人臉識(shí)別損失函數(shù)的匯總 | Pytorch版本實(shí)現(xiàn)

class Linear(nn.Module):    def __init__(self):        super(Linear, self).__init__()        self.weight = nn.Parameter(torch.Tensor(2, 10))  # (input,output)        nn.init.xavier_uniform_(self.weight)
    def forward(self, x, label):        out = x.mm(self.weight)        loss = F.cross_entropy(out, label)        return out, loss

class Modified(nn.Module):    def __init__(self):        super(Modified, self).__init__()        self.weight = nn.Parameter(torch.Tensor(2,10))#(input,output)        nn.init.xavier_uniform_(self.weight)        self.weight.data.uniform_(-1,1).renorm_(2,1,1e-5).mul_(1e5)        #因?yàn)閞enorm采用的是maxnorm，所以先縮小再放大以防止norm結(jié)果小于1
    def forward(self, x):        w=self.weight        ww=w.renorm(2,1,1e-5).mul(1e5)        out = x.mm(ww)        return out

class NormFace(nn.Module):    def __init__(self):        super(NormFace, self).__init__()        self.weight = nn.Parameter(torch.Tensor(2, 10))  # (input,output)        nn.init.xavier_uniform_(self.weight)        self.weight.data.uniform_(-1, 1).renorm_(2, 1, 1e-5).mul_(1e5)        self.s = 16        # 因?yàn)閞enorm采用的是maxnorm，所以先縮小再放大以防止norm結(jié)果小于1
    def forward(self, x, label):        cosine = F.normalize(x).mm(F.normalize(self.weight, dim=0))        loss = F.cross_entropy(self.s * cosine, label)        return cosine, loss

class SphereFace(nn.Module):    def __init__(self, m=4):        super(SphereFace, self).__init__()        self.weight = nn.Parameter(torch.Tensor(2, 10))  # (input,output)        nn.init.xavier_uniform_(self.weight)        self.weight.data.renorm_(2, 1, 1e-5).mul_(1e5)        self.m = m        self.mlambda = [  # calculate cos(mx)            lambda x: x ** 0,            lambda x: x ** 1,            lambda x: 2 * x ** 2 - 1,            lambda x: 4 * x ** 3 - 3 * x,            lambda x: 8 * x ** 4 - 8 * x ** 2 + 1,            lambda x: 16 * x ** 5 - 20 * x ** 3 + 5 * x        ]        self.it = 0        self.LambdaMin = 3        self.LambdaMax = 30000.0        self.gamma = 0
    def forward(self, input, label):        # 注意，在原始的A-softmax中是不對(duì)x進(jìn)行標(biāo)準(zhǔn)化的,        # 標(biāo)準(zhǔn)化可以提升性能，也會(huì)增加收斂難度，A-softmax本來就很難收斂
        cos_theta = F.normalize(input).mm(F.normalize(self.weight, dim=0))        cos_theta = cos_theta.clamp(-1, 1)  # 防止出現(xiàn)異常        # 以上計(jì)算出了傳統(tǒng)意義上的cos_theta，但為了cos(m*theta)的單調(diào)遞減，需要使用phi_theta
        cos_m_theta = self.mlambda[self.m](cos_theta)        # 計(jì)算theta，依據(jù)theta的區(qū)間把k的取值定下來        theta = cos_theta.data.acos()        k = (self.m * theta / 3.1415926).floor()        phi_theta = ((-1) ** k) * cos_m_theta - 2 * k
        x_norm = input.pow(2).sum(1).pow(0.5)  # 這個(gè)地方?jīng)Q定x帶不帶模長(zhǎng)，不帶就要乘s        x_cos_theta = cos_theta * x_norm.view(-1, 1)        x_phi_theta = phi_theta * x_norm.view(-1, 1)
        ############ 以上計(jì)算target logit，下面構(gòu)造loss，退火訓(xùn)練#####        self.it += 1  # 用來調(diào)整lambda        target = label.view(-1, 1)  # (B,1)
        onehot = torch.zeros(target.shape[0], 10).cuda().scatter_(1, target, 1)
        lamb = max(self.LambdaMin, self.LambdaMax / (1 + 0.2 * self.it))
        output = x_cos_theta * 1.0  # 如果不乘可能會(huì)有數(shù)值錯(cuò)誤？        output[onehot.byte()] -= x_cos_theta[onehot.byte()] * (1.0 + 0) / (1 + lamb)        output[onehot.byte()] += x_phi_theta[onehot.byte()] * (1.0 + 0) / (1 + lamb)        # 到這一步可以等同于原來的Wx+b=y的輸出了，
        # 到這里使用了Focal Loss，如果直接使用cross_Entropy的話似乎效果會(huì)減弱許多        log = F.log_softmax(output, 1)        log = log.gather(1, target)
        log = log.view(-1)        pt = log.data.exp()        loss = -1 * (1 - pt) ** self.gamma * log
        loss = loss.mean()        # loss = F.cross_entropy(x_cos_theta,target.view(-1))#換成crossEntropy效果會(huì)差        return output, loss

class ArcMarginProduct(nn.Module):    def __init__(self, s=32, m=0.5):        super(ArcMarginProduct, self).__init__()        self.in_feature = 2        self.out_feature = 10        self.s = s        self.m = m        self.weight = nn.Parameter(torch.Tensor(2, 10))  # (input,output)        nn.init.xavier_uniform_(self.weight)        self.weight.data.renorm_(2, 1, 1e-5).mul_(1e5)
        self.cos_m = math.cos(m)        self.sin_m = math.sin(m)        # 為了保證cos(theta+m)在0-pi單調(diào)遞減：        self.th = math.cos(3.1415926 - m)        self.mm = math.sin(3.1415926 - m) * m
    def forward(self, x, label):        cosine = F.normalize(x).mm(F.normalize(self.weight, dim=0))        cosine = cosine.clamp(-1, 1)  # 數(shù)值穩(wěn)定        sine = torch.sqrt(torch.max(1.0 - torch.pow(cosine, 2), torch.ones(cosine.shape).cuda() * 1e-7))  # 數(shù)值穩(wěn)定
        ##print(self.sin_m)        phi = cosine * self.cos_m - sine * self.sin_m  # 兩角和公式        # # 為了保證cos(theta+m)在0-pi單調(diào)遞減：        # phi = torch.where((cosine - self.th) > 0, phi, cosine - self.mm)#必要性未知        #        one_hot = torch.zeros_like(cosine)        one_hot.scatter_(1, label.view(-1, 1), 1)        output = (one_hot * phi) + ((1.0 - one_hot) * cosine)
        output = output * self.s        loss = F.cross_entropy(output, label)
        return output, loss

class centerloss(nn.Module):    def __init__(self):        super(centerloss, self).__init__()        self.center = nn.Parameter(10 * torch.randn(10, 2))        self.lamda = 0.2        self.weight = nn.Parameter(torch.Tensor(2, 10))  # (input,output)        nn.init.xavier_uniform_(self.weight)
    def forward(self, feature, label):        batch_size = label.size()[0]        nCenter = self.center.index_select(dim=0, index=label)        distance = feature.dist(nCenter)        centerloss = (1 / 2.0 / batch_size) * distance        out = feature.mm(self.weight)        ceLoss = F.cross_entropy(out, label)        return out, ceLoss + self.lamda * centerloss