thrust::set_union

Defined in thrust/set_operations.h

template<typename DerivedPolicy, typename InputIterator1, typename InputIterator2, typename OutputIterator, typename StrictWeakCompare>
OutputIterator thrust::set_union(const thrust::detail::execution_policy_base<DerivedPolicy> &exec, InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator result, StrictWeakCompare comp)

set_union constructs a sorted range that is the union of the sorted ranges [first1, last1) and [first2, last2). The return value is the end of the output range.

In the simplest case, set_union performs the “union” operation from set theory: the output range contains a copy of every element that is contained in [first1, last1), [first2, last1), or both. The general case is more complicated, because the input ranges may contain duplicate elements. The generalization is that if [first1, last1) contains m elements that are equivalent to each other and if [first2, last2) contains n elements that are equivalent to them, then all m elements from the first range shall be copied to the output range, in order, and then max(n - m, 0) elements from the second range shall be copied to the output, in order.

This version of set_union compares elements using a function object comp.

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

The following code snippet demonstrates how to use set_union to compute the union of two sets of integers sorted in ascending order using the thrust::host execution policy for parallelization:

#include <thrust/set_operations.h>
#include <thrust/functional.h>
#include <thrust/execution_policy.h>
...
int A1[7] = {12, 10, 8, 6, 4, 2, 0};
int A2[5] = {9, 7, 5, 3, 1};

int result[11];

int *result_end = thrust::set_union(thrust::host, A1, A1 + 7, A2, A2 + 5, result, thrust::greater<int>());
// result = {12, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0}

See also

https://en.cppreference.com/w/cpp/algorithm/set_union

See also

merge

See also

includes

See also

set_union

See also

set_intersection

See also

set_symmetric_difference

See also

sort

See also

is_sorted

Parameters

  • exec – The execution policy to use for parallelization.

  • first1 – The beginning of the first input range.

  • last1 – The end of the first input range.

  • first2 – The beginning of the second input range.

  • last2 – The end of the second input range.

  • result – The beginning of the output range.

  • comp – Comparison operator.

Template Parameters

  • DerivedPolicy – The name of the derived execution policy.

  • InputIterator1 – is a model of Input Iterator, InputIterator1's value_type is convertible to StrictWeakCompare's first_argument_type. and InputIterator1's value_type is convertible to a type in OutputIterator's set of value_types.

  • InputIterator2 – is a model of Input Iterator, InputIterator2's value_type is convertible to StrictWeakCompare's second_argument_type. and InputIterator2's value_type is convertible to a type in OutputIterator's set of value_types.

  • OutputIterator – is a model of Output Iterator.

  • StrictWeakCompare – is a model of Strict Weak Ordering.

Returns

The end of the output range.

Pre

The ranges [first1, last1) and [first2, last2) shall be sorted with respect to comp.

Pre

The resulting range shall not overlap with either input range.