torch.mean()的使用方法

对一个三维数组的每一维度进行操作

1，dim=0

a = torch.Tensor([0, 1, 2, 3, 4, 5,6,7]).view(2, 2, 2) 
print(a) 
mean = torch.mean(a, 0) 
print(mean, mean.shape)

输出结果：

tensor([[[0., 1.],

             [2., 3.]],

             [[4., 5.],

              [6., 7.]]])

tensor([[2., 3.],

            [4., 5.]]) torch.Size([2, 2])

2，dim=1

a = torch.Tensor([0, 1, 2, 3, 4, 5,6,7]).view(2, 2, 2) 
print(a) 
mean = torch.mean(a, 1) 
print(mean, mean.shape)

输出结果

tensor(

[[[0., 1.],

[2., 3.]],

[[4., 5.],

[6., 7.]]])

tensor(

[[1., 2.],

[5., 6.]]) torch.Size([2, 2])

3，dim=2

a = torch.Tensor([0, 1, 2, 3, 4, 5,6,7]).view(2, 2, 2) 
print(a) 
mean = torch.mean(a, 2) 
print(mean, mean.shape)

输出结果

tensor(

[[[0., 1.],

[2., 3.]],

[[4., 5.],

[6., 7.]]])

tensor(

[[0.5000, 2.5000],

[4.5000, 6.5000]]) torch.Size([2, 2])

补充，如果在函数中添加了True,表示要和原来数的维度一致，不够的用维度1来添加，如下

a = torch.Tensor([0, 1, 2, 3, 4, 5,6,7]).view(2, 2, 2) 
print(a) 
mean = torch.mean(a, 2, True) 
print(mean, mean.shape)
tensor([[[0., 1.],[2., 3.]],[[4., 5.],[6., 7.]]])
tensor([[[0.5000],[2.5000]],[[4.5000],[6.5000]]]) torch.Size([2, 2, 1])

补充多维度变化

a = torch.Tensor([0, 1, 2, 3, 4, 5,6,7,8,9,10,11,12,13,14,15]).view(2, 2, 2,2) 
print(a) 
mean = torch.mean(a, 0, True) 
print(mean, mean.shape)
tensor([[[[ 0.,  1.],[ 2.,  3.]],[[ 4.,  5.],[ 6.,  7.]]],[[[ 8.,  9.],[10., 11.]],[[12., 13.],[14., 15.]]]])
tensor([[[[ 4.,  5.],[ 6.,  7.]],[[ 8.,  9.],[10., 11.]]]]) torch.Size([1, 2, 2, 2])

a = torch.Tensor([0, 1, 2, 3, 4, 5,6,7,8,9,10,11,12,13,14,15]).view(2, 2, 2,2) 
print(a) 
mean = torch.mean(a, 1, True) 
print(mean, mean.shape)
tensor([[[[ 0.,  1.],[ 2.,  3.]],[[ 4.,  5.],[ 6.,  7.]]],[[[ 8.,  9.],[10., 11.]],[[12., 13.],[14., 15.]]]])
tensor([[[[ 2.,  3.],[ 4.,  5.]]],[[[10., 11.],[12., 13.]]]]) torch.Size([2, 1, 2, 2])

a = torch.Tensor([0, 1, 2, 3, 4, 5,6,7,8,9,10,11,12,13,14,15]).view(2, 2, 2,2) 
print(a) 
mean = torch.mean(a, 2, True) 
print(mean, mean.shape)tensor([[[[ 0.,  1.],[ 2.,  3.]],[[ 4.,  5.],[ 6.,  7.]]],[[[ 8.,  9.],[10., 11.]],[[12., 13.],[14., 15.]]]])
tensor([[[[ 1.,  2.]],[[ 5.,  6.]]],[[[ 9., 10.]],[[13., 14.]]]]) torch.Size([2, 2, 1, 2])

a = torch.Tensor([0, 1, 2, 3, 4, 5,6,7,8,9,10,11,12,13,14,15]).view(2, 2, 2,2) 
print(a) 
mean = torch.mean(a, 3, True) 
print(mean, mean.shape)
tensor([[[[ 0.,  1.],[ 2.,  3.]],[[ 4.,  5.],[ 6.,  7.]]],[[[ 8.,  9.],[10., 11.]],[[12., 13.],[14., 15.]]]])
tensor([[[[ 0.5000],[ 2.5000]],[[ 4.5000],[ 6.5000]]],[[[ 8.5000],[10.5000]],[[12.5000],[14.5000]]]]) torch.Size([2, 2, 2, 1])

a = torch.Tensor([0, 1, 2, 3, 4, 5,6,7,8,9,10,11,12,13,14,15,0, 1, 2, 3, 4, 5,6,7,8,9,10,11,12,13,14,15]).view(2, 2, 2,2,2) 
print(a) 
mean = torch.mean(a, 3, True) 
print(mean, mean.shape)
tensor([[[[[ 0.,  1.],[ 2.,  3.]],[[ 4.,  5.],[ 6.,  7.]]],[[[ 8.,  9.],[10., 11.]],[[12., 13.],[14., 15.]]]],[[[[ 0.,  1.],[ 2.,  3.]],[[ 4.,  5.],[ 6.,  7.]]],[[[ 8.,  9.],[10., 11.]],[[12., 13.],[14., 15.]]]]])
tensor([[[[[ 1.,  2.]],[[ 5.,  6.]]],[[[ 9., 10.]],[[13., 14.]]]],[[[[ 1.,  2.]],[[ 5.,  6.]]],[[[ 9., 10.]],[[13., 14.]]]]]) torch.Size([2, 2, 2, 1, 2])