基于余弦退火的warm up的pytorch代码实现
时间: 2023-06-26 08:06:00 浏览: 204
以下是基于余弦退火的warm up的PyTorch代码实现:
```python
import math
import torch
from torch.optim.lr_scheduler import LambdaLR
class CosineAnnealingWarmupLR(LambdaLR):
def __init__(self, optimizer, T_max, eta_min=0, warmup_steps=0, last_epoch=-1):
self.T_max = T_max
self.eta_min = eta_min
self.warmup_steps = warmup_steps
super(CosineAnnealingWarmupLR, self).__init__(optimizer, self.lr_lambda, last_epoch)
def lr_lambda(self, step):
if step < self.warmup_steps:
return float(step) / float(max(1, self.warmup_steps)) * self.eta_min
else:
return self.eta_min + (1 - self.eta_min) * (
1 + math.cos(math.pi * (step - self.warmup_steps) / (self.T_max - self.warmup_steps))) / 2
```
使用方式:
```python
# 定义优化器
optimizer = torch.optim.Adam(model.parameters(), lr=0.001)
# 定义学习率调度程序
scheduler = CosineAnnealingWarmupLR(optimizer, T_max=10, eta_min=0, warmup_steps=5)
# 训练循环中更新学习率
for epoch in range(num_epochs):
for batch_idx, (data, target) in enumerate(train_loader):
optimizer.zero_grad()
output = model(data)
loss = loss_func(output, target)
loss.backward()
optimizer.step()
scheduler.step()
```
上述代码中,`T_max`是余弦退火的最大周期,`eta_min`是学习率下限,`warmup_steps`是warm up的步数。在使用时,我们需要将这些参数根据具体情况进行调整。
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