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A flexible and extensible metric learning library, written in PyTorch.

Project description


See this Google Spreadsheet for benchmark results (in progress).

See powerful_benchmarker to use the benchmarking tool.

Loss functions implemented:

  • angular
  • contrastive
  • lifted structure
  • margin
  • multi similarity
  • n pairs
  • nca
  • proxy nca
  • triplet margin
  • more to be added

Mining functions implemented:

  • distance weighted sampling
  • hard aware cascaded mining
  • maximum loss miner
  • multi similarity miner
  • pair margin miner
  • more to be added

Training methods implemented:

  • metric loss only
  • training with classifier
  • cascaded embeddings
  • deep adversarial metric learning
  • more to be added


pip install pytorch_metric_learning


Use a loss function by itself

from pytorch_metric_learning import losses
loss_func = losses.TripletMarginLoss(normalize_embeddings=False, margin=0.1)
loss = loss_func(embeddings, labels)

Or combine miners and loss functions, regardless of whether they mine or compute loss using pairs or triplets. Pairs are converted to triplets when necessary, and vice versa.

from pytorch_metric_learning import miners, losses
miner = miners.MultiSimilarityMiner(epsilon=0.1)
loss_func = losses.TripletMarginLoss(normalize_embeddings=False, margin=0.1)
hard_pairs = miner(embeddings, labels)
loss = loss_func(embeddings, labels, hard_pairs)

Train using more advanced approaches, like deep adversarial metric learning. For example:

from pytorch_metric_learning import trainers

# Set up your models, optimizers, loss functions etc.
models = {"trunk": your_trunk_model, 
          "embedder": your_embedder_model,
          "generator": your_negative_generator}

optimizers = {"trunk_optimizer": your_trunk_optimizer, 
              "embedder_optimizer": your_embedder_optimizer,
              "generator_optimizer": your_negative_generator_optimizer}

loss_funcs = {"metric_loss": losses.AngularNPairs(alpha=35),
              "synth_loss": losses.Angular(alpha=35), 
              "g_adv_loss": losses.Angular(alpha=35)}

mining_funcs = {}

loss_weights = {"metric_loss": 1, 
                "classifier_loss": 0,
                "synth_loss": 0.1,
                "g_adv_loss": 0.1,
                "g_hard_loss": 0.1,
                "g_reg_loss": 0.1}

# Create trainer object
trainer = trainers.DeepAdversarialMetricLearning(


Project details

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