def get_updates(self, loss, params):
# 是否更新
cond = K.equal(self.iterations % self.grad_accum_steps, 0)
cond = K.cast(cond, K.floatx())
# 获取梯度
grads = self.get_gradients(loss, params)
self.accum_grads = [
K.zeros(shape=K.int_shape(p),
dtype=K.dtype(p),
name='accum_grad_{}'.format(i))
for i, p in enumerate(params)
]
old_update = K.update
def new_update(x, new_x):
new_x = cond * new_x + (1 - cond) * x
return old_update(x, new_x)
K.update = new_update
updates = super(NewOptimizer, self).get_updates(loss, params)
K.update = old_update
# 累计更新
with K.control_dependencies(updates):
acc_updates = [
K.update(ag, g + (1 - cond) * ag)
for ag, g in zip(self.accum_grads, grads)
]
return acc_updates
def get_labels_of_similarity(self, y_pred):
idxs = K.arange(0, K.shape(y_pred)[0])
idxs_1 = idxs[None, :]
idxs_2 = (idxs + 1 - idxs % 2 * 2)[:, None]
labels = K.equal(idxs_1, idxs_2)
labels = K.cast(labels, K.floatx())
return labels
def sparse_accuracy(y_true, y_pred):
# y_true需要重新明确一下shape和dtype
y_true = K.reshape(y_true, K.shape(y_pred)[:-1])
y_true = K.cast(y_true, 'int32')
# 计算准确率
y_pred = K.cast(K.argmax(y_pred, axis=2), 'int32')
return K.mean(K.cast(K.equal(y_true, y_pred), K.floatx()))
def get_labels_of_similarity(self, inputs):
idx = K.arange(0, K.shape(inputs)[0])
idx_1 = idx[None, :]
idx_2 = (idx + 1 - idx % 2 * 2)[:, None]
labels = K.equal(idx_1, idx_2)
labels = K.cast(labels, K.floatx())
return labels
def get_label_mask(self, y_true):
"""获取batch内相同label样本"""
label = K.cast(y_true, 'int32')
label_2 = K.reshape(label, (1, -1))
mask = K.equal(label_2, label)
mask = K.cast(mask, K.floatx())
mask = mask * (1 - K.eye(K.shape(y_true)[0])) # 排除对角线，即 i == j
return mask
def sparse_accuracy(self, y_true, y_pred):
"""训练过程中显示逐帧准确率的函数，排除了mask的影响
此处y_true需要是整数形式（非one hot）
"""
# 导出mask并转换数据类型
mask = K.all(K.greater(y_pred, -1e6), axis=2)
mask = K.cast(mask, K.floatx())
# y_true需要重新明确一下shape和dtype
y_true = K.reshape(y_true, K.shape(y_pred)[:-1])
y_true = K.cast(y_true, 'int32')
# 逐标签取最大来粗略评测训练效果
y_pred = K.cast(K.argmax(y_pred, 2), 'int32')
isequal = K.cast(K.equal(y_true, y_pred), K.floatx())
return K.sum(isequal * mask) / K.sum(mask)
def _resource_apply(self, grad, var, indices=None):
"""interation % acc_steps==0 then update else accumulate
思路是先判断是否累计了 acc_steps，如果没有，则update时保持原样，
并累计当前梯度，否则，更新梯度并将累计的梯度置零
"""
# 是否更新
cond = K.equal(self.iterations % self.grad_accum_steps, 0)
# 获取梯度累计量
gradient_accumulation = self.get_slot(var, 'gradient_accumulation')
# 获取平均梯度
gradient_t = gradient_accumulation / self.grad_accum_steps
old_update = K.update
# 根据条件判断是否真的更新
def new_update(x, new_x):
new_x = K.switch(cond, new_x, x)
return old_update(x, new_x)
K.update = new_update
op = super(NewOptimizer, self)._resource_apply(gradient_t, var)
K.update = old_update
# 根据条件判断是否需要置零
with tf.control_dependencies([op]):
gradient_t = K.switch(cond,
K.zeros_like(gradient_accumulation),
gradient_accumulation)
with tf.control_dependencies(
[K.update(gradient_accumulation, gradient_t)]):
if indices is None:
K.update(gradient_accumulation,
gradient_accumulation + grad)
else:
self._resource_scatter_add(gradient_accumulation,
indices, grad)
return gradient_t
def compute_classification_acc(self, inputs, mask=None):
_, _, y_pred, _, y_true = inputs
equal = K.equal(K.cast(K.argmax(y_pred, axis=-1), 'int32'),
K.cast(y_true, 'int32'))
return K.cast(equal, K.floatx()) / K.cast(
K.shape(y_true)[0], K.floatx())