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import copy |
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import math |
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import torch |
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import torch.nn.functional as F |
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from torch import Tensor, nn |
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def _get_clones(module, N, layer_share=False): |
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if layer_share: |
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return nn.ModuleList([module for i in range(N)]) |
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else: |
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return nn.ModuleList([copy.deepcopy(module) for i in range(N)]) |
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def get_sine_pos_embed( |
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pos_tensor: torch.Tensor, |
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num_pos_feats: int = 128, |
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temperature: int = 10000, |
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exchange_xy: bool = True, |
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): |
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"""generate sine position embedding from a position tensor |
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Args: |
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pos_tensor (torch.Tensor): shape: [..., n]. |
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num_pos_feats (int): projected shape for each float in the tensor. |
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temperature (int): temperature in the sine/cosine function. |
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exchange_xy (bool, optional): exchange pos x and pos y. \ |
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For example, input tensor is [x,y], the results will be [pos(y), pos(x)]. Defaults to True. |
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Returns: |
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pos_embed (torch.Tensor): shape: [..., n*num_pos_feats]. |
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""" |
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scale = 2 * math.pi |
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dim_t = torch.arange(num_pos_feats, dtype=torch.float32, device=pos_tensor.device) |
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dim_t = temperature ** (2 * torch.div(dim_t, 2, rounding_mode="floor") / num_pos_feats) |
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def sine_func(x: torch.Tensor): |
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sin_x = x * scale / dim_t |
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sin_x = torch.stack((sin_x[..., 0::2].sin(), sin_x[..., 1::2].cos()), dim=3).flatten(2) |
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return sin_x |
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pos_res = [sine_func(x) for x in pos_tensor.split([1] * pos_tensor.shape[-1], dim=-1)] |
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if exchange_xy: |
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pos_res[0], pos_res[1] = pos_res[1], pos_res[0] |
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pos_res = torch.cat(pos_res, dim=-1) |
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return pos_res |
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def gen_encoder_output_proposals( |
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memory: Tensor, memory_padding_mask: Tensor, spatial_shapes: Tensor, learnedwh=None |
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): |
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""" |
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Input: |
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- memory: bs, \sum{hw}, d_model |
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- memory_padding_mask: bs, \sum{hw} |
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- spatial_shapes: nlevel, 2 |
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- learnedwh: 2 |
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Output: |
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- output_memory: bs, \sum{hw}, d_model |
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- output_proposals: bs, \sum{hw}, 4 |
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""" |
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N_, S_, C_ = memory.shape |
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proposals = [] |
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_cur = 0 |
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for lvl, (H_, W_) in enumerate(spatial_shapes): |
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mask_flatten_ = memory_padding_mask[:, _cur : (_cur + H_ * W_)].view(N_, H_, W_, 1) |
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valid_H = torch.sum(~mask_flatten_[:, :, 0, 0], 1) |
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valid_W = torch.sum(~mask_flatten_[:, 0, :, 0], 1) |
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grid_y, grid_x = torch.meshgrid( |
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torch.linspace(0, H_ - 1, H_, dtype=torch.float32, device=memory.device), |
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torch.linspace(0, W_ - 1, W_, dtype=torch.float32, device=memory.device), |
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) |
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grid = torch.cat([grid_x.unsqueeze(-1), grid_y.unsqueeze(-1)], -1) |
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scale = torch.cat([valid_W.unsqueeze(-1), valid_H.unsqueeze(-1)], 1).view(N_, 1, 1, 2) |
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grid = (grid.unsqueeze(0).expand(N_, -1, -1, -1) + 0.5) / scale |
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if learnedwh is not None: |
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wh = torch.ones_like(grid) * learnedwh.sigmoid() * (2.0**lvl) |
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else: |
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wh = torch.ones_like(grid) * 0.05 * (2.0**lvl) |
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proposal = torch.cat((grid, wh), -1).view(N_, -1, 4) |
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proposals.append(proposal) |
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_cur += H_ * W_ |
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output_proposals = torch.cat(proposals, 1) |
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output_proposals_valid = ((output_proposals > 0.01) & (output_proposals < 0.99)).all( |
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-1, keepdim=True |
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) |
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output_proposals = torch.log(output_proposals / (1 - output_proposals)) |
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output_proposals = output_proposals.masked_fill(memory_padding_mask.unsqueeze(-1), float("inf")) |
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output_proposals = output_proposals.masked_fill(~output_proposals_valid, float("inf")) |
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output_memory = memory |
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output_memory = output_memory.masked_fill(memory_padding_mask.unsqueeze(-1), float(0)) |
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output_memory = output_memory.masked_fill(~output_proposals_valid, float(0)) |
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return output_memory, output_proposals |
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class RandomBoxPerturber: |
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def __init__( |
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self, x_noise_scale=0.2, y_noise_scale=0.2, w_noise_scale=0.2, h_noise_scale=0.2 |
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) -> None: |
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self.noise_scale = torch.Tensor( |
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[x_noise_scale, y_noise_scale, w_noise_scale, h_noise_scale] |
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) |
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def __call__(self, refanchors: Tensor) -> Tensor: |
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nq, bs, query_dim = refanchors.shape |
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device = refanchors.device |
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noise_raw = torch.rand_like(refanchors) |
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noise_scale = self.noise_scale.to(device)[:query_dim] |
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new_refanchors = refanchors * (1 + (noise_raw - 0.5) * noise_scale) |
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return new_refanchors.clamp_(0, 1) |
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def sigmoid_focal_loss( |
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inputs, targets, num_boxes, alpha: float = 0.25, gamma: float = 2, no_reduction=False |
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): |
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""" |
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Loss used in RetinaNet for dense detection: https://arxiv.org/abs/1708.02002. |
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Args: |
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inputs: A float tensor of arbitrary shape. |
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The predictions for each example. |
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targets: A float tensor with the same shape as inputs. Stores the binary |
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classification label for each element in inputs |
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(0 for the negative class and 1 for the positive class). |
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alpha: (optional) Weighting factor in range (0,1) to balance |
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positive vs negative examples. Default = -1 (no weighting). |
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gamma: Exponent of the modulating factor (1 - p_t) to |
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balance easy vs hard examples. |
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Returns: |
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Loss tensor |
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""" |
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prob = inputs.sigmoid() |
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ce_loss = F.binary_cross_entropy_with_logits(inputs, targets, reduction="none") |
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p_t = prob * targets + (1 - prob) * (1 - targets) |
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loss = ce_loss * ((1 - p_t) ** gamma) |
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if alpha >= 0: |
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alpha_t = alpha * targets + (1 - alpha) * (1 - targets) |
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loss = alpha_t * loss |
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if no_reduction: |
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return loss |
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return loss.mean(1).sum() / num_boxes |
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class MLP(nn.Module): |
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"""Very simple multi-layer perceptron (also called FFN)""" |
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def __init__(self, input_dim, hidden_dim, output_dim, num_layers): |
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super().__init__() |
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self.num_layers = num_layers |
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h = [hidden_dim] * (num_layers - 1) |
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self.layers = nn.ModuleList( |
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nn.Linear(n, k) for n, k in zip([input_dim] + h, h + [output_dim]) |
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) |
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def forward(self, x): |
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for i, layer in enumerate(self.layers): |
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x = F.relu(layer(x)) if i < self.num_layers - 1 else layer(x) |
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return x |
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def _get_activation_fn(activation, d_model=256, batch_dim=0): |
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"""Return an activation function given a string""" |
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if activation == "relu": |
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return F.relu |
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if activation == "gelu": |
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return F.gelu |
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if activation == "glu": |
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return F.glu |
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if activation == "prelu": |
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return nn.PReLU() |
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if activation == "selu": |
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return F.selu |
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raise RuntimeError(f"activation should be relu/gelu, not {activation}.") |
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def gen_sineembed_for_position(pos_tensor): |
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scale = 2 * math.pi |
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dim_t = torch.arange(128, dtype=torch.float32, device=pos_tensor.device) |
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dim_t = 10000 ** (2 * (torch.div(dim_t, 2, rounding_mode='floor')) / 128) |
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x_embed = pos_tensor[:, :, 0] * scale |
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y_embed = pos_tensor[:, :, 1] * scale |
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pos_x = x_embed[:, :, None] / dim_t |
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pos_y = y_embed[:, :, None] / dim_t |
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pos_x = torch.stack((pos_x[:, :, 0::2].sin(), pos_x[:, :, 1::2].cos()), dim=3).flatten(2) |
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pos_y = torch.stack((pos_y[:, :, 0::2].sin(), pos_y[:, :, 1::2].cos()), dim=3).flatten(2) |
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if pos_tensor.size(-1) == 2: |
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pos = torch.cat((pos_y, pos_x), dim=2) |
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elif pos_tensor.size(-1) == 4: |
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w_embed = pos_tensor[:, :, 2] * scale |
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pos_w = w_embed[:, :, None] / dim_t |
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pos_w = torch.stack((pos_w[:, :, 0::2].sin(), pos_w[:, :, 1::2].cos()), dim=3).flatten(2) |
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h_embed = pos_tensor[:, :, 3] * scale |
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pos_h = h_embed[:, :, None] / dim_t |
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pos_h = torch.stack((pos_h[:, :, 0::2].sin(), pos_h[:, :, 1::2].cos()), dim=3).flatten(2) |
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pos = torch.cat((pos_y, pos_x, pos_w, pos_h), dim=2) |
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else: |
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raise ValueError("Unknown pos_tensor shape(-1):{}".format(pos_tensor.size(-1))) |
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return pos |
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class ContrastiveEmbed(nn.Module): |
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def __init__(self, max_text_len=256): |
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""" |
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Args: |
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max_text_len: max length of text. |
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""" |
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super().__init__() |
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self.max_text_len = max_text_len |
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def forward(self, x, text_dict): |
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"""_summary_ |
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Args: |
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x (_type_): _description_ |
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text_dict (_type_): _description_ |
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{ |
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'encoded_text': encoded_text, # bs, 195, d_model |
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'text_token_mask': text_token_mask, # bs, 195 |
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# True for used tokens. False for padding tokens |
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} |
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Returns: |
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_type_: _description_ |
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""" |
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assert isinstance(text_dict, dict) |
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y = text_dict["encoded_text"] |
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text_token_mask = text_dict["text_token_mask"] |
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res = x @ y.transpose(-1, -2) |
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res.masked_fill_(~text_token_mask[:, None, :], float("-inf")) |
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new_res = torch.full((*res.shape[:-1], self.max_text_len), float("-inf"), device=res.device) |
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new_res[..., : res.shape[-1]] = res |
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return new_res |
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