Uninitialised output 'argsort'

[tdegeus]

This

#include <xtensor.hpp>

int main()
{
    xt::xtensor<double, 2> A = {{1.0, 1.0, 1.0, 1.0}};
    auto isort = xt::argsort(A, 1);
    std::cout << isort << std::endl;

    return 0;
}

gives incorrect output:

{{0, 0, 0, 0}}

while

#include <xtensor.hpp>

int main()
{
    xt::xtensor<double, 2> A = {{1.0, 1.0, 1.0, 1.0},
                                {1.4, 1.3, 1.2, 1.1}};
    auto isort = xt::argsort(A, 1);
    std::cout << isort << std::endl;

    return 0;
}

does give reasonable output:

{{0, 1, 2, 3},
 {3, 2, 1, 0}}

---

Also in my original problem:

    auto eps = GM::Epsd(this->plastic_Eps());
    auto epsy = this->plastic_CurrentYieldRight();
    std::cout << eps << std::endl;
    std::cout << epsy << std::endl;
    std::cout << xt::adapt(eps.shape()) << std::endl;
    std::cout << xt::adapt(epsy.shape()) << std::endl;
    auto deps = xt::eval(epsy - eps);
    auto isort = xt::argsort(deps, 1);
    std::cout << deps << std::endl;
    std::cout << isort << std::endl;

I'm getting

{{ 0.,  0.,  0.,  0.}}
{{ 1.,  1.,  1.,  1.}}
{1, 4}
{1, 4}
{{ 1.,  1.,  1.,  1.}}
{{13835058055282163712, 13835058055282163712, 4, 0}}

[tdegeus]

See #2238

[ImNotMT]

so far still not fixed. this bug is caused the following (for argsort(axis=1)):
when xarray.shape(0) is 1, both data_secondary_stride and inds_secondary_strideis would be 0.
the following functions will not do anything since range from indices_ptr to indices_ptr + 0 is 0.
std::iota(indices_ptr, indices_ptr + inds_secondary_stride, 0);
std::sort(indices_ptr, indices_ptr + inds_secondary_stride, comp);

for walk around, I have to flatten input xarray first if its shape(0) is 1, and add newaxis to the output of argsort.