Compression storage of C + + sparse matrices

Sparse matrices

m*n The number of valid values in the matrix far less than number of invalid values and distribution no rules .

Eg:

int array [6][5] = {{1, 0, 3, 0, 5},

{0, 0, 0, 0, 0},

{0, 0, 0, 0, 0},

{2, 0, 4, 0, 6},

{0, 0, 0, 0, 0},

{0, 0, 0, 0, 0}};

Compressed storage of sparse matrices  

compressed storage values store a very small number of valid data. Use {row,col,value} //column value triples Store each valid data, ternary group according to the position of the original matrix,

Program code:

#include <vector>   //push pop operator[]  and sequential table consistent  template<class  t>struct triple  //defines a ternary group   can be accessed directly as defined as struct{size_t _row;size_t _col; T _value; triple (Size_t row, size_t col, const t& value): _row (Row) ,  _col (COL),  _value (value) {}};  template<class t>class sparsematrix{public : Sparsematrix (Const t* a, size_t m, size_t n,const t& invalid)// Const t& invalid indicates which is invalid data: _m (M),  _n (N),  invalid (invalid) {for  (size_t i  = 0; i < m; ++i) {for  (size_t j = 0; j < n; &NBSP;++J) {if  (a[i*n + j] != invalid)  //not equal to invalid value {triple<t> t (i, j, &NBSP;A[I*N&NBSP;+&NBSP;J]); _a.push_back (t);    }}}} void display () {Size_t index  = 0;for  (size_t i = 0; i < _m; ++i) {for  (size_t j = 0; &NBSP;J&NBSP;&LT;&NBSP;_N;&NBSP;++J) {if  (index<_a.size () &&i == _a[index]._row  && j == _a[index]._col) {cout << _a[index].value <<  "   "; ++index;} else{cout << _invalid <<  " ";}} Cout << endl;} Cout << endl;} protected:        //Storage Ternary Array//triple<t>* _a;         Direct use of dynamic sequential table vector<triple<t>> _a;size_t _m;size_t _n; t _invalid;};  void test2 () {int a[6][5] = { { 1, 0, 3, 0, 5 },                 { 0,  0, 0, 0, 0 },                { 0, 0, 0, 0, 0 },                 { 2, 0, 4, 0 , 6 },                 { 0, 0, 0, 0, 0 },                 { 0, 0, 0, 0, 0 } }; SPARSEMATRIX&LT;INT&GT;&NBSP;SM ((int*) a,6,5,0)  //cast to a one-dimensional array   array  6 row  5 column   illegal value 0SM. Display (); }  #include <iostream>using namespace std;  #include <stdlib.h># Include "Matrix.h"  int main () {//test1 (); Test2 (); System ("pause"); return 0;}

Operation Result:

1 0 3) 0 5

0 0 0) 0 0

0 0 0) 0 0

2 0 4) 0 6

0 0 0) 0 0

0 0 0) 0 0

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Compression storage of C + + sparse matrices