset, batch_size=4, shuffle=True, drop_last=True, collate_fn=unlabeled_collate)
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backbone = BACKBONES.build({"name": "tiny_conv", "widths": [8, 16], "depths": [1, 1]})
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work_dir = tmp_path / "run"
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trainer = SimCLRTrainer(
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backbone,
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loader,
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{"epochs": 4, "amp": False, "log_interval": 100, "save_interval": 2,
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"projection": {"hidden_channels": 16, "out_channels": 8}},
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torch.device("cpu"),
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work_dir,
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)
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# 手动走前两个 epoch，模拟"训练中途"
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trainer.train_one_epoch(0)
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trainer.train_one_epoch(1)
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path = trainer.save_backbone(1)
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assert path.exists()
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assert torch.load(path, map_location="cpu", weights_only=False)["epochs"] == 2
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trainer.fit() # 完整跑完后 epochs 应更新
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assert torch.load(path, map_location="cpu", weights_only=False)["epochs"] == 4
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def _make_trainer(tiny_image_dir, work_dir, epochs=4, **cfg_extra):
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from torch.utils.data import DataLoader
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from datasets.unlabeled import UnlabeledImageDataset, unlabeled_collate
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dataset = UnlabeledImageDataset(
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tiny_image_dir,
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transforms=[{"name": "Resize", "size": [32, 32]}, {"name": "ToTensor"}],
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views=2,
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)
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loader = DataLoader(dataset, batch_size=4, shuffle=False, drop_last=True, collate_fn=unlabeled_collate)
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torch.manual_seed(0)
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backbone = BACKBONES.build({"name": "tiny_conv", "widths": [8, 16], "depths": [1, 1]})
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cfg = {
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"epochs": epochs,
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"amp": False,
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"log_interval": 100,
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"save_interval": 1,
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"projection": {"hidden_channels": 16, "out_channels": 8},
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"scheduler": {"name": "cosine"},
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"swanlab": {"enabled": False},
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**cfg_extra,
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}
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return SimCLRTrainer(backbone, loader, cfg, torch.device("cpu"), work_dir,
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resume=cfg_extra.pop("resume", None))
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def test_save_state_contains_full_training_state(tiny_image_dir, tmp_path):
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trainer = _make_trainer(tiny_image_dir, tmp_path / "run", epochs=1)
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trainer.fit()
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state_path = tmp_path / "run" / "simclr_last.pth"
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assert state_path.exists()
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state = torch.load(state_path, map_location="cpu", weights_only=False)
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# 续训需要的东西一个都不能少，否则动量和学习率进度会被清零
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assert {"backbone", "projector", "optimizer", "scheduler", "scaler", "epoch", "global_step"} <= set(state)
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assert state["epoch"] == 0
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def test_resume_continues_from_the_saved_epoch(tiny_image_dir, tmp_path):
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"""resume 是接着练，不是从头再来。"""
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work_dir = tmp_path / "run"
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first = _make_trainer(tiny_image_dir, work_dir, epochs=2)
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first.fit()
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steps_after_2 = first.global_step
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lr_after_2 = first.optimizer.param_groups[0]["lr"]
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resumed = SimCLRTrainer(
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BACKBONES.build({"name": "tiny_conv", "widths": [8, 16], "depths": [1, 1]}),
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first.dataloader,
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{"epochs": 5, "amp": False, "log_interval": 100, "save_interval": 1,
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"projection": {"hidden_channels": 16, "out_channels": 8},
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"scheduler": {"name": "cosine"}, "swanlab": {"enabled": False}},
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torch.device("cpu"),
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work_dir,
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resume=work_dir / "simclr_last.pth",
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)
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assert resumed.start_epoch == 2 # 从第 3 轮开始
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assert resumed.global_step == steps_after_2 # step 计数接上
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assert resumed.optimizer.param_groups[0]["lr"] == pytest.approx(lr_after_2) # 学习率进度接上
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resumed.fit()
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state = torch.load(work_dir / "simclr_last.pth", map_location="cpu", weights_only=False)
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assert state["epoch"] == 4 # 一路练到第 5 轮
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assert resumed.global_step > steps_after_2
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def test_resume_rejects_backbone_only_file(tiny_image_dir, tmp_path):
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"""simclr_backbone.pth 只有骨架，不能当续训状态用，要给出可操作的报错。"""
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work_dir = tmp_path / "run"
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_make_trainer(tiny_image_dir, work_dir, epochs=1).fit()
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with pytest.raises(ValueError, match="只含骨架权重"):
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SimCLRTrainer(
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BACKBONES.build({"name": "tiny_conv", "widths": [8, 16], "depths": [1, 1]}),
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_make_trainer(tiny_image_dir, work_dir, epochs=1).dataloader,
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{"epochs": 2, "amp": False, "projection": {"hidden_channels": 16, "out_channels": 8},
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"swanlab": {"enabled": False}},
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torch.device("cpu"),
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work_dir,
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resume=work_dir / "simclr_backbone.pth",
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)
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with pytest.raises(FileNotFoundError, match="不存在"):
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_make_trainer(tiny_image_dir, work_dir, epochs=1, resume=work_dir / "nope.pth")
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def test_resume_beyond_planned_epochs_does_not_train(tiny_image_dir, tmp_path):
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work_dir = tmp_path / "run"
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_make_trainer(tiny_image_dir, work_dir, epochs=3).fit()
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resumed = SimCLRTrainer(
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BACKBONES.build({"name": "tiny_conv", "widths": [8, 16], "depths": [1, 1]}),
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_make_trainer(tiny_image_dir, work_dir, epochs=1).dataloader,
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{"epochs": 3, "amp": False, "projection": {"hidden_channels": 16, "out_channels": 8},
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"swanlab": {"enabled": False}},
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torch.device("cpu"),
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work_dir,
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resume=work_dir / "simclr_last.pth",
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)
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steps_before = resumed.global_step
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resumed.fit()
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assert resumed.global_step == steps_before # 一步都没再训
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def test_resume_and_checkpoint_are_mutually_exclusive(tiny_image_dir, tmp_path, monkeypatch):
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sys.path.insert(0, "scripts")
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import cluster_unlabeled as cu
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with pytest.raises(ValueError, match="只能二选一"):
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cu.build_encoder(
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{"method": "simclr",
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"simclr": {"resume": "a.pth", "checkpoint": "b.pth"},
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"dataset": {"name": "unlabeled", "root": str(tiny_image_dir)}},
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torch.device("cpu"),
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tmp_path,
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)
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def test_cluster_script_simclr_branch_end_to_end(tiny_image_dir, tmp_path, monkeypatch):
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"""method=simclr 全流程：训练 -> 存权重 -> 抽特征 -> 聚类 -> 产出。"""
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sys.path.insert(0, "scripts")
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import cluster_unlabeled as cu
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work_dir = tmp_path / "run"
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monkeypatch.setattr(
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sys, "argv",
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["cluster_unlabeled.py", "--config", "configs/cluster/film.yaml",
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"--work-dir", str(work_dir), "--root", str(tiny_image_dir), "--set",
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"device=cpu", "method=simclr", "loader.num_workers=0", "loader.batch_size=4",
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"simclr.epochs=1", "simclr.batch_size=4", "simclr.amp=False",
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"simclr.backbone.widths=[8,16]", "simclr.backbone.depths=[1,1]",
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"simclr.projection.hidden_channels=16", "simclr.projection.out_channels=8",
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"num_clusters=2", "n_init=2"],
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)
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assert cu.main() == 0
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assert (work_dir / "simclr_backbone.pth").exists()
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assert (work_dir / "assignments.csv").exists()
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assert (work_dir / "summary.json").exists()
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assert (work_dir / "clusters" / "cluster_00").is_dir()
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def test_simclr_runs_on_the_resolved_device(tiny_image_dir, tmp_path, monkeypatch):
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"""method=simclr 在本机自动选中的后端上（MPS / CUDA / CPU）都应能跑通。"""
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sys.path.insert(0, "scripts")
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import cluster_unlabeled as cu
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from utils.device import describe_device, resolve_device
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device = resolve_device("auto")
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work_dir = tmp_path / "auto_run"
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monkeypatch.setattr(
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sys, "argv",
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["cluster_unlabeled.py", "--config", "configs/cluster/film.yaml",
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"--work-dir", str(work_dir), "--root", str(tiny_image_dir), "--set",
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"method=simclr", "loader.num_workers=0", "loader.batch_size=4",
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"simclr.epochs=1", "simclr.batch_size=4",
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"simclr.backbone.widths=[8,16]", "simclr.backbone.depths=[1,1]",
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"simclr.projection.hidden_channels=16", "simclr.projection.out_channels=8",
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"num_clusters=2", "n_init=2"],
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)
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assert cu.main() == 0, f"在 {describe_device(device)} 上跑失败"
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assert (work_dir / "simclr_backbone.pth").exists()
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