👩‍💻torch.Tensor vs torch.tensor

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torch Tensor 객체 생성 방법 비교와 Inverted 연산 확인하기
Published

December 21, 2022

공통점과 차이점

공통점

둘다 data(input)에 대해서 Tensor 객체로 만들어 주는 기능은 동일

차이점

  • torch.tensor() : function

    • docs: https://pytorch.org/docs/stable/generated/torch.tensor.html#torch.tensor
    • torch.tensor(data)에서 data는 필수 argument. (data 없을 시 TypeError)
    • torch.tensor는 항상 data를 복사
    • int 입력 시 int 그대로 입력
    • 입력받은 데이터를 새로운 메모리 공간에 복사해 Tensor 객체 생성 (call by value)

  • torch.Tensor() : class

    • docs: https://pytorch.org/docs/stable/tensors.html#torch.Tensor
    • 이미 생성된 객체를 tensor로 바꾸고 싶을 때 사용
    • 빈 Tensor 객체를 만들 때 사용
    • int 입력 시 float로 변환
    • Tensor 객체로 데이터를 입력할 경우 입력 받은 메모리 공간 그대로 사용 (call by reference)
    • list나 numpy 등 다른 자료형으로 입력 받을 경우 값을 복사하여 Tensor 객체 생성(call by value)

torch.tensor()

import torch
original_data = torch.tensor([1])
new_data = torch.tensor(original_data)
print(f"original : {original_data} {original_data.dtype}")
print(f"new : {new_data} {new_data.dtype}")

 
# original data를 수정
original_data[0] = 2
print(f"original : {original_data} {original_data.dtype}")
print(f"new : {new_data} {new_data.dtype}")
original : tensor([1]) torch.int64
new : tensor([1]) torch.int64
original : tensor([2]) torch.int64
new : tensor([1]) torch.int64
/tmp/ipykernel_847781/1124094978.py:2: UserWarning: To copy construct from a tensor, it is recommended to use sourceTensor.clone().detach() or sourceTensor.clone().detach().requires_grad_(True), rather than torch.tensor(sourceTensor).
  new_data = torch.tensor(original_data)
  • int에서 int로
  • call by value, 새로운 Tensor 객체이므로 변화 x

torch.Tensor()

original_data = torch.Tensor([1])
new_data = torch.Tensor(original_data)
print(f"original : {original_data} {original_data.dtype}")
print(f"new : {new_data} {new_data.dtype}")

 
# original data를 수정
original_data[0] = 2
print(f"original : {original_data} {original_data.dtype}")
print(f"new : {new_data} {new_data.dtype}")
original : tensor([1.]) torch.float32
new : tensor([1.]) torch.float32
original : tensor([2.]) torch.float32
new : tensor([2.]) torch.float32
  • int에서 float으로
  • call by reference, shallow copy
original_data = [1]
new_data = torch.Tensor(original_data)
print(f"original : {original_data}")
print(f"new : {new_data} {new_data.dtype}")

# original data를 수정
original_data[0] = 2
print(f"original : {original_data}")
print(f"new : {new_data} {new_data.dtype}")
original : [1]
new : tensor([1.]) torch.float32
original : [2]
new : tensor([1.]) torch.float32
  • int에서 float으로
  • call by value, deep copy

Inverted ~ 연산 적용 차이

~ (operator.invert) is only implemented on integer and Boolean-type tensors

torch.tensor()

a = torch.tensor([0,1,10])
print(f"Shape of tensor: {a.shape}")
print(f"Datatype of tensor: {a.dtype}")
print(f"Device tensor is stored on: {a.device}")
Shape of tensor: torch.Size([3])
Datatype of tensor: torch.int64
Device tensor is stored on: cpu
~a
tensor([ -1,  -2, -11])
b = torch.tensor([True, False, True])
print(f"Shape of tensor: {b.shape}")
print(f"Datatype of tensor: {b.dtype}")
print(f"Device tensor is stored on: {b.device}")
Shape of tensor: torch.Size([3])
Datatype of tensor: torch.bool
Device tensor is stored on: cpu
~b
tensor([False,  True, False])
c = torch.tensor([0.13, 1.5, -.116])
print(f"Shape of tensor: {c.shape}")
print(f"Datatype of tensor: {c.dtype}")
print(f"Device tensor is stored on: {c.device}")
Shape of tensor: torch.Size([3])
Datatype of tensor: torch.float32
Device tensor is stored on: cpu
~c
TypeError: ~ (operator.invert) is only implemented on integer and Boolean-type tensors

torch.Tensor()

a = torch.Tensor([0,1,10])
print(f"Shape of tensor: {a.shape}")
print(f"Datatype of tensor: {a.dtype}")
print(f"Device tensor is stored on: {a.device}")
Shape of tensor: torch.Size([3])
Datatype of tensor: torch.float32
Device tensor is stored on: cpu
a
tensor([ 0.,  1., 10.])
~a
TypeError: ~ (operator.invert) is only implemented on integer and Boolean-type tensors
b = torch.Tensor([True, False, True])
print(f"Shape of tensor: {b.shape}")
print(f"Datatype of tensor: {b.dtype}")
print(f"Device tensor is stored on: {b.device}")
Shape of tensor: torch.Size([3])
Datatype of tensor: torch.float32
Device tensor is stored on: cpu
b
tensor([1., 0., 1.])
~b
TypeError: ~ (operator.invert) is only implemented on integer and Boolean-type tensors
c = torch.Tensor([0.13, 1.5, -.116])
print(f"Shape of tensor: {c.shape}")
print(f"Datatype of tensor: {c.dtype}")
print(f"Device tensor is stored on: {c.device}")
Shape of tensor: torch.Size([3])
Datatype of tensor: torch.float32
Device tensor is stored on: cpu
c
tensor([ 0.1300,  1.5000, -0.1160])
~c
TypeError: ~ (operator.invert) is only implemented on integer and Boolean-type tensors

결론: torch.tensor()로만 ~연산 사용 가능

Reference