thrust::set_difference

Defined in thrust/set_operations.h

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

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

In the simplest case, set_difference performs the “difference” operation from set theory: the output range contains a copy of every element that is contained in [first1, last1) and not contained in [first2, last1). 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, the last max(m-n,0) elements from [first1, last1) range shall be copied to the output range.

This version of set_difference 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_difference to compute the set difference of two sets of integers sorted in descending 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] = {9, 6, 5, 4, 3, 1, 0};
int A2[5] = {9, 7, 5, 3, 1};

int result[3];

int *result_end = thrust::set_difference(thrust::host, A1, A1 + 7, A2, A2 + 5, result, thrust::greater<int>());
// result is now {6, 4, 0}

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.