Index Sort: Example and Test
Keywords: index sort: example test index_sort

| Prev | Next |  |  |  |  |  | index_sort.cpp | Headings

Index Sort: Example and Test
`

    # include <cppad/utility/index_sort.hpp>
    # include <cppad/utility/vector.hpp>
    # include <valarray>
    # include <vector>

    namespace{
    	// class that uses < to compare a pair of size_t values
    	class Key {
    	public:
    		size_t first_;
    		size_t second_;
    		//
    		Key(void)
    		{ }
    		//
    		Key(size_t first, size_t second)
    		: first_(first), second_(second)
    		{ }
    		//
    		bool operator<(const Key& other) const
    		{	if( first_ == other.first_ )
    				return second_ < other.second_;
    			return first_ < other.first_;
    		}
    	};

    	template <class VectorKey, class VectorSize>
    	bool vector_case(void)
    	{	bool ok = true;
    		size_t i, j;
    		size_t first[]  =  { 4, 4, 3, 3, 2, 2, 1, 1};
    		size_t second[] = { 0, 1, 0, 1, 0, 1, 0, 1};
    		size_t size     = sizeof(first) / sizeof(first[0]);

    		VectorKey keys(size);
    		for(i = 0; i < size; i++)
    			keys[i] = Key(first[i], second[i]);

    		VectorSize ind(size);
    		CppAD::index_sort(keys, ind);

    		// check that all the indices are different
    		for(i = 0; i < size; i++)
    		{	for(j = 0; j < size; j++)
    				ok &= (i == j) | (ind[i] != ind[j]);
    		}

    		// check for increasing order
    		for(i = 0; i < size-1; i++)
    		{	if( first[ ind[i] ] == first[ ind[i+1] ] )
    				ok &= second[ ind[i] ] <= second[ ind[i+1] ];
    			else	ok &= first[ ind[i] ] < first[ ind[i+1] ];
    		}

    		return ok;
    	}
    }

    bool index_sort(void)
    {	bool ok = true;

    	// some example simple vector template classes
    	ok &= vector_case<  std::vector<Key>,  std::valarray<size_t> >();
    	ok &= vector_case< std::valarray<Key>, CppAD::vector<size_t> >();
    	ok &= vector_case< CppAD::vector<Key>,   std::vector<size_t> >();

    	return ok;
    }

`

Input File: example/index_sort.cpp