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# Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# This is modified from SpeechBrain
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# https://github.com/speechbrain/speechbrain/blob/085be635c07f16d42cd1295045bc46c407f1e15b/speechbrain/nnet/losses.py
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import math
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import paddle
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import paddle.nn as nn
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import paddle.nn.functional as F
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class AngularMargin(nn.Layer):
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def __init__(self, margin=0.0, scale=1.0):
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"""An implementation of Angular Margin (AM) proposed in the following
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paper: '''Margin Matters: Towards More Discriminative Deep Neural Network
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Embeddings for Speaker Recognition''' (https://arxiv.org/abs/1906.07317)
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Args:
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margin (float, optional): The margin for cosine similiarity. Defaults to 0.0.
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scale (float, optional): The scale for cosine similiarity. Defaults to 1.0.
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"""
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super(AngularMargin, self).__init__()
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self.margin = margin
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self.scale = scale
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def forward(self, outputs, targets):
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outputs = outputs - self.margin * targets
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return self.scale * outputs
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class AdditiveAngularMargin(AngularMargin):
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def __init__(self, margin=0.0, scale=1.0, easy_margin=False):
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"""The Implementation of Additive Angular Margin (AAM) proposed
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in the following paper: '''Margin Matters: Towards More Discriminative Deep Neural Network Embeddings for Speaker Recognition'''
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(https://arxiv.org/abs/1906.07317)
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Args:
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margin (float, optional): margin factor. Defaults to 0.0.
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scale (float, optional): scale factor. Defaults to 1.0.
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easy_margin (bool, optional): easy_margin flag. Defaults to False.
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"""
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super(AdditiveAngularMargin, self).__init__(margin, scale)
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self.easy_margin = easy_margin
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self.cos_m = math.cos(self.margin)
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self.sin_m = math.sin(self.margin)
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self.th = math.cos(math.pi - self.margin)
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self.mm = math.sin(math.pi - self.margin) * self.margin
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def forward(self, outputs, targets):
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cosine = outputs.astype('float32')
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sine = paddle.sqrt(1.0 - paddle.pow(cosine, 2))
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phi = cosine * self.cos_m - sine * self.sin_m # cos(theta + m)
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if self.easy_margin:
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phi = paddle.where(cosine > 0, phi, cosine)
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else:
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phi = paddle.where(cosine > self.th, phi, cosine - self.mm)
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outputs = (targets * phi) + ((1.0 - targets) * cosine)
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return self.scale * outputs
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class LogSoftmaxWrapper(nn.Layer):
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def __init__(self, loss_fn):
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"""Speaker identificatin loss function wrapper
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including all of compositions of the loss transformation
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Args:
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loss_fn (_type_): the loss value of a batch
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"""
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super(LogSoftmaxWrapper, self).__init__()
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self.loss_fn = loss_fn
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self.criterion = paddle.nn.KLDivLoss(reduction="sum")
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def forward(self, outputs, targets, length=None):
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targets = F.one_hot(targets, outputs.shape[1])
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try:
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predictions = self.loss_fn(outputs, targets)
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except TypeError:
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predictions = self.loss_fn(outputs)
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predictions = F.log_softmax(predictions, axis=1)
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loss = self.criterion(predictions, targets) / targets.sum()
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return loss
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class NCELoss(nn.Layer):
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"""Noise Contrastive Estimation loss funtion
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Noise Contrastive Estimation (NCE) is an approximation method that is used to
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work around the huge computational cost of large softmax layer.
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The basic idea is to convert the prediction problem into classification problem
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at training stage. It has been proved that these two criterions converges to
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the same minimal point as long as noise distribution is close enough to real one.
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NCE bridges the gap between generative models and discriminative models,
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rather than simply speedup the softmax layer.
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With NCE, you can turn almost anything into posterior with less effort (I think).
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Refs:
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NCE：http://www.cs.helsinki.fi/u/ahyvarin/papers/Gutmann10AISTATS.pdf
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Thanks: https://github.com/mingen-pan/easy-to-use-NCE-RNN-for-Pytorch/blob/master/nce.py
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Examples:
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Q = Q_from_tokens(output_dim)
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NCELoss(Q)
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"""
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def __init__(self, Q, noise_ratio=100, Z_offset=9.5):
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"""Noise Contrastive Estimation loss funtion
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Args:
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Q (tensor): prior model, uniform or guassian
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noise_ratio (int, optional): noise sampling times. Defaults to 100.
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Z_offset (float, optional): scale of post processing the score. Defaults to 9.5.
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"""
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super(NCELoss, self).__init__()
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assert type(noise_ratio) is int
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self.Q = paddle.to_tensor(Q, stop_gradient=False)
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self.N = self.Q.shape[0]
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self.K = noise_ratio
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self.Z_offset = Z_offset
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def forward(self, output, target):
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"""Forward inference
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Args:
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output (tensor): the model output, which is the input of loss function
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"""
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output = paddle.reshape(output, [-1, self.N])
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B = output.shape[0]
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noise_idx = self.get_noise(B)
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idx = self.get_combined_idx(target, noise_idx)
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P_target, P_noise = self.get_prob(idx, output, sep_target=True)
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Q_target, Q_noise = self.get_Q(idx)
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loss = self.nce_loss(P_target, P_noise, Q_noise, Q_target)
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return loss.mean()
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def get_Q(self, idx, sep_target=True):
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"""Get prior model of batchsize data
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"""
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idx_size = idx.size
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prob_model = paddle.to_tensor(
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self.Q.numpy()[paddle.reshape(idx, [-1]).numpy()])
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prob_model = paddle.reshape(prob_model, [idx.shape[0], idx.shape[1]])
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if sep_target:
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return prob_model[:, 0], prob_model[:, 1:]
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else:
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return prob_model
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def get_prob(self, idx, scores, sep_target=True):
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"""Post processing the score of post model(output of nn) of batchsize data
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"""
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scores = self.get_scores(idx, scores)
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scale = paddle.to_tensor([self.Z_offset], dtype='float64')
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scores = paddle.add(scores, -scale)
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prob = paddle.exp(scores)
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if sep_target:
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return prob[:, 0], prob[:, 1:]
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else:
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return prob
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def get_scores(self, idx, scores):
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"""Get the score of post model(output of nn) of batchsize data
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"""
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B, N = scores.shape
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K = idx.shape[1]
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idx_increment = paddle.to_tensor(
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N * paddle.reshape(paddle.arange(B), [B, 1]) * paddle.ones([1, K]),
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dtype="int64",
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stop_gradient=False)
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new_idx = idx_increment + idx
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new_scores = paddle.index_select(
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paddle.reshape(scores, [-1]), paddle.reshape(new_idx, [-1]))
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return paddle.reshape(new_scores, [B, K])
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def get_noise(self, batch_size, uniform=True):
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"""Select noise sample
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"""
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if uniform:
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noise = np.random.randint(self.N, size=self.K * batch_size)
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else:
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noise = np.random.choice(
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self.N, self.K * batch_size, replace=True, p=self.Q.data)
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noise = paddle.to_tensor(noise, dtype='int64', stop_gradient=False)
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noise_idx = paddle.reshape(noise, [batch_size, self.K])
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return noise_idx
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def get_combined_idx(self, target_idx, noise_idx):
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"""Combined target and noise
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"""
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target_idx = paddle.reshape(target_idx, [-1, 1])
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return paddle.concat((target_idx, noise_idx), 1)
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def nce_loss(self, prob_model, prob_noise_in_model, prob_noise,
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prob_target_in_noise):
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"""Combined the loss of target and noise
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"""
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def safe_log(tensor):
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"""Safe log
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"""
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EPSILON = 1e-10
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return paddle.log(EPSILON + tensor)
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model_loss = safe_log(prob_model /
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(prob_model + self.K * prob_target_in_noise))
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model_loss = paddle.reshape(model_loss, [-1])
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noise_loss = paddle.sum(
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safe_log((self.K * prob_noise) /
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(prob_noise_in_model + self.K * prob_noise)), -1)
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noise_loss = paddle.reshape(noise_loss, [-1])
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loss = -(model_loss + noise_loss)
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return loss
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class FocalLoss(nn.Layer):
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"""This criterion is a implemenation of Focal Loss, which is proposed in
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Focal Loss for Dense Object Detection.
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Loss(x, class) = - \alpha (1-softmax(x)[class])^gamma \log(softmax(x)[class])
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The losses are averaged across observations for each minibatch.
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Args:
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alpha(1D Tensor, Variable) : the scalar factor for this criterion
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gamma(float, double) : gamma > 0; reduces the relative loss for well-classified examples (p > .5),
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putting more focus on hard, misclassified examples
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size_average(bool): By default, the losses are averaged over observations for each minibatch.
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However, if the field size_average is set to False, the losses are
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instead summed for each minibatch.
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"""
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def __init__(self, alpha=1, gamma=0, size_average=True, ignore_index=-100):
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super(FocalLoss, self).__init__()
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self.alpha = alpha
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self.gamma = gamma
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self.size_average = size_average
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self.ce = nn.CrossEntropyLoss(
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ignore_index=ignore_index, reduction="none")
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def forward(self, outputs, targets):
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"""Forword inference.
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Args:
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outputs: input tensor
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target: target label tensor
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"""
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ce_loss = self.ce(outputs, targets)
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pt = paddle.exp(-ce_loss)
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focal_loss = self.alpha * (1 - pt)**self.gamma * ce_loss
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if self.size_average:
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return focal_loss.mean()
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else:
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return focal_loss.sum()
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if __name__ == "__main__":
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import numpy as np
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from paddlespeech.vector.utils.vector_utils import Q_from_tokens
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paddle.set_device("cpu")
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input_data = paddle.uniform([5, 100], dtype="float64")
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label_data = np.random.randint(0, 100, size=(5)).astype(np.int64)
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input = paddle.to_tensor(input_data)
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label = paddle.to_tensor(label_data)
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loss1 = FocalLoss()
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loss = loss1.forward(input, label)
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print("loss: %.5f" % (loss))
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Q = Q_from_tokens(100)
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loss2 = NCELoss(Q)
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loss = loss2.forward(input, label)
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print("loss: %.5f" % (loss))
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