/* linbox/blackbox/zo.h
 * Copyright (c) LinBox
 * by Hui Wang, assisted by bds
 * ------------------------------------
 * 
 * ========LICENCE========
 * This file is part of the library LinBox.
 * 
 * LinBox is free software: you can redistribute it and/or modify
 * it under the terms of the  GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * ========LICENCE========
 *.
 */

#ifndef __LINBOX_zero_one_H
#define __LINBOX_zero_one_H

/*! @file blackbox/zo.h
 * We define a blackbox class of the same name as that in zero-one.h,
 * hence we use the same name here.
 * @warning The two cannot be used in the same prog.
 */


#include "linbox/integer.h"
//#include "linbox/vector/vector-traits.h"
#include "linbox/util/debug.h"
#include "linbox/util/matrix-stream.h"
#include "linbox/field/modular.h"
#include "linbox/blackbox/blackbox-interface.h"
#include "linbox/blackbox/quad-matrix.h"

// For STL pair in IndexIterator
#include <utility>
#include <iterator>
#include <vector> // For vectors in _col2row and _row2col
#include <cstdlib> // For randomness in randomized quicksort
#include <ctime>

namespace LinBox
{
	bool revLexLess(const std::pair<size_t,size_t>& a, const std::pair<size_t,size_t> b)
	{ return a.second < b.second || (b.second == a.second && a.first < b.first); }

	/** \brief Time and space efficient representation of sparse {0,1}-matrices.
	 *
	 * A 0-1 matrix is a matrix with all 0's and 1's as entries.
	 * We're using a comp-col or comp-row format.  That is we have an array of col indices and an array of pointers indicating where the col indices for each row begins within the col index array.  (or vice versa if we have sorted by columns.
	 *
	 * Applies can be performed fast, using only additions.
	 * When initalizing this class, you only need to build 2 arrays of equal length:
	 * an array of the row indices for the non-zero (1's) entries, and an array of the column
	 * indices for the non-zero (1's) entries.

	 A {0, 1,-1} matrix can be effecively represented as the \ref Dif of two ZeroOne's.
	 \ingroup blackbox
	 */

	template<class _Field>
	class ZeroOne : public BlackboxInterface {
	public:
		//friend class ZOQuad;

		typedef size_t Index;
		typedef ZeroOne<_Field> Self_t;
		typedef _Field Field;
		typedef typename _Field::Element Element;
		typedef std::vector<Index> IndexVector;
		typedef std::vector<IndexVector::iterator> PointerVector;
		//to denote by which way we sort our matrix
		enum howToSort { sortedByRow, sortedByCol }; //( true / false )

		// DEFAULT CONSTRUCTOR, do nothing. Matrix will be uninitialized.
		ZeroOne(){};

		// basic constructor, can be used with subsequent read.
		ZeroOne(const Field& F) :
		       	_field(F), sorted(true)
		{}

		// constructor for use by ZOQuad.  Needs work.
		ZeroOne (const Field& F, IndexVector& index, PointerVector& indexP,
			 Index Rowdim, Index Coldim, bool sortedBy) :
			_field(F), _index(index), _indexP(indexP),
			_rowdim(Rowdim), _coldim(Coldim), sorted(sortedBy)
		{
			std::ptrdiff_t diff = _index.begin() - index.begin();
			for (size_t i = 0; i < _indexP.size(); ++i)
				_indexP[i] += diff;

#if 0
			_indexP.push_back( _index.begin() );
			IndexVector::iterator   i = _index.begin();
			PointerVector::iterator j = indexP.begin();
			for( ++j; j < indexP.end(); ++j ) {
				_indexP.push_back( i + ( *j - *(j-1) ) );
				i = _indexP.back();
			}
#endif
		}

		/** The real constructor /todo give docs here
		  assuming entries are sorted in lexicographic order by (row,col) pair.
		  */
		ZeroOne
		(Field& F, Index* rowP, Index* colP, Index rows, Index cols, Index NNz) :
			_field(F), _rowdim(rows), _coldim(cols), sorted(true)
		{
			std::vector<std::pair<Index, Index> > indexPairs;
			for (Index i = 0; i < NNz; ++i, ++rowP, ++colP)
				indexPairs.push_back(std::pair<Index,Index>(static_cast<Index>(*rowP), static_cast<Index>(*colP)));
			init(indexPairs);
		}
		ZeroOne(const ZeroOne<Field>& A) :
			// better keep the commented out statements below for later debugging
			_field(A._field), _index(A._index), _rowdim(A._rowdim), _coldim(A._coldim), sorted(A.sorted)
		{
#if 0
			std::cout << " copy constructor of zero-one matrix: A.rowdim = "  << A._rowdim << " A.coldim = " << A._coldim << std::endl;
			ZeroOne(A._field, A._index, A._indexP, A._rowdim, A._coldim, A.sorted);
			std::cout << " copy constructor of zero-one matrix: rowdim = " << _rowdim << " coldim = " << _coldim << std::endl;
#endif
			_indexP.push_back( _index.begin() );
			IndexVector::iterator i = _index.begin();
			PointerVector::iterator j = A._indexP.begin();
			for( ++j; j < A._indexP.end(); ++j )
			{
				//std::cout << *j - *(j-1) << std::endl;
				_indexP.push_back( i + ( *j - *(j-1) ) );
#if 0
				std::cout << " stupid test here " << (*_indexP.begin()) - _index.begin() << std::endl;
				std::cout << " the size of _indexP now is " << _indexP.size() << std::endl;
#endif
				i = _indexP.back();
#if 0
				std::cout << " the last element points to the position " << _indexP.back() - *_indexP.begin() << std::endl;
#endif
			}
#if 0
			_indexP.push_back(_index.end());
			std::cout << &_index << " ";
			std::cout << &(*_index.begin()) << std::endl;
			std::cout << std::endl;
#endif
		}

		//switching the way in which the matrix is sorted
		void switch_sort() const
		{
			//std::cout << " -- switch_sort: " << std::endl;
			Index dim;

			if( sorted ) dim = _coldim;
			else dim = _rowdim;

			//std::cout << " -- in switch sort, before allocating temp -- " << std::endl;
			std::vector< IndexVector > temp(dim);
			//std::cout << temp.size() << std::endl;
			//IndexVector temp[dim]; //maybe this needs toooooo much memory space when dim is very large
			//std::cout << " -- in switch sort, after allocating temp -- " << std::endl;

			for( PointerVector::iterator i = _indexP.begin(); i < _indexP.end() - 1; ++i )
				for( IndexVector::iterator j = *i; j != *(i+1); ++j )
					temp[*j].push_back( (Index)(i - _indexP.begin()) );

			_index.clear(); _indexP.clear();
			std::back_insert_iterator < std::vector<Index> > colend( _index) ;
			for( size_t k = 0; k < dim; ++k )
			{
				_indexP.push_back( _index.end() );
				copy( temp[k].begin(), temp[k].end(), colend );
			}

			_indexP.push_back( _index.end() );
			sorted = !sorted;

			return;
		}

	protected:

		void init(std::vector<std::pair<Index, Index> >& ip)
		{
			Index NNz = ip.size();
			sort(ip.begin(), ip.end());

			// set up _index
			for (Index i = 0; i < NNz; ++i)
				_index.push_back(ip[i].second);

			// set up _indexP
			IndexVector::iterator p = _index.begin(); //how about if the first row of the matrix is empty
			_indexP.push_back(p);                     //we haven't met this case up to now

			std::vector<std::pair<Index, Index> >::iterator q = ip.begin();
			Index i = q->first;
			p++;q++; //start from the second place

			for (; q != ip.end(); ++q, ++p)
				if (i != q->first)
				{
					//for (Index j = i; j < (q+1)->first; j++)//difference may be more than 1
					for (Index j = i; j < q->first; j++)//difference may be more than 1
						_indexP.push_back(p);
					i = q->first; //we should change i after the for loop, otherwise the
					//for loop will not run at all
				}
			_indexP.push_back(_index.end());

			/* keep another copy is not needed if we can switch sort between row and col
			// sort by cols first, then do the same as above
			sort(ip.begin(), ip.end(), revLexLess);

			// set up _row
			for (Index i = 0; i < NNz; ++i)
			_row.push_back(ip[i].first);

			// set up _colP
			p = _row.begin();
			_colP.push_back(p);

			q =ip.begin();
			i = q->second;
			p++;q++;

			for ( ; q != ip.end(); ++q, ++p)
			if (i != q->second)
			{
			for (Index j = i; j < (q+1)->second; j++)
			_colP.push_back(p);
			i = q->second;
			}
			_colP.push_back(_row.end());
			*/

		}
	public:

		// Destructor, once again do nothing
		~ZeroOne(){};

		/** \brief
		 *
		 * Uses one of the three
		 * private utility functions. It calls the generalized utility function
		 * _apply if there is no special ordering, _fyapply if there is C_ordering
		 * or _fxapply if there is fortran_ordering
		 */
		template<class OutVector, class InVector>
		OutVector& apply(OutVector& y, const InVector& x) const; // y = Ax;
		//OutVector& apply(OutVector& y, const InVector& x); // y = Ax;

		/** \brief
		 *
		 * Uses one of the three
		 * private utility functions, in the manner described above.  Worthy of
		 * note is the fact that applyTranspose works by passing the column
		 * positions to the _apply functions as if they were rows, and row positions
		 * as if they were columns, as if the matrix had been transposed.
		 */

		template<class OutVector, class InVector>
		OutVector& applyTranspose(OutVector& y, const InVector& x) const; // y = ATx
		//OutVector& applyTranspose(OutVector& y, const InVector& x); // y = ATx

		size_t rowdim() const
		{ return _rowdim; }

		size_t coldim() const
		{ return _coldim; }


		template<typename _Tp1>
		struct rebind
		{
			typedef ZeroOne<_Tp1> other;
			void operator() (other *& Ap,
					 const Self_t& A,
					 const _Tp1& F) {
				Ap = new other(F, A._index, A._indexP, A._rowdim, A._coldim, A.sorted);
			}
		};

		/** Read the matrix from a stream in the JGD's SMS format
		 *  @param is Input stream from which to read the matrix
		 *  @return Reference to input stream
		 */
		std::istream &read (std::istream &is)
		{
			std::vector<std::pair<Index, Index> > indexPairs;
			Index r, c;
			Element v;
			MatrixStream<Field> S(_field, is);
			long count = 0;

			// /*
			S.getDimensions( _rowdim, _coldim );
			std::cout << " -- read: row dimension is " << _rowdim << " and column dimension is " <<_coldim << std::endl;
			while (S.nextTriple(r, c, v) )
			{
				indexPairs.push_back(std::pair<Index,Index>(static_cast<Index>(r), static_cast<Index>(c)));
				++count;
			}
			/*
			   char v0;
			   is >> _rowdim >> _coldim >> v0;
			   std::cout << " -- read: row dimension is " << _rowdim << " and column dimension is " <<_coldim << std::endl;
			   while (is >> r >> c >> v)
			   {
			   if ( r == 0 && c == 0 && v == 0 ) {std::cout << " -- read: reach the end" << std::endl;break;}
			   indexPairs.push_back(std::pair<Index,Index>(static_cast<Index>(r), static_cast<Index>(c)));
			   ++count;
			   }
			   */
			std::cout << " -- read: " << count << std::endl;

			//S.getRows(_rowdim); S.getColumns(_coldim);
			init(indexPairs);
			return is;
		}
		std::ostream& write(std::ostream& out =  std::cout) const
		{
			out << "ZeroOne Matrix: _index.size() " << _index.size();
			out << ", _indexP.size() " << _indexP.size();
			out << ", _rowdim " << _rowdim;
			out << ", _coldim " << _coldim;
			return out;
		}

		const Field& field() const
		{ return _field; }

		/* Non blackbox function.  Tells the number of nonzero entries
		*/
		size_t nnz() const
		{ return _index.size(); };


		typedef MatrixCategories::BlackboxTag MatrixCategory;

	protected:

		Field _field; // The field used by this class

		/* _indexP is a pointer to an array of row indexes.  _colP is a pointer
		 * to an array of column indexes. These two are the other arrays of a
		 * NAGSparse format Matrix.  _rowdim and _coldim are the number of rows and
		 * columns of the Matrix if it were in dense format.  _nnz is the Number of
		 * Non-Zero elements in the Matrix.  It also happens to be the length of
		 * the three NAGSparse arrays.
		 *
		 * Note: I changed their names since now how the matrix is sorted is
		 * decided by the member "sorted" of type howToSort and we no longer
		 * keep two copies of zo matrix by having (_col, _rowP) and (_row, _colP)
		 *
		 * _index stores the real row or column index, and _indexP always points to
		 * some position in _index which is the beginning or a row or a column, row
		 * or column depending on how the matrix is sorted
		 *
		 *
		 */
	public: //temporarily
		mutable IndexVector _index; // The nnz indices sorted by row or by col
		mutable PointerVector _indexP; // the pointers to beginning of each row if sorted by row
		// and to beginning of each col if sorted by col

		//IndexVector _col; // The nnz column indices
		//PointerVector _rowP; // the _rowdim+1 pointers to beginning of row in _col

		/* Keep another copy of the Matrix for applyTranspose */
		//IndexVector _row; // The nnz row indices
		//PointerVector _colP; // the _coldim+1 pointers to beginning of col in _row

		Index _rowdim, _coldim;
		mutable bool sorted;

	}; //ZeroOne


}//End of LinBox

#ifdef _RUNOPENMP
#include "zoi.inl"
#else
#include "zo.inl"
#endif

#endif // __LINBOX_zero_one_H


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