[ VIGRA Homepage | Class Index | Function Index | File Index | Main Page ]

details MultiArrayNavigator Class Template Reference VIGRA

A navigator that provides acces to the 1D subranges of an n-dimensional range given by a vigra::MultiIterator and an nD shape. More...

#include "vigra/navigator.hxx"


Public Types

typedef MULTI_ITERATOR::multi_difference_type shape_type
typedef MULTI_ITERATOR::iterator iterator

Public Methods

 MultiArrayNavigator (MULTI_ITERATOR const &i, shape_type const &shape, unsigned int inner_dimension)
void operator++ ()
void operator++ (int)
bool hasMore () const
bool atEnd () const


Detailed Description


template<class MULTI_ITERATOR, unsigned int N>
class vigra::MultiArrayNavigator< MULTI_ITERATOR, N >

A navigator that provides acces to the 1D subranges of an n-dimensional range given by a vigra::MultiIterator and an nD shape.

Normally, the innermost loop of an iteration extends over the innermost dimension of a given array. Sometimes, however, it is necessary to have some other dimension in the inner loop. For example, instead of iterating over the rows, the inner loop should extend over the columns. The class MultiArrayNavigator encapsulates the necessary functionality. Given an arbitrary dimensional array (represented by a vigra::MultiIterator/shape pair), and the desired inner loop dimension d, it moves the encapsulated iterator to all possible starting points of 1D subsets along the given dimension (e.g. all columns). By calling begin() and end(), one can then obtain an STL-compatible 1-dimensional iterator for the current subset.

The template parameters specify the embedded iterator type and its dimension.

Usage:

#include "vigra/navigator.hxx"

Namespace: vigra

    typedef vigra::MultiArray<3, int>  Array;

    Array a(Array::size_type(X, Y, Z));

    typedef vigra::MultiArrayNavigator<Array::traverser, 3> Navigator;

    for(int d=0; d<3; ++d)
    {
        // create Navigator for dimension d
        Navigator nav(a.traverser_begin(), a.shape(), d);

        // outer loop: move navigator to all starting points
        // of 1D subsets that run parallel to coordinate axis d
        for(; nav.hasMore(); ++nav)
        {
            // inner loop: linear iteration over current subset
            //             d == {0, 1, 2}: interate along {x, y, z}-axis respectively
             Navigator::iterator i = nav.begin(), end = nav.end();
            for(; i != end; ++i)
                // do something
        }
    }


Member Typedef Documentation


typedef MULTI_ITERATOR::iterator iterator

 

The iterator type for the inner loop (result of begin() and end()).


typedef MULTI_ITERATOR::multi_difference_type shape_type

 

The required shape type for the given iterator type.


Constructor & Destructor Documentation


MultiArrayNavigator MULTI_ITERATOR const &    i,
shape_type const &    shape,
unsigned int    inner_dimension
[inline]

 

Construct navigator for multi-dimensional iterator i, array shape shape and inner loop dimension inner_dimension.


Member Function Documentation


bool atEnd   const [inline]

 

true if iterator is exhausted.


bool hasMore   const [inline]

 

true if there are more elements.


void operator++ int    [inline]

 

Advance to next starting location.


void operator++   [inline]

 

Advance to next starting location.


The documentation for this class was generated from the following file:

© Ullrich Köthe (koethe@informatik.uni-hamburg.de)
Cognitive Systems Group, University of Hamburg, Germany

html generated using doxygen and Python
VIGRA 1.3.2 (27 Jan 2005)