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indexing.hpp
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indexing.hpp
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/**
* @file indexing.hpp
* @brief Indexing functions
* @author seonho.oh@gmail.com
* @date 2013-07-01
* @version 1.0
*
* @section LICENSE
*
* Copyright (c) 2013-2015, Seonho Oh
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the <ORGANIZATION> nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <cassert>
namespace arma_ext
{
using namespace arma;
//! @addtogroup ind
//! @{
/**
* @brief Convert subscripts to linear indices.
* @param rows the row size of matrix
* @param cols the column size of matrix
* @param r the row subscript
* @param c the column subscript
* @return the linear index equivalent to the row and column subscript @c r and @c c for a matrix of size @c rows and @c cols.
* @note Currently, only support 2D input.
*/
inline size_type sub2ind(size_type rows, size_type cols, size_type r, size_type c)
{
assert(r < rows && c < cols);
return r + rows * c;
}
//! Overloaded sub2ind for vectors
template <typename vec_type>
inline vec_type sub2ind(size_type rows, size_type cols, vec_type r, vec_type c, const typename arma_Mat_Col_Row_only<vec_type>::result* junk = 0)
{
//assert(r < rows && c < cols);
return r + rows * c;
}
//! template function specialization for double type
inline size_type sub2ind(double rows, double cols, double r, double c)
{
return sub2ind((size_type)arma_ext::round(rows), (size_type)arma_ext::round(cols), (size_type)arma_ext::round(r), (size_type)arma_ext::round(c));
}
/**
* @brief Subscripts from linear index
* @param rows the row size of matrix
* @param cols the column size of matrix
* @param ind A linear index.
* @return The subscripts correspond to the given linear index
*/
inline urowvec2 ind2sub(size_type rows, size_type cols, size_type ind)
{
urowvec2 out;
out[0] = ind % rows; out[1] = ind / rows;
return out;
}
inline arma::umat ind2sub(const arma::SizeMat& siz, const arma::uvec& ndx)
{
arma::umat out(ndx.size(), 2);
out.col(0) = ndx / siz.n_rows;
out.col(1) = mod(ndx, siz.n_rows);
return out;
}
/**
* @brief An implementation of MATLAB's colon operator start:interval:end.
* Create a vector contains [start, start + interval, ..., start + m * interval], where m = floor((end - start) / interval).
* @param start the first value
* @param interval interval
* @param end the last value
* @param junk reserved
* @return A vector that contains the sequence.
*/
template <typename vec_type>
vec_type colon(const typename vec_type::pod_type start,
const typename vec_type::pod_type interval,
const typename vec_type::pod_type end,
const typename arma_Mat_Col_Row_only<vec_type>::result* junk = 0)
{
typedef typename vec_type::elem_type eT;
typedef typename vec_type::pod_type T;
vec_type x;
if (((double)end - start) / interval < 0) return x;
x.set_size(uword(std::floor((end - start) / (double)interval)) + 1);
eT* x_mem = x.memptr();
for (uword i = 0 ; i < x.n_elem ; i++)
x_mem[i] = eT(start + i * interval);
return x;
}
/**
* @brief Overloaded function for sequence with interval as 1.<br>
* It is the same as start:end.
* @param start the first value
* @param end the last value
* @param junk reserved
*/
template <typename vec_type>
inline vec_type colon(const typename vec_type::pod_type start,
const typename vec_type::pod_type end,
const typename arma_Mat_Col_Row_only<vec_type>::result* junk = 0)
{
return colon<vec_type>(start, typename vec_type::pod_type(1), end);
}
//! @}
}