where is torch.tensor.item() defined at the Github?

user_12906108 0
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I am torch Newbie.

when I was learning torch tutorial like below,
I was curious about where tensor.item() is defined.

import torch
a = torch.tensor([1])
print( a.item() )  # it works without problem.

In order to find what i dont know,

First, I used VScode. but I got this.
enter image description here
not like this
enter image description here

Second, I searched "def item()" at the torch Github
But, I could not find. T^T

Could you tell me where tensor.item() is defined at the Github?

Or

where Class_torch.tensor's Menber functions(Method function) are defined??

torch pytorch python
1 Answers

Short answer:

torch/csrc/autograd/python_variable_indexing.cpp:268

Long answer:

I hope you like C++. ;)

The first thing to know is that item() isn't (usually) a method in most Python classes. Instead, Python converts calls to item() into other underlying methods like __getitem__() as a convenience. Knowing that:

class Tensor is defined at torch/tensor.py:40.

Most of Torch's underlying, compute intensive functionality is implemented in C and C++, including Tensor. "class Tensor" is based on Torch._C.TensorBase which is provided to Python via a C API from torch/csrc/autograd/python_variable.cpp:812

THPVariableType is a map given to Python describing the C++ functions available on the object from Python. It's defined at torch/csrc/autograd/python_variable. The part relevant to you is the tp_as_mapping entry (line 752), which provides functions for objects implementing the mapping protocol - basically Pyton Array-like objects (Python Documentation)

The THPVariable_as_mapping structure at line 725 provides the mapping methods.The second variable provides the a subscript function used to get items by index (Python documentation)

Therefore, The C++ function TPHVariable_getitem provides the implementation of Torch.Tensor.item(), and it is defined at torch/csrc/autograd/python_variable_indexing

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