thrust::scatter_if

Defined in thrust/scatter.h

template<typename DerivedPolicy, typename InputIterator1, typename InputIterator2, typename InputIterator3, typename RandomAccessIterator>
void thrust::scatter_if(const thrust::detail::execution_policy_base<DerivedPolicy> &exec, InputIterator1 first, InputIterator1 last, InputIterator2 map, InputIterator3 stencil, RandomAccessIterator output)

scatter_if conditionally copies elements from a source range into an output array according to a map. For each iterator i in the range [first, last) such that *(stencil + (i - first)) is true, the value *i is assigned to output[*(map + (i - first))]. The output iterator must permit random access. If the same index appears more than once in the range [map, map + (last - first)) the result is undefined.

The algorithm’s execution is parallelized as determined by exec.

#include <thrust/scatter.h>
#include <thrust/execution_policy.h>
...
int V[8] = {10, 20, 30, 40, 50, 60, 70, 80};
int M[8] = {0, 5, 1, 6, 2, 7, 3, 4};
int S[8] = {1, 0, 1, 0, 1, 0, 1, 0};
int D[8] = {0, 0, 0, 0, 0, 0, 0, 0};

thrust::scatter_if(thrust::host, V, V + 8, M, S, D);

// D contains [10, 30, 50, 70, 0, 0, 0, 0];

Note

scatter_if is the inverse of thrust::gather_if.

Parameters

  • exec – The execution policy to use for parallelization.

  • first – Beginning of the sequence of values to scatter.

  • last – End of the sequence of values to scatter.

  • map – Beginning of the sequence of output indices.

  • stencil – Beginning of the sequence of predicate values.

  • output – Beginning of the destination range.

Template Parameters

  • DerivedPolicy – The name of the derived execution policy.

  • InputIterator1 – must be a model of Input Iterator and InputIterator1's value_type must be convertible to RandomAccessIterator's value_type.

  • InputIterator2 – must be a model of Input Iterator and InputIterator2's value_type must be convertible to RandomAccessIterator's difference_type.

  • InputIterator3 – must be a model of Input Iterator and InputIterator3's value_type must be convertible to bool.

  • RandomAccessIterator – must be a model of Random Access iterator.

Pre

The iterator result + i shall not refer to any element referenced by any iterator j in the range [first,last) for all iterators i in the range [map,map + (last - first)).

Pre

The iterator result + i shall not refer to any element referenced by any iterator j in the range [map,map + (last - first)) for all iterators i in the range [map,map + (last - first)).

Pre

The iterator result + i shall not refer to any element referenced by any iterator j in the range [stencil,stencil + (last - first)) for all iterators i in the range [map,map + (last - first)).

Pre

The expression result[*i] shall be valid for all iterators i in the range [map,map + (last - first)) for which the following condition holds: *(stencil + i) != false.