Code refactoring

1. Separate FCs and triplet losses for HPM and PartNet
2. Remove FC-equivalent 1x1 conv layers in HPM
3. Support adjustable learning rate schedulers

10 files changed, 127 insertions, 161 deletions

diff --git a/config.py b/config.py
index d6de788..8abeba3 100644
--- a/config.py
+++ b/config.py
@@ -50,19 +50,17 @@ config: Configuration = {
             'ae_feature_channels': 64,
             # Appearance, canonical and pose feature dimensions
             'f_a_c_p_dims': (192, 192, 96),
-            # Use 1x1 convolution in dimensionality reduction
-            'hpm_use_1x1conv': False,
             # HPM pyramid scales, of which sum is number of parts
             'hpm_scales': (1, 2, 4, 8),
             # Global pooling method
             'hpm_use_avg_pool': True,
             'hpm_use_max_pool': True,
-            # Attention squeeze ratio
-            'tfa_squeeze_ratio': 4,
             # Number of parts after Part Net
             'tfa_num_parts': 16,
-            # Embedding dimension for each part
-            'embedding_dims': 256,
+            # Attention squeeze ratio
+            'tfa_squeeze_ratio': 4,
+            # Embedding dimensions for each part
+            'embedding_dims': (256, 256),
             # Batch Hard or Batch All
             'triplet_is_hard': True,
             # Use non-zero mean or sum
@@ -91,9 +89,14 @@ config: Configuration = {
         },
         'scheduler': {
             # Step start to decay
-            'start_step': 15_000,
+            'start_step': 500,
             # Multiplicative factor of decay in the end
-            'final_gamma': 0.001,
+            'final_gamma': 0.01,
+
+            # Local parameters (override global ones)
+            'hpm': {
+                'final_gamma': 0.001
+            }
         }
     },
     # Model metadata
@@ -107,6 +110,6 @@ config: Configuration = {
         # Restoration iteration (multiple models, e.g. nm, bg and cl)
         'restore_iters': (0, 0, 0),
         # Total iteration for training (multiple models)
-        'total_iters': (25_000, 25_000, 25_000),
+        'total_iters': (30_000, 40_000, 60_000),
     },
 }
diff --git a/models/auto_encoder.py b/models/auto_encoder.py
index e6a3e60..4fece69 100644
--- a/models/auto_encoder.py
+++ b/models/auto_encoder.py
@@ -171,7 +171,7 @@ class AutoEncoder(nn.Module):
 
             return (
                 (f_a_c1_t2_, f_c_c1_t2_, f_p_c1_t2_),
-                torch.stack((xrecon_loss, cano_cons_loss, pose_sim_loss * 10))
+                (xrecon_loss, cano_cons_loss, pose_sim_loss * 10)
             )
         else:  # evaluating
             return f_c_c1_t2_, f_p_c1_t2_
diff --git a/models/hpm.py b/models/hpm.py
index 9879cfb..8186b20 100644
--- a/models/hpm.py
+++ b/models/hpm.py
@@ -9,32 +9,26 @@ class HorizontalPyramidMatching(nn.Module):
             self,
             in_channels: int,
             out_channels: int = 128,
-            use_1x1conv: bool = False,
             scales: tuple[int, ...] = (1, 2, 4),
             use_avg_pool: bool = True,
             use_max_pool: bool = False,
-            **kwargs
     ):
         super().__init__()
-        self.in_channels = in_channels
-        self.out_channels = out_channels
-        self.use_1x1conv = use_1x1conv
         self.scales = scales
+        self.num_parts = sum(scales)
         self.use_avg_pool = use_avg_pool
         self.use_max_pool = use_max_pool
 
         self.pyramids = nn.ModuleList([
-            self._make_pyramid(scale, **kwargs) for scale in self.scales
+            self._make_pyramid(scale) for scale in scales
         ])
+        self.fc_mat = nn.Parameter(
+            torch.empty(self.num_parts, in_channels, out_channels)
+        )
 
-    def _make_pyramid(self, scale: int, **kwargs):
+    def _make_pyramid(self, scale: int):
         pyramid = nn.ModuleList([
-            HorizontalPyramidPooling(self.in_channels,
-                                     self.out_channels,
-                                     use_1x1conv=self.use_1x1conv,
-                                     use_avg_pool=self.use_avg_pool,
-                                     use_max_pool=self.use_max_pool,
-                                     **kwargs)
+            HorizontalPyramidPooling(self.use_avg_pool, self.use_max_pool)
             for _ in range(scale)
         ])
         return pyramid
@@ -52,4 +46,9 @@ class HorizontalPyramidMatching(nn.Module):
                 x_slice = x_slice.view(n, -1)
                 feature.append(x_slice)
         x = torch.stack(feature)
+
+        # p, n, c
+        x = x @ self.fc_mat
+        # p, n, d
+
         return x
diff --git a/models/layers.py b/models/layers.py
index f1d72b6..c609698 100644
--- a/models/layers.py
+++ b/models/layers.py
@@ -167,17 +167,10 @@ class BasicConv1d(nn.Module):
 class HorizontalPyramidPooling(nn.Module):
     def __init__(
             self,
-            in_channels: int,
-            out_channels: int,
-            use_1x1conv: bool = False,
             use_avg_pool: bool = True,
             use_max_pool: bool = False,
-            **kwargs
     ):
         super().__init__()
-        self.use_1x1conv = use_1x1conv
-        if use_1x1conv:
-            self.conv = BasicConv2d(in_channels, out_channels, 1, **kwargs)
         self.use_avg_pool = use_avg_pool
         self.use_max_pool = use_max_pool
         assert use_avg_pool or use_max_pool, 'Pooling layer(s) required.'
@@ -191,6 +184,4 @@ class HorizontalPyramidPooling(nn.Module):
             x = self.avg_pool(x)
         elif not self.use_avg_pool and self.use_max_pool:
             x = self.max_pool(x)
-        if self.use_1x1conv:
-            x = self.conv(x)
         return x
diff --git a/models/model.py b/models/model.py
index cb455f3..adea626 100644
--- a/models/model.py
+++ b/models/model.py
@@ -13,13 +13,15 @@ from torch.utils.data.dataloader import default_collate
 from torch.utils.tensorboard import SummaryWriter
 from tqdm import tqdm
 
+from models.hpm import HorizontalPyramidMatching
+from models.part_net import PartNet
 from models.rgb_part_net import RGBPartNet
 from utils.configuration import DataloaderConfiguration, \
     HyperparameterConfiguration, DatasetConfiguration, ModelConfiguration, \
     SystemConfiguration
 from utils.dataset import CASIAB, ClipConditions, ClipViews, ClipClasses
 from utils.sampler import TripletSampler
-from utils.triplet_loss import JointBatchTripletLoss, BatchTripletLoss
+from utils.triplet_loss import BatchTripletLoss
 
 
 class Model:
@@ -69,7 +71,8 @@ class Model:
         self._dataset_sig: str = 'undefined'
 
         self.rgb_pn: Optional[RGBPartNet] = None
-        self.triplet_loss: Optional[JointBatchTripletLoss] = None
+        self.triplet_loss_hpm: Optional[BatchTripletLoss] = None
+        self.triplet_loss_pn: Optional[BatchTripletLoss] = None
         self.optimizer: Optional[optim.Adam] = None
         self.scheduler: Optional[optim.lr_scheduler.StepLR] = None
         self.writer: Optional[SummaryWriter] = None
@@ -149,26 +152,28 @@ class Model:
         triplet_margins = model_hp.pop('triplet_margins', None)
         optim_hp: dict = self.hp.get('optimizer', {}).copy()
         ae_optim_hp = optim_hp.pop('auto_encoder', {})
-        pn_optim_hp = optim_hp.pop('part_net', {})
         hpm_optim_hp = optim_hp.pop('hpm', {})
-        fc_optim_hp = optim_hp.pop('fc', {})
+        pn_optim_hp = optim_hp.pop('part_net', {})
         sched_hp = self.hp.get('scheduler', {})
+        ae_sched_hp = sched_hp.get('auto_encoder', {})
+        hpm_sched_hp = sched_hp.get('hpm', {})
+        pn_sched_hp = sched_hp.get('part_net', {})
+
         self.rgb_pn = RGBPartNet(self.in_channels, self.in_size, **model_hp,
                                  image_log_on=self.image_log_on)
         # Hard margins
         if triplet_margins:
-            # Same margins
-            if triplet_margins[0] == triplet_margins[1]:
-                self.triplet_loss = BatchTripletLoss(
-                    triplet_is_hard, triplet_margins[0]
-                )
-            else:  # Different margins
-                self.triplet_loss = JointBatchTripletLoss(
-                    self.rgb_pn.hpm_num_parts,
-                    triplet_is_hard, triplet_is_mean, triplet_margins
-                )
+            self.triplet_loss_hpm = BatchTripletLoss(
+                triplet_is_hard, triplet_is_mean, triplet_margins[0]
+            )
+            self.triplet_loss_pn = BatchTripletLoss(
+                triplet_is_hard, triplet_is_mean, triplet_margins[1]
+            )
         else:  # Soft margins
-            self.triplet_loss = BatchTripletLoss(
+            self.triplet_loss_hpm = BatchTripletLoss(
+                triplet_is_hard, triplet_is_mean, None
+            )
+            self.triplet_loss_pn = BatchTripletLoss(
                 triplet_is_hard, triplet_is_mean, None
             )
 
@@ -177,25 +182,33 @@ class Model:
 
         # Try to accelerate computation using CUDA or others
         self.rgb_pn = self.rgb_pn.to(self.device)
-        self.triplet_loss = self.triplet_loss.to(self.device)
+        self.triplet_loss_hpm = self.triplet_loss_hpm.to(self.device)
+        self.triplet_loss_pn = self.triplet_loss_pn.to(self.device)
+
         self.optimizer = optim.Adam([
             {'params': self.rgb_pn.ae.parameters(), **ae_optim_hp},
-            {'params': self.rgb_pn.pn.parameters(), **pn_optim_hp},
             {'params': self.rgb_pn.hpm.parameters(), **hpm_optim_hp},
-            {'params': self.rgb_pn.fc_mat, **fc_optim_hp}
+            {'params': self.rgb_pn.pn.parameters(), **pn_optim_hp},
         ], **optim_hp)
-        sched_final_gamma = sched_hp.get('final_gamma', 0.001)
-        sched_start_step = sched_hp.get('start_step', 15_000)
-        all_step = self.total_iter - sched_start_step
-
-        def lr_lambda(epoch):
-            if epoch > sched_start_step:
-                passed_step = epoch - sched_start_step
-                return sched_final_gamma ** (passed_step / all_step)
-            else:
-                return 1
+
+        start_step = sched_hp.get('start_step', 15_000)
+        final_gamma = sched_hp.get('final_gamma', 0.001)
+        ae_start_step = ae_sched_hp.get('start_step', start_step)
+        ae_final_gamma = ae_sched_hp.get('final_gamma', final_gamma)
+        ae_all_step = self.total_iter - ae_start_step
+        hpm_start_step = hpm_sched_hp.get('start_step', start_step)
+        hpm_final_gamma = hpm_sched_hp.get('final_gamma', final_gamma)
+        hpm_all_step = self.total_iter - hpm_start_step
+        pn_start_step = pn_sched_hp.get('start_step', start_step)
+        pn_final_gamma = pn_sched_hp.get('final_gamma', final_gamma)
+        pn_all_step = self.total_iter - pn_start_step
         self.scheduler = optim.lr_scheduler.LambdaLR(self.optimizer, lr_lambda=[
-            lr_lambda, lr_lambda, lr_lambda, lr_lambda
+            lambda t: ae_final_gamma ** ((t - ae_start_step) / ae_all_step)
+            if t > ae_start_step else 1,
+            lambda t: hpm_final_gamma ** ((t - hpm_start_step) / hpm_all_step)
+            if t > hpm_start_step else 1,
+            lambda t: pn_final_gamma ** ((t - pn_start_step) / pn_all_step)
+            if t > pn_start_step else 1,
         ])
 
         self.writer = SummaryWriter(self._log_name)
@@ -220,7 +233,7 @@ class Model:
         running_loss = torch.zeros(5, device=self.device)
         print(f"{'Time':^8} {'Iter':^5} {'Loss':^6}",
               f"{'Xrecon':^8} {'CanoCons':^8} {'PoseSim':^8}",
-              f"{'BATripH':^8} {'BATripP':^8} {'LR':^9}")
+              f"{'TripHPM':^8} {'TripPN':^8} {'LRs':^29}")
         for (batch_c1, batch_c2) in dataloader:
             self.curr_iter += 1
             # Zero the parameter gradients
@@ -228,17 +241,20 @@ class Model:
             # forward + backward + optimize
             x_c1 = batch_c1['clip'].to(self.device)
             x_c2 = batch_c2['clip'].to(self.device)
-            embedding, ae_losses, images = self.rgb_pn(x_c1, x_c2)
+            embedding_c, embedding_p, ae_losses, images = self.rgb_pn(x_c1, x_c2)
             y = batch_c1['label'].to(self.device)
             # Duplicate labels for each part
-            y = y.repeat(self.rgb_pn.num_total_parts, 1)
-            trip_loss, dist, num_non_zero = self.triplet_loss(embedding, y)
-            losses = torch.cat((
-                ae_losses,
-                torch.stack((
-                    trip_loss[:self.rgb_pn.hpm_num_parts].mean(),
-                    trip_loss[self.rgb_pn.hpm_num_parts:].mean()
-                ))
+            y = y.repeat(self.rgb_pn.num_parts, 1)
+            trip_loss_hpm, hpm_dist, hpm_num_non_zero = self.triplet_loss_hpm(
+                embedding_c, y[:self.rgb_pn.hpm.num_parts]
+            )
+            trip_loss_pn, pn_dist, pn_num_non_zero = self.triplet_loss_pn(
+                embedding_p, y[self.rgb_pn.hpm.num_parts:]
+            )
+            losses = torch.stack((
+                *ae_losses,
+                trip_loss_hpm.mean(),
+                trip_loss_pn.mean()
             ))
             loss = losses.sum()
             loss.backward()
@@ -257,30 +273,30 @@ class Model:
                 'PartNet': losses[4]
             }, self.curr_iter)
             # None-zero losses in batch
-            if num_non_zero is not None:
+            if hpm_num_non_zero is not None and hpm_num_non_zero is not None:
                 self.writer.add_scalars('Loss/non-zero counts', {
-                    'HPM': num_non_zero[:self.rgb_pn.hpm_num_parts].mean(),
-                    'PartNet': num_non_zero[self.rgb_pn.hpm_num_parts:].mean()
+                    'HPM': hpm_num_non_zero.mean(),
+                    'PartNet': pn_num_non_zero.mean()
                 }, self.curr_iter)
             # Embedding distance
-            mean_hpm_dist = dist[:self.rgb_pn.hpm_num_parts].mean(0)
+            mean_hpm_dist = hpm_dist.mean(0)
             self._add_ranked_scalars(
                 'Embedding/HPM distance', mean_hpm_dist,
                 num_pos_pairs, num_pairs, self.curr_iter
             )
-            mean_pa_dist = dist[self.rgb_pn.hpm_num_parts:].mean(0)
+            mean_pa_dist = pn_dist.mean(0)
             self._add_ranked_scalars(
                 'Embedding/ParNet distance', mean_pa_dist,
                 num_pos_pairs, num_pairs, self.curr_iter
             )
             # Embedding norm
-            mean_hpm_embedding = embedding[:self.rgb_pn.hpm_num_parts].mean(0)
+            mean_hpm_embedding = embedding_c.mean(0)
             mean_hpm_norm = mean_hpm_embedding.norm(dim=-1)
             self._add_ranked_scalars(
                 'Embedding/HPM norm', mean_hpm_norm,
                 self.k, self.pr * self.k, self.curr_iter
             )
-            mean_pa_embedding = embedding[self.rgb_pn.hpm_num_parts:].mean(0)
+            mean_pa_embedding = embedding_p.mean(0)
             mean_pa_norm = mean_pa_embedding.norm(dim=-1)
             self._add_ranked_scalars(
                 'Embedding/PartNet norm', mean_pa_norm,
@@ -288,10 +304,9 @@ class Model:
             )
             # Learning rate
             lrs = self.scheduler.get_last_lr()
-            # Write learning rates
-            self.writer.add_scalar(
-                'Learning rate', lrs[0], self.curr_iter
-            )
+            self.writer.add_scalars('Learning rate', dict(zip((
+                'Auto-encoder', 'HPM', 'PartNet'
+            ), lrs)), self.curr_iter)
 
             if self.curr_iter % 100 == 0:
                 # Write disentangled images
@@ -316,7 +331,7 @@ class Model:
                 print(f'{hour:02}:{minute:02}:{second:02}',
                       f'{self.curr_iter:5d} {running_loss.sum() / 100:6.3f}',
                       '{:f} {:f} {:f} {:f} {:f}'.format(*running_loss / 100),
-                      f'{lrs[0]:.3e}')
+                      '{:.3e} {:.3e} {:.3e}'.format(*lrs))
                 running_loss.zero_()
 
             # Step scheduler
@@ -548,7 +563,7 @@ class Model:
             nn.init.zeros_(m.bias)
         elif isinstance(m, nn.Linear):
             nn.init.xavier_uniform_(m.weight)
-        elif isinstance(m, RGBPartNet):
+        elif isinstance(m, (HorizontalPyramidMatching, PartNet)):
             nn.init.xavier_uniform_(m.fc_mat)
 
     def _parse_dataset_config(
diff --git a/models/part_net.py b/models/part_net.py
index 29cf9cd..f2236bf 100644
--- a/models/part_net.py
+++ b/models/part_net.py
@@ -111,17 +111,21 @@ class PartNet(nn.Module):
     def __init__(
             self,
             in_channels: int = 128,
+            embedding_dims: int = 256,
+            num_parts: int = 16,
             squeeze_ratio: int = 4,
-            num_part: int = 16
     ):
         super().__init__()
-        self.num_part = num_part
-        self.tfa = TemporalFeatureAggregator(
-            in_channels, squeeze_ratio, self.num_part
-        )
+        self.num_part = num_parts
 
         self.avg_pool = nn.AdaptiveAvgPool2d(1)
         self.max_pool = nn.AdaptiveMaxPool2d(1)
+        self.tfa = TemporalFeatureAggregator(
+            in_channels, squeeze_ratio, self.num_part
+        )
+        self.fc_mat = nn.Parameter(
+            torch.empty(num_parts, in_channels, embedding_dims)
+        )
 
     def forward(self, x):
         n, t, c, h, w = x.size()
@@ -138,4 +142,8 @@ class PartNet(nn.Module):
 
         # p, n, t, c
         x = self.tfa(x)
+
+        # p, n, c
+        x = x @ self.fc_mat
+        # p, n, d
         return x
diff --git a/models/rgb_part_net.py b/models/rgb_part_net.py
index 8a0f3a7..c38a567 100644
--- a/models/rgb_part_net.py
+++ b/models/rgb_part_net.py
@@ -13,39 +13,31 @@ class RGBPartNet(nn.Module):
             ae_in_size: tuple[int, int] = (64, 48),
             ae_feature_channels: int = 64,
             f_a_c_p_dims: tuple[int, int, int] = (128, 128, 64),
-            hpm_use_1x1conv: bool = False,
             hpm_scales: tuple[int, ...] = (1, 2, 4),
             hpm_use_avg_pool: bool = True,
             hpm_use_max_pool: bool = True,
             tfa_squeeze_ratio: int = 4,
             tfa_num_parts: int = 16,
-            embedding_dims: int = 256,
+            embedding_dims: tuple[int] = (256, 256),
             image_log_on: bool = False
     ):
         super().__init__()
         self.h, self.w = ae_in_size
         (self.f_a_dim, self.f_c_dim, self.f_p_dim) = f_a_c_p_dims
-        self.hpm_num_parts = sum(hpm_scales)
         self.image_log_on = image_log_on
 
         self.ae = AutoEncoder(
             ae_in_channels, ae_in_size, ae_feature_channels, f_a_c_p_dims
         )
         self.pn_in_channels = ae_feature_channels * 2
-        self.pn = PartNet(
-            self.pn_in_channels, tfa_squeeze_ratio, tfa_num_parts
-        )
         self.hpm = HorizontalPyramidMatching(
-            ae_feature_channels * 2, self.pn_in_channels, hpm_use_1x1conv,
-            hpm_scales, hpm_use_avg_pool, hpm_use_max_pool
+            self.pn_in_channels, embedding_dims[0], hpm_scales,
+            hpm_use_avg_pool, hpm_use_max_pool
         )
-        self.num_total_parts = self.hpm_num_parts + tfa_num_parts
-        empty_fc = torch.empty(self.num_total_parts,
-                               self.pn_in_channels, embedding_dims)
-        self.fc_mat = nn.Parameter(empty_fc)
+        self.pn = PartNet(self.pn_in_channels, embedding_dims[1],
+                          tfa_num_parts, tfa_squeeze_ratio)
 
-    def fc(self, x):
-        return x @ self.fc_mat
+        self.num_parts = self.hpm.num_parts + tfa_num_parts
 
     def forward(self, x_c1, x_c2=None):
         # Step 1: Disentanglement
@@ -55,21 +47,17 @@ class RGBPartNet(nn.Module):
         # Step 2.a: Static Gait Feature Aggregation & HPM
         # n, c, h, w
         x_c = self.hpm(x_c)
-        # p, n, c
+        # p, n, d
 
         # Step 2.b: FPFE & TFA (Dynamic Gait Feature Aggregation)
         # n, t, c, h, w
         x_p = self.pn(x_p)
-        # p, n, c
-
-        # Step 3: Cat feature map together and fc
-        x = torch.cat((x_c, x_p))
-        x = self.fc(x)
+        # p, n, d
 
         if self.training:
-            return x, ae_losses, images
+            return x_c, x_p, ae_losses, images
         else:
-            return x.unsqueeze(1).view(-1)
+            return torch.cat((x_c, x_p)).unsqueeze(1).view(-1)
 
     def _disentangle(self, x_c1_t2, x_c2_t2=None):
         n, t, c, h, w = x_c1_t2.size()
diff --git a/test/part_net.py b/test/part_net.py
index 25e92ae..fada2c4 100644
--- a/test/part_net.py
+++ b/test/part_net.py
@@ -64,7 +64,7 @@ def test_custom_part_net():
                  paddings=((2, 1), (1, 1), (1, 1), (1, 1)),
                  halving=(1, 1, 3, 3),
                  squeeze_ratio=8,
-                 num_part=8)
+                 num_parts=8)
     x = torch.rand(T, N, 1, H, W)
     x = pa(x)
 
diff --git a/utils/configuration.py b/utils/configuration.py
index 0f8d9ff..f6ac182 100644
--- a/utils/configuration.py
+++ b/utils/configuration.py
@@ -33,16 +33,11 @@ class ModelHPConfiguration(TypedDict):
     ae_feature_channels: int
     f_a_c_p_dims: tuple[int, int, int]
     hpm_scales: tuple[int, ...]
-    hpm_use_1x1conv: bool
     hpm_use_avg_pool: bool
     hpm_use_max_pool: bool
-    fpfe_feature_channels: int
-    fpfe_kernel_sizes: tuple[tuple, ...]
-    fpfe_paddings: tuple[tuple, ...]
-    fpfe_halving: tuple[int, ...]
-    tfa_squeeze_ratio: int
     tfa_num_parts: int
-    embedding_dims: int
+    tfa_squeeze_ratio: int
+    embedding_dims: tuple[int]
     triplet_is_hard: bool
     triplet_is_mean: bool
     triplet_margins: tuple[float, float]
@@ -63,14 +58,21 @@ class OptimizerHPConfiguration(TypedDict):
     weight_decay: float
     amsgrad: bool
     auto_encoder: SubOptimizerHPConfiguration
-    part_net: SubOptimizerHPConfiguration
     hpm: SubOptimizerHPConfiguration
-    fc: SubOptimizerHPConfiguration
+    part_net: SubOptimizerHPConfiguration
+
+
+class SubSchedulerHPConfiguration(TypedDict):
+    start_step: int
+    final_gamma: float
 
 
 class SchedulerHPConfiguration(TypedDict):
     start_step: int
     final_gamma: float
+    auto_encoder: SubSchedulerHPConfiguration
+    hpm: SubSchedulerHPConfiguration
+    part_net: SubSchedulerHPConfiguration
 
 
 class HyperparameterConfiguration(TypedDict):
diff --git a/utils/triplet_loss.py b/utils/triplet_loss.py
index e05b69d..03fff21 100644
--- a/utils/triplet_loss.py
+++ b/utils/triplet_loss.py
@@ -85,43 +85,3 @@ class BatchTripletLoss(nn.Module):
         non_zero_mean = losses.sum(1) / non_zero_counts
         non_zero_mean[non_zero_counts == 0] = 0
         return non_zero_mean
-
-
-class JointBatchTripletLoss(BatchTripletLoss):
-    def __init__(
-            self,
-            hpm_num_parts: int,
-            is_hard: bool = True,
-            is_mean: bool = True,
-            margins: tuple[float, float] = (0.2, 0.2)
-    ):
-        super().__init__(is_hard, is_mean)
-        self.hpm_num_parts = hpm_num_parts
-        self.margin_hpm, self.margin_pn = margins
-
-    def forward(self, x, y):
-        p, n, c = x.size()
-        dist = self._batch_distance(x)
-        flat_dist_mask = torch.tril_indices(n, n, offset=-1, device=dist.device)
-        flat_dist = dist[:, flat_dist_mask[0], flat_dist_mask[1]]
-
-        if self.is_hard:
-            positive_negative_dist = self._hard_distance(dist, y, p, n)
-        else:  # is_all
-            positive_negative_dist = self._all_distance(dist, y, p, n)
-
-        hpm_part_loss = F.relu(
-            self.margin_hpm + positive_negative_dist[:self.hpm_num_parts]
-        )
-        pn_part_loss = F.relu(
-            self.margin_pn + positive_negative_dist[self.hpm_num_parts:]
-        )
-        losses = torch.cat((hpm_part_loss, pn_part_loss)).view(p, -1)
-
-        non_zero_counts = (losses != 0).sum(1).float()
-        if self.is_mean:
-            loss_metric = self._none_zero_mean(losses, non_zero_counts)
-        else:  # is_sum
-            loss_metric = losses.sum(1)
-
-        return loss_metric, flat_dist, non_zero_counts