Boost :: multi_array上与维度无关的循环？

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如何解决Boost :: multi_array上与维度无关的循环？？

好的，根据注释中已经提到的Google小组讨论以及库本身的示例之一，这是一个可能的解决方案，它使您可以在单个循环中遍历多数组中的所有值 提供一个检索这些元素中的每个元素的索引的方式（以防其他情况（如我的情况）所需）。

#include <iostream>
#include <boost/multi_array.hpp>
#include <boost/array.hpp>

const unsigned short int DIM = 3;
typedef double tValue;
typedef boost::multi_array<tValue,DIM> tArray;
typedef tArray::index Tindex;
typedef boost::array<Tindex, DIM> TindexArray;

Tindex geTindex(const tArray& m, const tValue* requestedElement, const unsigned short int direction)
{
  int offset = requestedElement - m.origin();
  return(offset / m.StriDes()[direction] % m.shape()[direction] +  m.index_bases()[direction]); 
}

TindexArray geTindexArray( const tArray& m, const tValue* requestedElement )
{
  TindexArray _index;
  for ( unsigned int dir = 0; dir < DIM; dir++ )
  {
    _index[dir] = geTindex( m, requestedElement, dir );
  }

  return _index;
}


int main()
{ 
  double* exampleData = new double[24];
  for ( int i = 0; i < 24; i++ ) { exampleData[i] = i; }

  tArray A( boost::extents[2][3][4] );
  A.assign(exampleData,exampleData+24);

  tValue* p = A.data();
  TindexArray index;
  for ( int i = 0; i < A.num_elements(); i++ )
  {
    index = geTindexArray( A, p );
    std::cout << index[0] << " " << index[1] << " " << index[2] << " value = " << A(indeX) << "  check = " << *p << std::endl;
    ++p;
  }

  return 0;
}

输出应为

0 0 0 value = 0 check = 0
0 0 1 value = 1 check = 1
0 0 2 value = 2 check = 2
0 0 3 value = 3 check = 3
0 1 0 value = 4 check = 4
0 1 1 value = 5 check = 5
0 1 2 value = 6 check = 6
0 1 3 value = 7 check = 7
0 2 0 value = 8 check = 8
0 2 1 value = 9 check = 9
0 2 2 value = 10 check = 10
0 2 3 value = 11 check = 11
1 0 0 value = 12 check = 12
1 0 1 value = 13 check = 13
1 0 2 value = 14 check = 14
1 0 3 value = 15 check = 15
1 1 0 value = 16 check = 16
1 1 1 value = 17 check = 17
1 1 2 value = 18 check = 18
1 1 3 value = 19 check = 19
1 2 0 value = 20 check = 20
1 2 1 value = 21 check = 21
1 2 2 value = 22 check = 22
1 2 3 value = 23 check = 23

因此内存布局从外部索引到内部索引。请注意，该geTindex函数依赖于boost :: multi_array提供的默认内存布局。如果更改了阵列基础或存储顺序，则必须进行调整。

解决方法

typedef boost::multi_array<int,N> tDataArray;
boost::array<tDataArray::index,N> shape;
shape.fill(m);
tDataArray A(shapE);

  boost::array<tDataArray::index,2> index;
  for ( int i = 0; i < m; i++ )
  {
    for ( int j = 0; j < m; j++ )
    {
      index = {{ i,j }};
      cout << A ( index ) << endl;
    }
  }