Question

我的XYZ位置为1000点。我需要用矩阵对其进行变换。首先，从一个简单的问题开始，我尝试将每个点乘以一个常数。我也只举三点。我使用推力:: zip_iterator打包XYZ，并使用函子和变换操作来修改XYZ。

我的代码如下，但是它给出了编译错误。函子Modify_tuple可以正常编译。但是，在转换操作中使用它时，我会遇到很多错误。 我的问题是如何修改zip迭代器的内容？或如何使用推力将函子应用于所有点的XYZ类型的元组。我还可以使用其他推力算法吗？

#include <thrust/transform.h>
#include <thrust/iterator/zip_iterator.h>
#include <thrust/execution_policy.h>

typedef thrust::tuple<float,float,float> Float3;

struct modify_tuple
{
    int _factor;
    modify_tuple(int factor) : _factor(factor) { }

    __host__ __device__ Float3 operator()(Float3&a) const
    {
        Float3 b=thrust::make_tuple(_factor*thrust::get<0>(a), _factor*thrust::get<1>(a), _factor*thrust::get<2>(a));      

        return b;
    }
};

int main(void)
{
    thrust::device_vector<float> X(3);
    thrust::device_vector<float> Y(3);
    thrust::device_vector<float> Z(3);

    X[0]=0,    X[0]=1,    X[0]=2;
    Y[0]=4,    Y[0]=5,    Y[0]=6;
    Z[0]=7,    Z[0]=8,    Z[0]=9;

    typedef thrust::device_vector<float>::iterator                     FloatIterator;
    typedef thrust::tuple<FloatIterator, FloatIterator, FloatIterator> FloatIteratorTuple;
    typedef thrust::zip_iterator<FloatIteratorTuple>                   Float3Iterator;

    Float3Iterator P_first = thrust::make_zip_iterator(make_tuple(X.begin(), Y.begin(), Z.begin()));
    Float3Iterator P_last  = thrust::make_zip_iterator(make_tuple(X.end(), Y.end(), Z.end()));

// This line gives errors
    thrust::transform(thrust::device, P_first, P_last, P_first, modify_tuple(2));  

    return 0;
}

在编译过程中发现错误：

/usr/local/cuda/bin/../targets/x86_64-linux/include/thrust/detail/internal_functional.h(322): error: function "modify_tuple::operator()" cannot be called with the given argument list
            argument types are: (thrust::detail::tuple_of_iterator_references<float &, float &, float &, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>)
            object type is: modify_tuple
          detected during:
            instantiation of "thrust::detail::enable_if_non_const_reference_or_tuple_of_iterator_references<thrust::tuple_element<1, Tuple>::type>::type thrust::detail::unary_transform_functor<UnaryFunction>::operator()(Tuple) [with UnaryFunction=modify_tuple, Tuple=thrust::detail::tuple_of_iterator_references<thrust::detail::tuple_of_iterator_references<float &, float &, float &, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>, thrust::detail::tuple_of_iterator_references<float &, float &, float &, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>]" 
/usr/local/cuda/bin/../targets/x86_64-linux/include/thrust/detail/function.h(60): here
            instantiation of "Result thrust::detail::wrapped_function<Function, Result>::operator()(const Argument &) const [with Function=thrust::detail::unary_transform_functor<modify_tuple>, Result=void, Argument=thrust::detail::tuple_of_iterator_references<thrust::detail::tuple_of_iterator_references<thrust::device_reference<float>, thrust::device_reference<float>, thrust::device_reference<float>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>, thrust::detail::tuple_of_iterator_references<thrust::device_reference<float>, thrust::device_reference<float>, thrust::device_reference<float>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>]" 
/usr/local/cuda/bin/../targets/x86_64-linux/include/thrust/system/cuda/detail/for_each.inl(57): here
            instantiation of "void thrust::system::cuda::detail::for_each_n_detail::for_each_kernel::operator()(thrust::system::cuda::detail::bulk_::parallel_group<thrust::system::cuda::detail::bulk_::concurrent_group<thrust::system::cuda::detail::bulk_::agent<1UL>, 0UL>, 0UL> &, Iterator, Function, Size) [with Iterator=thrust::zip_iterator<thrust::tuple<thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, Function=thrust::detail::wrapped_function<thrust::detail::unary_transform_functor<modify_tuple>, void>, Size=unsigned int]" 
/usr/local/cuda/bin/../targets/x86_64-linux/include/thrust/system/cuda/detail/bulk/detail/apply_from_tuple.hpp(71): here
            instantiation of "void thrust::system::cuda::detail::bulk_::detail::apply_from_tuple(Function, const thrust::tuple<Arg1, Arg2, Arg3, Arg4, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type> &) [with Function=thrust::system::cuda::detail::for_each_n_detail::for_each_kernel, Arg1=thrust::system::cuda::detail::bulk_::parallel_group<thrust::system::cuda::detail::bulk_::concurrent_group<thrust::system::cuda::detail::bulk_::agent<1UL>, 0UL>, 0UL> &, Arg2=thrust::zip_iterator<thrust::tuple<thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, Arg3=thrust::detail::wrapped_function<thrust::detail::unary_transform_functor<modify_tuple>, void>, Arg4=unsigned int]" 
/usr/local/cuda/bin/../targets/x86_64-linux/include/thrust/system/cuda/detail/bulk/detail/closure.hpp(50): here
            instantiation of "void thrust::system::cuda::detail::bulk_::detail::closure<Function, Tuple>::operator()() [with Function=thrust::system::cuda::detail::for_each_n_detail::for_each_kernel, Tuple=thrust::tuple<thrust::system::cuda::detail::bulk_::parallel_group<thrust::system::cuda::detail::bulk_::concurrent_group<thrust::system::cuda::detail::bulk_::agent<1UL>, 0UL>, 0UL> &, thrust::zip_iterator<thrust::tuple<thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, thrust::detail::wrapped_function<thrust::detail::unary_transform_functor<modify_tuple>, void>, unsigned int, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>]" 
/usr/local/cuda/bin/../targets/x86_64-linux/include/thrust/system/cuda/detail/bulk/detail/cuda_task.hpp(58): here
            [ 8 instantiation contexts not shown ]
            instantiation of "RandomAccessIterator thrust::system::cuda::detail::for_each_n(thrust::system::cuda::detail::execution_policy<DerivedPolicy> &, RandomAccessIterator, Size, UnaryFunction) [with DerivedPolicy=thrust::system::cuda::detail::par_t, RandomAccessIterator=thrust::zip_iterator<thrust::tuple<thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, Size=signed long, UnaryFunction=thrust::detail::unary_transform_functor<modify_tuple>]" 
/usr/local/cuda/bin/../targets/x86_64-linux/include/thrust/system/cuda/detail/for_each.inl(173): here
            instantiation of "RandomAccessIterator thrust::system::cuda::detail::for_each(thrust::system::cuda::detail::execution_policy<DerivedPolicy> &, RandomAccessIterator, RandomAccessIterator, UnaryFunction) [with DerivedPolicy=thrust::system::cuda::detail::par_t, RandomAccessIterator=thrust::zip_iterator<thrust::tuple<thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, UnaryFunction=thrust::detail::unary_transform_functor<modify_tuple>]" 
/usr/local/cuda/bin/../targets/x86_64-linux/include/thrust/detail/for_each.inl(44): here
            instantiation of "InputIterator thrust::for_each(const thrust::detail::execution_policy_base<DerivedPolicy> &, InputIterator, InputIterator, UnaryFunction) [with DerivedPolicy=thrust::system::cuda::detail::par_t, InputIterator=thrust::zip_iterator<thrust::tuple<thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, UnaryFunction=thrust::detail::unary_transform_functor<modify_tuple>]" 
/usr/local/cuda/bin/../targets/x86_64-linux/include/thrust/system/detail/generic/transform.inl(57): here
            instantiation of "OutputIterator thrust::system::detail::generic::transform(thrust::execution_policy<DerivedPolicy> &, InputIterator, InputIterator, OutputIterator, UnaryFunction) [with DerivedPolicy=thrust::system::cuda::detail::par_t, InputIterator=thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, OutputIterator=thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, UnaryFunction=modify_tuple]" 
/usr/local/cuda/bin/../targets/x86_64-linux/include/thrust/detail/transform.inl(44): here
            instantiation of "OutputIterator thrust::transform(const thrust::detail::execution_policy_base<DerivedPolicy> &, InputIterator, InputIterator, OutputIterator, UnaryFunction) [with DerivedPolicy=thrust::system::cuda::detail::par_t, InputIterator=thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, OutputIterator=thrust::zip_iterator<thrust::tuple<thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::detail::normal_iterator<thrust::device_ptr<float>>, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type, thrust::null_type>>, UnaryFunction=modify_tuple]" 
modify_zip_iterator.cu(38): here

Answer 1

获取函子类型以匹配推力传递的类型和推力所需的类型有时会很棘手。这是一种使用模板的方法，可以让编译器确定所需的确切类型：

$ cat t334.cu
#include <thrust/transform.h>
#include <thrust/iterator/zip_iterator.h>
#include <thrust/execution_policy.h>
#include <iostream>
#include <thrust/copy.h>

struct modify_tuple
{
    int _factor;
    modify_tuple(int factor) : _factor(factor) { }
template <typename T>
    __host__ __device__ thrust::tuple<float,float,float> operator()(const T a) const
    {
        thrust::tuple<float,float,float>  res = a;
        thrust::get<0>(res) *= _factor;
        thrust::get<1>(res) *= _factor;
        thrust::get<2>(res) *= _factor;
        return res;
    }
};

int main(void)
{
    thrust::device_vector<float> X(3);
    thrust::device_vector<float> Y(3);
    thrust::device_vector<float> Z(3);
    thrust::device_vector<float> RX(3);
    thrust::device_vector<float> RY(3);
    thrust::device_vector<float> RZ(3);

    X[0]=0,    X[1]=1,    X[2]=2;
    Y[0]=4,    Y[1]=5,    Y[2]=6;
    Z[0]=7,    Z[1]=8,    Z[2]=9;

    thrust::copy_n(X.begin(), 3, std::ostream_iterator<float>(std::cout, ","));
    std::cout << std::endl;
    thrust::copy_n(Y.begin(), 3, std::ostream_iterator<float>(std::cout, ","));
    std::cout << std::endl;
    thrust::copy_n(Z.begin(), 3, std::ostream_iterator<float>(std::cout, ","));
    std::cout << std::endl;
    thrust::transform(thrust::device, thrust::make_zip_iterator(thrust::make_tuple(X.begin(), Y.begin(), Z.begin())),thrust::make_zip_iterator(thrust::make_tuple(X.end(), Y.end(), Z.end())), thrust::make_zip_iterator(thrust::make_tuple(RX.begin(), RY.begin(), RZ.begin())), modify_tuple(2));
    thrust::copy_n(X.begin(), 3, std::ostream_iterator<float>(std::cout, ","));
    std::cout << std::endl;
    thrust::copy_n(Y.begin(), 3, std::ostream_iterator<float>(std::cout, ","));
    std::cout << std::endl;
    thrust::copy_n(Z.begin(), 3, std::ostream_iterator<float>(std::cout, ","));
    std::cout << std::endl;
    thrust::copy_n(RX.begin(), 3, std::ostream_iterator<float>(std::cout, ","));
    std::cout << std::endl;
    thrust::copy_n(RY.begin(), 3, std::ostream_iterator<float>(std::cout, ","));
    std::cout << std::endl;
    thrust::copy_n(RZ.begin(), 3, std::ostream_iterator<float>(std::cout, ","));
    std::cout << std::endl;

    return 0;
}
$ nvcc -o t334 t334.cu
$ ./t334
0,1,2,
4,5,6,
7,8,9,
0,1,2,
4,5,6,
7,8,9,
0,2,4,
8,10,12,
14,16,18,
$

传递给函子的确切基础类型似乎是迭代器元组引用，而返回类型是具有float值的普通元组。

请注意，可以直接在函子中修改a。通常看来，a是按值传递给函子的，但是在这种情况下，推力使用的是迭代器元组引用，因此在函子中修改a的副作用是它将修改传递给函子的实际推力矢量值（即源矢量）。因此，我在上面的代码中选择了一种避免这种情况的实现，但是对于您的原始代码，很明显，您打算对源向量进行就地修改。因此，如果需要，可以简化函子以直接直接修改a。

如何修改zip迭代器的内容

1 个答案: