thrust::replace_copy_if

Defined in thrust/replace.h

template<typename DerivedPolicy, typename InputIterator1, typename InputIterator2, typename OutputIterator, typename Predicate, typename T> OutputIterator thrust::replace_copy_if(const thrust::detail::execution_policy_base<DerivedPolicy> &exec, InputIterator1 first, InputIterator1 last, InputIterator2 stencil, OutputIterator result, Predicate pred, const T &new_value)

This version of replace_copy_if copies elements from the range [first, last) to the range [result, result + (last-first)), except that any element whose corresponding stencil element causes pred to be true is not copied; new_value is copied instead.

More precisely, for every integer n such that 0 <= n < last-first, replace_copy_if performs the assignment *(result+n) = new_value if pred(*(stencil+n)), and *(result+n) = *(first+n) otherwise.

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

#include <thrust/replace.h>
#include <thrust/device_vector.h>
#include <thrust/execution_policy.h>

struct is_less_than_zero
{
  __host__ __device__
  bool operator()(int x)
  {
    return x < 0;
  }
};

...

thrust::device_vector<int> A(4);
A[0] =  10;
A[1] =  20;
A[2] =  30;
A[3] =  40;

thrust::device_vector<int> S(4);
S[0] = -1;
S[1] =  0;
S[2] = -1;
S[3] =  0;

thrust::device_vector<int> B(4);
is_less_than_zero pred;

thrust::replace_if(thrust::device, A.begin(), A.end(), S.begin(), B.begin(), pred, 0);

// B contains [0, 20, 0, 40]