95 lines
2.8 KiB
Python
95 lines
2.8 KiB
Python
"""Dynamically prune 'loser' prototypes in GLVQ-type models."""
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import argparse
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import prototorch as pt
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import pytorch_lightning as pl
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import torch
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from pytorch_lightning.callbacks import Callback
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class PrototypePruning(Callback):
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def __init__(self, threshold=0.01, prune_after=10, verbose=False):
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self.threshold = threshold
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self.prune_after = prune_after
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self.verbose = verbose
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def on_epoch_start(self, trainer, pl_module):
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pl_module.initialize_prototype_win_ratios()
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def on_epoch_end(self, trainer, pl_module):
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if (trainer.current_epoch + 1) > self.prune_after:
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ratios = pl_module.prototype_win_ratios.mean(dim=0)
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to_prune = torch.arange(len(ratios))[ratios < self.threshold]
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if len(to_prune) > 0:
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if self.verbose:
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print(f"\nPrototype win ratios: {ratios}")
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print(f"Pruning prototypes at indices: {to_prune}")
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cur_num_protos = pl_module.num_prototypes
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pl_module.remove_prototypes(indices=to_prune)
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new_num_protos = pl_module.num_prototypes
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if self.verbose:
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print(f"`num_prototypes` reduced from {cur_num_protos} "
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f"to {new_num_protos}.")
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if __name__ == "__main__":
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# Command-line arguments
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parser = argparse.ArgumentParser()
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parser = pl.Trainer.add_argparse_args(parser)
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args = parser.parse_args()
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# Dataset
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num_classes = 4
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num_features = 2
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num_clusters = 1
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train_ds = pt.datasets.Random(num_samples=500,
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num_classes=num_classes,
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num_features=num_features,
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num_clusters=num_clusters,
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separation=3.0,
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seed=42)
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# Dataloaders
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train_loader = torch.utils.data.DataLoader(train_ds, batch_size=256)
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# Hyperparameters
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prototypes_per_class = num_clusters * 5
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hparams = dict(
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distribution=(num_classes, prototypes_per_class),
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lr=0.3,
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)
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# Initialize the model
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model = pt.models.CELVQ(
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hparams,
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prototype_initializer=pt.components.Ones(2, scale=3),
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)
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# Summary
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print(model)
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# Callbacks
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vis = pt.models.VisGLVQ2D(train_ds)
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pruning = PrototypePruning(
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threshold=0.01, # prune prototype if it wins less than 1%
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prune_after=50,
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verbose=True,
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)
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# Setup trainer
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trainer = pl.Trainer.from_argparse_args(
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args,
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max_epochs=100,
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callbacks=[
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vis,
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pruning,
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],
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terminate_on_nan=True,
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weights_summary=None,
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accelerator="ddp",
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)
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# Training loop
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trainer.fit(model, train_loader)
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