atleast_2d in PyTorch

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*Memos:

• My post explains atleast_1d().
• My post explains atleast_3d().

atleast_2d() can get the view of the one or more 2D or more D tensors of zero or more elements by only changing one or more 0D or 1D tensors to one or more 2D tensors from the one or more 0D or more D tensors of zero or more elements as shown below:

*Memos:

• atleast_2d() can be used with torch but not with a tensor.
• The 1st or more arguments with torch are *tensors(Required-Type:tensor of int, float, complex or bool or tuple or list of tensor of int, float, complex or bool): *Memos:
  • If setting more than one tensors, a tuple of tensors is returned otherwise a tensor is returned.
  • Don’t use any keyword like *tensors=, tensor or input.
• Setting no arguments returns an empty tuple.

<span>import</span> <span>torch</span>
<span>tensor0</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>(</span><span>2</span><span>)</span> <span># 0D tensor </span>
<span>torch</span><span>.</span><span>atleast_2d</span><span>(</span><span>tensor0</span><span>)</span>
<span># tensor([[2]]) </span>
<span>tensor0</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>(</span><span>2</span><span>)</span> <span># 0D tensor </span><span>tensor1</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([</span><span>2</span><span>,</span> <span>7</span><span>,</span> <span>4</span><span>])</span> <span># 1D tensor </span><span>tensor2</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([[</span><span>2</span><span>,</span> <span>7</span><span>,</span> <span>4</span><span>],</span> <span>[</span><span>8</span><span>,</span> <span>3</span><span>,</span> <span>2</span><span>]])</span> <span># 2D tensor </span><span>tensor3</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([[[</span><span>2</span><span>,</span> <span>7</span><span>,</span> <span>4</span><span>],</span> <span>[</span><span>8</span><span>,</span> <span>3</span><span>,</span> <span>2</span><span>]],</span> <span># 3D tensor </span>                        <span>[[</span><span>5</span><span>,</span> <span>0</span><span>,</span> <span>8</span><span>],</span> <span>[</span><span>3</span><span>,</span> <span>6</span><span>,</span> <span>1</span><span>]]])</span>
<span>tensor4</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([[[[</span><span>2</span><span>,</span> <span>7</span><span>,</span> <span>4</span><span>],</span> <span>[</span><span>8</span><span>,</span> <span>3</span><span>,</span> <span>2</span><span>]],</span> <span># 4D tensor </span>                         <span>[[</span><span>5</span><span>,</span> <span>0</span><span>,</span> <span>8</span><span>],</span> <span>[</span><span>3</span><span>,</span> <span>6</span><span>,</span> <span>1</span><span>]]],</span>
                        <span>[[[</span><span>9</span><span>,</span> <span>4</span><span>,</span> <span>7</span><span>],</span> <span>[</span><span>1</span><span>,</span> <span>0</span><span>,</span> <span>5</span><span>]],</span>
                         <span>[[</span><span>6</span><span>,</span> <span>7</span><span>,</span> <span>4</span><span>],</span> <span>[</span><span>2</span><span>,</span> <span>1</span><span>,</span> <span>9</span><span>]]]])</span>
<span>torch</span><span>.</span><span>atleast_2d</span><span>(</span><span>tensor0</span><span>,</span> <span>tensor1</span><span>,</span> <span>tensor2</span><span>,</span> <span>tensor3</span><span>,</span> <span>tensor4</span><span>)</span>
<span>torch</span><span>.</span><span>atleast_2d</span><span>((</span><span>tensor0</span><span>,</span> <span>tensor1</span><span>,</span> <span>tensor2</span><span>,</span> <span>tensor3</span><span>,</span> <span>tensor4</span><span>))</span>
<span># (tensor([[2]]), # tensor([[2, 7, 4]]), # tensor([[2, 7, 4], [8, 3, 2]]), # tensor([[[2, 7, 4], [8, 3, 2]], # [[5, 0, 8], [3, 6, 1]]]), # tensor([[[[2, 7, 4], [8, 3, 2]], # [[5, 0, 8], [3, 6, 1]]], # [[[9, 4, 7], [1, 0, 5]], # [[6, 7, 4], [2, 1, 9]]]])) </span>
<span>tensor0</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>(</span><span>2</span><span>)</span> <span># 0D tensor </span><span>tensor1</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([</span><span>2</span><span>,</span> <span>7</span><span>,</span> <span>4</span><span>])</span> <span># 1D tensor </span><span>tensor2</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([[</span><span>2.</span><span>,</span> <span>7.</span><span>,</span> <span>4.</span><span>],</span> <span># 2D tensor </span>                        <span>[</span><span>8.</span><span>,</span> <span>3.</span><span>,</span> <span>2.</span><span>]])</span>
<span>tensor3</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([[[</span><span>2.</span><span>+</span><span>0.j</span><span>,</span> <span>7.</span><span>+</span><span>0.j</span><span>,</span> <span>4.</span><span>+</span><span>0.j</span><span>],</span> <span># 3D tensor </span>                         <span>[</span><span>8.</span><span>+</span><span>0.j</span><span>,</span> <span>3.</span><span>+</span><span>0.j</span><span>,</span> <span>2.</span><span>+</span><span>0.j</span><span>]],</span>
                        <span>[[</span><span>5.</span><span>+</span><span>0.j</span><span>,</span> <span>0.</span><span>+</span><span>0.j</span><span>,</span> <span>8.</span><span>+</span><span>0.j</span><span>],</span>
                         <span>[</span><span>3.</span><span>+</span><span>0.j</span><span>,</span> <span>6.</span><span>+</span><span>0.j</span><span>,</span> <span>1.</span><span>+</span><span>0.j</span><span>]]])</span>
<span>tensor4</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([[[[</span><span>True</span><span>,</span> <span>False</span><span>,</span> <span>True</span><span>],</span> <span>[</span><span>False</span><span>,</span> <span>True</span><span>,</span> <span>False</span><span>]],</span>
                         <span>[[</span><span>True</span><span>,</span> <span>False</span><span>,</span> <span>True</span><span>],</span> <span>[</span><span>False</span><span>,</span> <span>True</span><span>,</span> <span>False</span><span>]]],</span>
                        <span>[[[</span><span>True</span><span>,</span> <span>False</span><span>,</span> <span>True</span><span>],</span> <span>[</span><span>False</span><span>,</span> <span>True</span><span>,</span> <span>False</span><span>]],</span>
                         <span>[[</span><span>True</span><span>,</span> <span>False</span><span>,</span> <span>True</span><span>],</span> <span>[</span><span>False</span><span>,</span> <span>True</span><span>,</span> <span>False</span><span>]]]])</span>
                       <span># 4D tensor </span><span>torch</span><span>.</span><span>atleast_2d</span><span>(</span><span>tensor0</span><span>,</span> <span>tensor1</span><span>,</span> <span>tensor2</span><span>,</span> <span>tensor3</span><span>,</span> <span>tensor4</span><span>)</span>
<span># (tensor([[2]]), # tensor([[2, 7, 4]]), # tensor([[2., 7., 4.], # [8., 3., 2.]]), # tensor([[[2.+0.j, 7.+0.j, 4.+0.j], # [8.+0.j, 3.+0.j, 2.+0.j]], # [[5.+0.j, 0.+0.j, 8.+0.j], # [3.+0.j, 6.+0.j, 1.+0.j]]]), # tensor([[[[True, False, True], [False, True, False]], # [[True, False, True], [False, True, False]]], # [[[True, False, True], [False, True, False]], # [[True, False, True], [False, True, False]]]])) </span>
<span>torch</span><span>.</span><span>atleast_2d</span><span>()</span>
<span># () </span>
<span>import</span> <span>torch</span>

<span>tensor0</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>(</span><span>2</span><span>)</span> <span># 0D tensor </span>
<span>torch</span><span>.</span><span>atleast_2d</span><span>(</span><span>tensor0</span><span>)</span>
<span># tensor([[2]]) </span>
<span>tensor0</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>(</span><span>2</span><span>)</span> <span># 0D tensor </span><span>tensor1</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([</span><span>2</span><span>,</span> <span>7</span><span>,</span> <span>4</span><span>])</span> <span># 1D tensor </span><span>tensor2</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([[</span><span>2</span><span>,</span> <span>7</span><span>,</span> <span>4</span><span>],</span> <span>[</span><span>8</span><span>,</span> <span>3</span><span>,</span> <span>2</span><span>]])</span> <span># 2D tensor </span><span>tensor3</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([[[</span><span>2</span><span>,</span> <span>7</span><span>,</span> <span>4</span><span>],</span> <span>[</span><span>8</span><span>,</span> <span>3</span><span>,</span> <span>2</span><span>]],</span> <span># 3D tensor </span>                        <span>[[</span><span>5</span><span>,</span> <span>0</span><span>,</span> <span>8</span><span>],</span> <span>[</span><span>3</span><span>,</span> <span>6</span><span>,</span> <span>1</span><span>]]])</span>
<span>tensor4</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([[[[</span><span>2</span><span>,</span> <span>7</span><span>,</span> <span>4</span><span>],</span> <span>[</span><span>8</span><span>,</span> <span>3</span><span>,</span> <span>2</span><span>]],</span> <span># 4D tensor </span>                         <span>[[</span><span>5</span><span>,</span> <span>0</span><span>,</span> <span>8</span><span>],</span> <span>[</span><span>3</span><span>,</span> <span>6</span><span>,</span> <span>1</span><span>]]],</span>
                        <span>[[[</span><span>9</span><span>,</span> <span>4</span><span>,</span> <span>7</span><span>],</span> <span>[</span><span>1</span><span>,</span> <span>0</span><span>,</span> <span>5</span><span>]],</span>
                         <span>[[</span><span>6</span><span>,</span> <span>7</span><span>,</span> <span>4</span><span>],</span> <span>[</span><span>2</span><span>,</span> <span>1</span><span>,</span> <span>9</span><span>]]]])</span>
<span>torch</span><span>.</span><span>atleast_2d</span><span>(</span><span>tensor0</span><span>,</span> <span>tensor1</span><span>,</span> <span>tensor2</span><span>,</span> <span>tensor3</span><span>,</span> <span>tensor4</span><span>)</span>
<span>torch</span><span>.</span><span>atleast_2d</span><span>((</span><span>tensor0</span><span>,</span> <span>tensor1</span><span>,</span> <span>tensor2</span><span>,</span> <span>tensor3</span><span>,</span> <span>tensor4</span><span>))</span>
<span># (tensor([[2]]), # tensor([[2, 7, 4]]), # tensor([[2, 7, 4], [8, 3, 2]]), # tensor([[[2, 7, 4], [8, 3, 2]], # [[5, 0, 8], [3, 6, 1]]]), # tensor([[[[2, 7, 4], [8, 3, 2]], # [[5, 0, 8], [3, 6, 1]]], # [[[9, 4, 7], [1, 0, 5]], # [[6, 7, 4], [2, 1, 9]]]])) </span>
<span>tensor0</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>(</span><span>2</span><span>)</span> <span># 0D tensor </span><span>tensor1</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([</span><span>2</span><span>,</span> <span>7</span><span>,</span> <span>4</span><span>])</span> <span># 1D tensor </span><span>tensor2</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([[</span><span>2.</span><span>,</span> <span>7.</span><span>,</span> <span>4.</span><span>],</span> <span># 2D tensor </span>                        <span>[</span><span>8.</span><span>,</span> <span>3.</span><span>,</span> <span>2.</span><span>]])</span>
<span>tensor3</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([[[</span><span>2.</span><span>+</span><span>0.j</span><span>,</span> <span>7.</span><span>+</span><span>0.j</span><span>,</span> <span>4.</span><span>+</span><span>0.j</span><span>],</span> <span># 3D tensor </span>                         <span>[</span><span>8.</span><span>+</span><span>0.j</span><span>,</span> <span>3.</span><span>+</span><span>0.j</span><span>,</span> <span>2.</span><span>+</span><span>0.j</span><span>]],</span>
                        <span>[[</span><span>5.</span><span>+</span><span>0.j</span><span>,</span> <span>0.</span><span>+</span><span>0.j</span><span>,</span> <span>8.</span><span>+</span><span>0.j</span><span>],</span>
                         <span>[</span><span>3.</span><span>+</span><span>0.j</span><span>,</span> <span>6.</span><span>+</span><span>0.j</span><span>,</span> <span>1.</span><span>+</span><span>0.j</span><span>]]])</span>
<span>tensor4</span> <span>=</span> <span>torch</span><span>.</span><span>tensor</span><span>([[[[</span><span>True</span><span>,</span> <span>False</span><span>,</span> <span>True</span><span>],</span> <span>[</span><span>False</span><span>,</span> <span>True</span><span>,</span> <span>False</span><span>]],</span>
                         <span>[[</span><span>True</span><span>,</span> <span>False</span><span>,</span> <span>True</span><span>],</span> <span>[</span><span>False</span><span>,</span> <span>True</span><span>,</span> <span>False</span><span>]]],</span>
                        <span>[[[</span><span>True</span><span>,</span> <span>False</span><span>,</span> <span>True</span><span>],</span> <span>[</span><span>False</span><span>,</span> <span>True</span><span>,</span> <span>False</span><span>]],</span>
                         <span>[[</span><span>True</span><span>,</span> <span>False</span><span>,</span> <span>True</span><span>],</span> <span>[</span><span>False</span><span>,</span> <span>True</span><span>,</span> <span>False</span><span>]]]])</span>
                       <span># 4D tensor </span><span>torch</span><span>.</span><span>atleast_2d</span><span>(</span><span>tensor0</span><span>,</span> <span>tensor1</span><span>,</span> <span>tensor2</span><span>,</span> <span>tensor3</span><span>,</span> <span>tensor4</span><span>)</span>
<span># (tensor([[2]]), # tensor([[2, 7, 4]]), # tensor([[2., 7., 4.], # [8., 3., 2.]]), # tensor([[[2.+0.j, 7.+0.j, 4.+0.j], # [8.+0.j, 3.+0.j, 2.+0.j]], # [[5.+0.j, 0.+0.j, 8.+0.j], # [3.+0.j, 6.+0.j, 1.+0.j]]]), # tensor([[[[True, False, True], [False, True, False]], # [[True, False, True], [False, True, False]]], # [[[True, False, True], [False, True, False]], # [[True, False, True], [False, True, False]]]])) </span>
<span>torch</span><span>.</span><span>atleast_2d</span><span>()</span>
<span># () </span>
import torch

tensor0 = torch.tensor(2) # 0D tensor 
torch.atleast_2d(tensor0)
# tensor([[2]]) 
tensor0 = torch.tensor(2) # 0D tensor tensor1 = torch.tensor([2, 7, 4]) # 1D tensor tensor2 = torch.tensor([[2, 7, 4], [8, 3, 2]]) # 2D tensor tensor3 = torch.tensor([[[2, 7, 4], [8, 3, 2]], # 3D tensor                         [[5, 0, 8], [3, 6, 1]]])
tensor4 = torch.tensor([[[[2, 7, 4], [8, 3, 2]], # 4D tensor                          [[5, 0, 8], [3, 6, 1]]],
                        [[[9, 4, 7], [1, 0, 5]],
                         [[6, 7, 4], [2, 1, 9]]]])
torch.atleast_2d(tensor0, tensor1, tensor2, tensor3, tensor4)
torch.atleast_2d((tensor0, tensor1, tensor2, tensor3, tensor4))
# (tensor([[2]]), # tensor([[2, 7, 4]]), # tensor([[2, 7, 4], [8, 3, 2]]), # tensor([[[2, 7, 4], [8, 3, 2]], # [[5, 0, 8], [3, 6, 1]]]), # tensor([[[[2, 7, 4], [8, 3, 2]], # [[5, 0, 8], [3, 6, 1]]], # [[[9, 4, 7], [1, 0, 5]], # [[6, 7, 4], [2, 1, 9]]]])) 
tensor0 = torch.tensor(2) # 0D tensor tensor1 = torch.tensor([2, 7, 4]) # 1D tensor tensor2 = torch.tensor([[2., 7., 4.], # 2D tensor                         [8., 3., 2.]])
tensor3 = torch.tensor([[[2.+0.j, 7.+0.j, 4.+0.j], # 3D tensor                          [8.+0.j, 3.+0.j, 2.+0.j]],
                        [[5.+0.j, 0.+0.j, 8.+0.j],
                         [3.+0.j, 6.+0.j, 1.+0.j]]])
tensor4 = torch.tensor([[[[True, False, True], [False, True, False]],
                         [[True, False, True], [False, True, False]]],
                        [[[True, False, True], [False, True, False]],
                         [[True, False, True], [False, True, False]]]])
                       # 4D tensor torch.atleast_2d(tensor0, tensor1, tensor2, tensor3, tensor4)
# (tensor([[2]]), # tensor([[2, 7, 4]]), # tensor([[2., 7., 4.], # [8., 3., 2.]]), # tensor([[[2.+0.j, 7.+0.j, 4.+0.j], # [8.+0.j, 3.+0.j, 2.+0.j]], # [[5.+0.j, 0.+0.j, 8.+0.j], # [3.+0.j, 6.+0.j, 1.+0.j]]]), # tensor([[[[True, False, True], [False, True, False]], # [[True, False, True], [False, True, False]]], # [[[True, False, True], [False, True, False]], # [[True, False, True], [False, True, False]]]])) 
torch.atleast_2d()
# () 

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原文链接：atleast_2d in PyTorch