struct arraySizeTwoEqualityStruct

bool operator()( const array< double, 2 >& leftArraySizeTwo,
                 const array< double, 2 >& rightArraySizeTwo ) const
{

    return
            abs( leftArraySizeTwo[ 0 ] - rightArraySizeTwo[ 0 ] ) < 0.0001 &&
            abs( leftArraySizeTwo[ 1 ] - rightArraySizeTwo[ 1 ] ) < 0.0001;

}

struct arraySizeTwoHashStruct

size_t operator( )( const array< double, 2 >& arrayToHash ) const
{

    return ( hash< double > ( ) ( arrayToHash[ 0 ] ) ^ hash< double > ( ) ( arrayToHash[ 1 ] ) );

}

bool potentialNodeDuplicate( array< double, 2 > & possibleDuplicateValuesArgument,
                         int parentReferenceArgument,
                         double edgeWeightArgument,
                         unordered_map< array< double, 2 >, int, arraySizeTwoHashStruct, arraySizeTwoEqualityStruct > possibleDuplicateReferencesArgument,
                         vector< pair< vehicleNode, vector< nodeEdge > > >& adjacencyListArgument )

if ( possibleDuplicateReferencesArgument.find( possibleDuplicateValuesArgument ) != possibleDuplicateReferencesArgument.end() )
    {

...
    }