Is there any combination to implement signcopy?

C++
1

Hi, Dear forum:
I want to get the signbit of a tensor. Pytorch provide a sign() function, however, it return 0 for zero. Is any way to return 1 if 0 and pos, otherwise -1? I only want [1, -1] rather [1, 0, -1].

2

Hi @singleroc,

this should give you what you want

float arr[] = {-1, 0, 1};
auto data = torch::from_blob(arr, 3);
auto sizes = data.sizes();

auto sign = torch::ones(sizes).where(data.ge(torch::zeros(sizes)), torch::full(sizes, -1));

std::cout << sign << std::endl;
3

Hi, dear @mhubii

Thanks for your answer. The code seems to be C++ version. Today I come up with an idea with python:

def get_copysign(x): 
    y = x.sign()
    y.masked_fill_(x == 0, 1) 
    return y
4

hm yes because this is the c++ channel of the forum :see_no_evil::grin: