python常用代码

常用代码片段及技巧

自动选择GPU和CPU

device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')
# model and tensor to device
vgg = models.vgg16().to(device)

切换当前目录

import os
try:
    os.chdir(os.path.join(os.getcwd(), '..'))
    print(os.getcwd())
except:
    pass

临时添加环境目录

import sys
sys.path.append('引用模块的地址')
print(sys.path)

打印模型参数

from torchsummary import summary
# 1 means in_channels
summary(model, (1, 28, 28))

将tensor的列表转换为tensor

x = torch.stack(tensor_list)

内存不够

• Smaller batch size
• torch.cuda.empty_cache()every few minibatches
• 分布式计算
• 训练数据和测试数据分开
• 每次用完之后删去variable，采用del x

debug tensor memory

resource` module is a Unix specific package as seen in https://docs.python.org/2/library/resource.html which is why it worked for you in Ubuntu, but raised an error when trying to use it in Windows.

Here is what solved it for me.

1. Downgrade to the Apache Spark 2.3.2 prebuild version
2. Install (or downgrade) jdk to version 1.8.0
   • My installed jdk was 1.9.0, which doesn't seem to be compatiable with spark 2.3.2 or 2.4.0
3. make sure that when you run java -version in cmd (command prompt), it show java version 8. If you are seeing version 9, you will need to change your system ENV PATH to ensure it points to java version 8.
4. Check this link to get help on changing the PATH if you have multiple java version installed.

device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')

def debug_memory():
    import collections, gc, resource, torch
    print('maxrss = {}'.format(
        resource.getrusage(resource.RUSAGE_SELF).ru_maxrss))
    tensors = collections.Counter((str(o.device), o.dtype, tuple(o.shape))
                                  for o in gc.get_objects()
                                  if torch.is_tensor(o))
    for line in sorted(tensors.items()):
        print('{}\t{}'.format(*line))
        
        
 # example
import tensor
 x = torch.tensor(3,3)
 debug_memory()
 
 y = torch.tensor(3,3)
 debug_memory()
 
 z = [torch.randn(i).long() for i in range(10)]
 debug_memory()