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cv::NAryMatIterator Class Reference

#include <core.hpp>

Public Member Functions

void init (const Mat **arrays, Mat *planes, int narrays=-1)
 the separate iterator initialization method
 
 NAryMatIterator ()
 the default constructor
 
 NAryMatIterator (const Mat **arrays, Mat *planes, int narrays=-1)
 the full constructor taking arbitrary number of n-dim matrices
 
NAryMatIteratoroperator++ ()
 proceeds to the next plane of every iterated matrix
 
NAryMatIterator operator++ (int)
 proceeds to the next plane of every iterated matrix (postfix increment operator)
 

Public Attributes

const Mat ** arrays
 the iterated arrays
 
int narrays
 the number of arrays
 
int nplanes
 the number of planes in each array
 
Matplanes
 the current planes
 

Protected Attributes

int idx
 
int iterdepth
 

Detailed Description

n-Dimensional Dense Matrix Iterator Class.

The class cv::NAryMatIterator is used for iterating over one or more n-dimensional dense arrays (cv::Mat's).

The iterator is completely different from cv::Mat_ and cv::SparseMat_ iterators. It iterates through the slices (or planes), not the elements, where "slice" is a continuous part of the arrays.

Here is the example on how the iterator can be used to normalize 3D histogram:

void normalizeColorHist(Mat& hist)
{
#if 1
// intialize iterator (the style is different from STL).
// after initialization the iterator will contain
// the number of slices or planes
// the iterator will go through
Mat* arrays[] = { &hist, 0 };
Mat planes[1];
NAryMatIterator it(arrays, planes);
double s = 0;
// iterate through the matrix. on each iteration
// it.planes[i] (of type Mat) will be set to the current plane of
// i-th n-dim matrix passed to the iterator constructor.
for(int p = 0; p < it.nplanes; p++, ++it)
s += sum(it.planes[0])[0];
it = NAryMatIterator(hist);
s = 1./s;
for(int p = 0; p < it.nplanes; p++, ++it)
it.planes[0] *= s;
#elif 1
// this is a shorter implementation of the above
// using built-in operations on Mat
double s = sum(hist)[0];
hist.convertTo(hist, hist.type(), 1./s, 0);
#else
// and this is even shorter one
// (assuming that the histogram elements are non-negative)
normalize(hist, hist, 1, 0, NORM_L1);
#endif
}

You can iterate through several matrices simultaneously as long as they have the same geometry (dimensionality and all the dimension sizes are the same), which is useful for binary and n-ary operations on such matrices. Just pass those matrices to cv::MatNDIterator. Then, during the iteration it.planes[0], it.planes[1], ... will be the slices of the corresponding matrices

Constructor & Destructor Documentation

cv::NAryMatIterator::NAryMatIterator ( )

the default constructor

cv::NAryMatIterator::NAryMatIterator ( const Mat **  arrays,
Mat planes,
int  narrays = -1 
)

the full constructor taking arbitrary number of n-dim matrices

Member Function Documentation

void cv::NAryMatIterator::init ( const Mat **  arrays,
Mat planes,
int  narrays = -1 
)

the separate iterator initialization method

NAryMatIterator& cv::NAryMatIterator::operator++ ( )

proceeds to the next plane of every iterated matrix

NAryMatIterator cv::NAryMatIterator::operator++ ( int  )

proceeds to the next plane of every iterated matrix (postfix increment operator)

Member Data Documentation

const Mat** cv::NAryMatIterator::arrays

the iterated arrays

int cv::NAryMatIterator::idx
protected
int cv::NAryMatIterator::iterdepth
protected
int cv::NAryMatIterator::narrays

the number of arrays

int cv::NAryMatIterator::nplanes

the number of planes in each array

Mat* cv::NAryMatIterator::planes

the current planes


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