def _compute_mmd(self, phi_s, phi_t, y_hat, y_t_hat):
batch_size = int(phi_s.size()[0])
kernels = losses.gaussian_kernel(
phi_s,
phi_t,
kernel_mul=self._kernel_mul,
kernel_num=self._kernel_num,
)
return losses.compute_mmd_loss(kernels, batch_size)
def _compute_mmd(self, phi_s, phi_t, y_hat, y_t_hat):
softmax_layer = torch.nn.Softmax(dim=-1)
source_list = [phi_s, softmax_layer(y_hat)]
target_list = [phi_t, softmax_layer(y_t_hat)]
batch_size = int(phi_s.size()[0])
joint_kernels = None
for source, target, k_mul, k_num, sigma in zip(
source_list, target_list, self._kernel_mul, self._kernel_num, [None, 1.68]
):
kernels = losses.gaussian_kernel(source, target, kernel_mul=k_mul, kernel_num=k_num, fix_sigma=sigma)
if joint_kernels is not None:
joint_kernels = joint_kernels * kernels
else:
joint_kernels = kernels
return losses.compute_mmd_loss(joint_kernels, batch_size)
def compute_loss(self, batch, split_name="valid"):
x, y, domain_labels = batch
phi_x = self.forward(x)
tgt_idx = torch.where(domain_labels == self.target_label)[0]
n_src = len(self.src_domains)
domain_dist = 0
loss_cls = 0
ok_src = []
for src_domain in self.src_domains:
src_domain_idx = torch.where(
domain_labels == self.domain_to_idx[src_domain])[0]
phi_src = self.domain_net[src_domain].forward(
phi_x[src_domain_idx])
phi_tgt = self.domain_net[src_domain].forward(phi_x[tgt_idx])
kernels = losses.gaussian_kernel(
phi_src,
phi_tgt,
kernel_mul=self._kernel_mul,
kernel_num=self._kernel_num,
)
domain_dist += losses.compute_mmd_loss(kernels, len(phi_src))
y_src_hat = self.classifiers[src_domain](phi_src)
loss_cls_, ok_src_ = losses.cross_entropy_logits(
y_src_hat, y[src_domain_idx])
loss_cls += loss_cls_
ok_src.append(ok_src_)
domain_dist += self.cls_discrepancy(phi_x[tgt_idx])
loss_cls = loss_cls / n_src
ok_src = torch.cat(ok_src)
y_tgt_hat = self._get_avg_cls_output(phi_x[tgt_idx])
_, ok_tgt = losses.cross_entropy_logits(y_tgt_hat, y[tgt_idx])
task_loss = loss_cls
log_metrics = {
f"{split_name}_source_acc": ok_src,
f"{split_name}_target_acc": ok_tgt,
f"{split_name}_domain_acc": domain_dist,
}
return task_loss, domain_dist, log_metrics