thrust::set_union

Defined in thrust/set_operations.h

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

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 operator<.

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

int result[11];

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

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.

Template Parameters

DerivedPolicy – The name of the derived execution policy.
InputIterator1 – is a model of Input Iterator, InputIterator1 and InputIterator2 have the same value_type, InputIterator1's value_type is a model of LessThan Comparable, the ordering on InputIterator1's value_type is a strict weak ordering, as defined in the LessThan Comparable requirements, 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 and InputIterator1 have the same value_type, InputIterator2's value_type is a model of LessThan Comparable, the ordering on InputIterator2's value_type is a strict weak ordering, as defined in the LessThan Comparable requirements, and InputIterator2's value_type is convertible to a type in OutputIterator's set of value_types.
OutputIterator – is a model of Output Iterator.

Returns

The end of the output range.

Pre

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

Pre

The resulting range shall not overlap with either input range.