Finding and deleting unique values ​​in a vector for a specific tuple field

You can use a combination of the erase vector erase with the standard std::unique algorithm. (If you want to place the result in another vector or container, then you can use the algorithm std::unique_copy ).

For example,

 drv.erase( std::unique( std::begin( drv ), std::end( drv ), []( const auto &a, const auto &b ) { return std::get<4>( a ) == std::get<4>( b ); } ), std::end( drv ) ); 

Below is a demonstration program.

 #include <iostream> #include <iomanip> #include <string> #include <tuple> #include <vector> #include <iterator> #include <algorithm> #include <ctime> typedef unsigned long ULONG; int main() { std::vector<std::tuple<ULONG, ULONG, ULONG, time_t, std::wstring, int>> drv = { { 056, 2328, 94, 1545877351, L"Sasha", 15 }, { 2057, 2328, 94, 1545877351, L"Masha", 15 }, { 2057, 2328, 94, 1545877353, L"Dasha", 15 }, { 2058, 2328, 94, 1545877353, L"Sasha", 15 }, { 2059, 2328, 94, 1545877354, L"Misha", 15 }, { 2059, 2328, 94, 1545877354, L"Misha", 15 } }; for ( const auto &item : drv ) { std::wcout << std::setw( 4 ) << std::get<0>( item ) << ", " << std::setw( 4 ) << std::get<1>( item ) << ", " << std::setw( 2 ) << std::get<2>( item ) << ", " << std::get<3>( item ) << ". " << std::get<4>( item ) << ", " << std::get<5>( item ) << '\n'; } std::wcout << '\n'; std::sort( std::begin( drv ), std::end( drv ), []( const auto &a, const auto &b ) { return std::get<4>( a ) < std::get<4>( b ); } ); drv.erase( std::unique( std::begin( drv ), std::end( drv ), []( const auto &a, const auto &b ) { return std::get<4>( a ) == std::get<4>( b ); } ), std::end( drv ) ); for ( const auto &item : drv ) { std::wcout << std::setw( 4 ) << std::get<0>( item ) << ", " << std::setw( 4 ) << std::get<1>( item ) << ", " << std::setw( 2 ) << std::get<2>( item ) << ", " << std::get<3>( item ) << ". " << std::get<4>( item ) << ", " << std::get<5>( item ) << '\n'; } return 0; } 

Its output to the console:

  46, 2328, 94, 1545877351. Sasha, 15 2057, 2328, 94, 1545877351. Masha, 15 2057, 2328, 94, 1545877353. Dasha, 15 2058, 2328, 94, 1545877353. Sasha, 15 2059, 2328, 94, 1545877354. Misha, 15 2059, 2328, 94, 1545877354. Misha, 15 2057, 2328, 94, 1545877353. Dasha, 15 2057, 2328, 94, 1545877351. Masha, 15 2059, 2328, 94, 1545877354. Misha, 15 46, 2328, 94, 1545877351. Sasha, 15 

On the other hand, perhaps you should immediately choose another container, such as std::set or std::unordered_set .

Below is a demo program that shows how you can select only the unique elements of the source vector in the set std::set without changing the vector itself.

 #include <iostream> #include <iomanip> #include <string> #include <tuple> #include <vector> #include <set> #include <iterator> #include <algorithm> #include <ctime> typedef unsigned long ULONG; int main() { std::vector<std::tuple<ULONG, ULONG, ULONG, time_t, std::wstring, int>> drv = { { 056, 2328, 94, 1545877351, L"Sasha", 15 }, { 2057, 2328, 94, 1545877351, L"Masha", 15 }, { 2057, 2328, 94, 1545877353, L"Dasha", 15 }, { 2058, 2328, 94, 1545877353, L"Sasha", 15 }, { 2059, 2328, 94, 1545877354, L"Misha", 15 }, { 2059, 2328, 94, 1545877354, L"Misha", 15 } }; for ( const auto &item : drv ) { std::wcout << std::setw( 4 ) << std::get<0>( item ) << ", " << std::setw( 4 ) << std::get<1>( item ) << ", " << std::setw( 2 ) << std::get<2>( item ) << ", " << std::get<3>( item ) << ". " << std::get<4>( item ) << ", " << std::get<5>( item ) << '\n'; } std::wcout << '\n'; auto cmp = []( const auto &a, const auto &b ) { return std::get<4>( a ) < std::get<4>( b ); }; std::set<std::tuple<ULONG, ULONG, ULONG, time_t, std::wstring, int>, decltype( cmp )> tuple_set( cmp ); tuple_set.insert( std::begin( drv ), std::end( drv ) ); for ( const auto &item : tuple_set ) { std::wcout << std::setw( 4 ) << std::get<0>( item ) << ", " << std::setw( 4 ) << std::get<1>( item ) << ", " << std::setw( 2 ) << std::get<2>( item ) << ", " << std::get<3>( item ) << ". " << std::get<4>( item ) << ", " << std::get<5>( item ) << '\n'; } std::wcout << '\n'; return 0; } 

The output of the program to the console:

  46, 2328, 94, 1545877351. Sasha, 15 2057, 2328, 94, 1545877351. Masha, 15 2057, 2328, 94, 1545877353. Dasha, 15 2058, 2328, 94, 1545877353. Sasha, 15 2059, 2328, 94, 1545877354. Misha, 15 2059, 2328, 94, 1545877354. Misha, 15 2057, 2328, 94, 1545877353. Dasha, 15 2057, 2328, 94, 1545877351. Masha, 15 2059, 2328, 94, 1545877354. Misha, 15 46, 2328, 94, 1545877351. Sasha, 15 

Use std::unique() and binary predicate using your sortbyPath() function:

 template< class ExecutionPolicy, class ForwardIt, class BinaryPredicate > ForwardIt unique( ExecutionPolicy&& policy, ForwardIt first, ForwardIt last, BinaryPredicate p ); 

The code may end up with something like this:

 std::sort( drv.begin(), drv.end(), sortbyPath ); auto it = std::unique( drv.begin(), drv.end(), []( const auto &a, const auto &b ) { return not sortbyPath( a, b ) and not sortByPath( b, a ); } ); drv.erase( it, drv.end() ); 

Or you can write another function equalByPath() , which will create duplicate code, but will most likely be more efficient.

If you sort only to leave unique ones, then it is not necessary to do this, it is simpler to use std::unordered_set and std::remove_if :

 std::unordered_set<std::wstring> uset; // тут была ошибка unoredered_set вместо unordered_set auto it = std::remove_if( drv.begin(), drv.end(), [&uset]( const auto &d ) { return not uset.insert( std::get<4>( d ) ).second; } ); drv.erase( it, drv.end() );