def forward()

in easycv/models/loss/iou_loss.py [0:0]


    def forward(self, pred, target):
        assert pred.shape[0] == target.shape[0]
        if target.dtype != pred.dtype:
            target = target.to(pred.dtype)
        pred = pred.view(-1, 4)
        target = target.view(-1, 4)
        tl = torch.max((pred[:, :2] - pred[:, 2:] / 2),
                       (target[:, :2] - target[:, 2:] / 2))
        br = torch.min((pred[:, :2] + pred[:, 2:] / 2),
                       (target[:, :2] + target[:, 2:] / 2))

        area_p = torch.prod(pred[:, 2:], 1)
        area_g = torch.prod(target[:, 2:], 1)

        en = (tl < br).type(tl.type()).prod(dim=1)
        area_i = torch.prod(br - tl, 1) * en
        iou = (area_i) / (area_p + area_g - area_i + 1e-16)

        if self.loss_type == 'iou':
            loss = 1 - iou**2

        elif self.loss_type == 'siou':
            # angle cost
            c_h = torch.max(pred[:, 1], target[:, 1]) - torch.min(
                pred[:, 1], target[:, 1])
            c_w = torch.max(pred[:, 0], target[:, 0]) - torch.min(
                pred[:, 0], target[:, 0])
            sigma = torch.sqrt(((pred[:, :2] - target[:, :2])**2).sum(dim=1))

            angle_cost = 2 * (c_h * c_w) / (sigma**2)

            # distance cost
            gamma = 2 - angle_cost
            # gamma = 1
            c_dw = torch.max(pred[:, 0], target[:, 0]) - torch.min(
                pred[:, 0], target[:, 0]) + (pred[:, 2] + target[:, 2]) / 2
            c_dh = torch.max(pred[:, 1], target[:, 1]) - torch.min(
                pred[:, 1], target[:, 1]) + (pred[:, 3] + target[:, 3]) / 2
            p_x = ((target[:, 0] - pred[:, 0]) / c_dw)**2
            p_y = ((target[:, 1] - pred[:, 1]) / c_dh)**2
            dist_cost = 2 - torch.exp(-gamma * p_x) - torch.exp(-gamma * p_y)

            # shape cost
            theta = 4
            w_w = torch.abs(pred[:, 2] - target[:, 2]) / torch.max(
                pred[:, 2], target[:, 2])
            w_h = torch.abs(pred[:, 3] - target[:, 3]) / torch.max(
                pred[:, 3], target[:, 3])
            shape_cost = torch.pow((1 - torch.exp(-w_w)), theta) + torch.pow(
                (1 - torch.exp(-w_h)), theta)

            loss = 1 - iou + (dist_cost + shape_cost) / 2

        elif self.loss_type == 'giou':
            c_tl = torch.min((pred[:, :2] - pred[:, 2:] / 2),
                             (target[:, :2] - target[:, 2:] / 2))
            c_br = torch.max((pred[:, :2] + pred[:, 2:] / 2),
                             (target[:, :2] + target[:, 2:] / 2))
            area_c = torch.prod(c_br - c_tl, 1)
            giou = iou - (area_c - area_i) / area_c.clamp(1e-16)
            loss = 1 - giou.clamp(min=-1.0, max=1.0)

        elif self.loss_type == 'diou':
            c_tl = torch.min((pred[:, :2] - pred[:, 2:] / 2),
                             (target[:, :2] - target[:, 2:] / 2))
            c_br = torch.max((pred[:, :2] + pred[:, 2:] / 2),
                             (target[:, :2] + target[:, 2:] / 2))
            convex_dis = torch.pow(c_br[:, 0] - c_tl[:, 0], 2) + torch.pow(
                c_br[:, 1] - c_tl[:, 1], 2) + 1e-7  # convex diagonal squared

            center_dis = (torch.pow(pred[:, 0] - target[:, 0], 2) +
                          torch.pow(pred[:, 1] - target[:, 1], 2)
                          )  # center diagonal squared

            diou = iou - (center_dis / convex_dis)
            loss = 1 - diou.clamp(min=-1.0, max=1.0)

        elif self.loss_type == 'ciou':
            c_tl = torch.min((pred[:, :2] - pred[:, 2:] / 2),
                             (target[:, :2] - target[:, 2:] / 2))
            c_br = torch.max((pred[:, :2] + pred[:, 2:] / 2),
                             (target[:, :2] + target[:, 2:] / 2))
            convex_dis = torch.pow(c_br[:, 0] - c_tl[:, 0], 2) + torch.pow(
                c_br[:, 1] - c_tl[:, 1], 2) + 1e-7  # convex diagonal squared

            center_dis = (torch.pow(pred[:, 0] - target[:, 0], 2) +
                          torch.pow(pred[:, 1] - target[:, 1], 2)
                          )  # center diagonal squared

            v = (4 / math.pi**2) * torch.pow(
                torch.atan(target[:, 2] / torch.clamp(target[:, 3], min=1e-7))
                - torch.atan(pred[:, 2] / torch.clamp(pred[:, 3], min=1e-7)),
                2)

            with torch.no_grad():
                alpha = v / ((1 + 1e-7) - iou + v)

            ciou = iou - (center_dis / convex_dis + alpha * v)

            loss = 1 - ciou.clamp(min=-1.0, max=1.0)

        elif self.loss_type == 'eiou':

            c_tl = torch.min((pred[:, :2] - pred[:, 2:] / 2),
                             (target[:, :2] - target[:, 2:] / 2))
            c_br = torch.max((pred[:, :2] + pred[:, 2:] / 2),
                             (target[:, :2] + target[:, 2:] / 2))
            convex_dis = torch.pow(c_br[:, 0] - c_tl[:, 0], 2) + torch.pow(
                c_br[:, 1] - c_tl[:, 1], 2) + 1e-7  # convex diagonal squared

            center_dis = (torch.pow(pred[:, 0] - target[:, 0], 2) +
                          torch.pow(pred[:, 1] - target[:, 1], 2)
                          )  # center diagonal squared

            dis_w = torch.pow(pred[:, 2] - target[:, 2], 2)
            dis_h = torch.pow(pred[:, 3] - target[:, 3], 2)

            C_w = torch.pow(c_br[:, 0] - c_tl[:, 0], 2) + 1e-7
            C_h = torch.pow(c_br[:, 1] - c_tl[:, 1], 2) + 1e-7

            eiou = iou - (center_dis / convex_dis) - (dis_w / C_w) - (
                dis_h / C_h)

            loss = 1 - eiou.clamp(min=-1.0, max=1.0)

        if self.reduction == 'mean':
            loss = loss.mean()
        elif self.reduction == 'sum':
            loss = loss.sum()

        return loss