thrust::partition_copy

Defined in thrust/partition.h

template<typename DerivedPolicy, typename InputIterator, typename OutputIterator1, typename OutputIterator2, typename Predicate> thrust::pair<OutputIterator1, OutputIterator2> thrust::partition_copy(const thrust::detail::execution_policy_base<DerivedPolicy> &exec, InputIterator first, InputIterator last, OutputIterator1 out_true, OutputIterator2 out_false, Predicate pred)

partition_copy differs from partition only in that the reordered sequence is written to different output sequences, rather than in place.

partition_copy copies the elements [first, last) based on the function object pred. All of the elements that satisfy pred are copied to the range beginning at out_true and all the elements that fail to satisfy it are copied to the range beginning at out_false.

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

The following code snippet demonstrates how to use partition_copy to separate a sequence into two output sequences of even and odd numbers using the thrust::host execution policy for parallelization:

#include <thrust/partition.h>
#include <thrust/execution_policy.h>
...
struct is_even
{
  __host__ __device__
  bool operator()(const int &x)
  {
    return (x % 2) == 0;
  }
};
...
int A[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
int result[10];
const int N = sizeof(A)/sizeof(int);
int *evens = result;
int *odds  = result + 5;
thrust::partition_copy(thrust::host, A, A + N, evens, odds, is_even());
// A remains {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
// result is now {2, 4, 6, 8, 10, 1, 3, 5, 7, 9}
// evens points to {2, 4, 6, 8, 10}
// odds points to {1, 3, 5, 7, 9}