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/* Copyright (c) 2008-2022 the MRtrix3 contributors.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* Covered Software is provided under this License on an "as is"
* basis, without warranty of any kind, either expressed, implied, or
* statutory, including, without limitation, warranties that the
* Covered Software is free of defects, merchantable, fit for a
* particular purpose or non-infringing.
* See the Mozilla Public License v. 2.0 for more details.
*
* For more details, see http://www.mrtrix.org/.
*/
#ifndef __algo_random_loop_h__
#define __algo_random_loop_h__
#include "apply.h"
#include "progressbar.h"
#include "stride.h"
#include "image_helpers.h"
#include <unordered_set>
#include <algorithm> // std::shuffle
#include <iterator>
namespace MR
{
template <class ImageType, class RandomEngine>
class Random_loop { NOMEMALIGN
public:
Random_loop (ImageType& in,
RandomEngine& random_engine,
const size_t& axis = 0,
const size_t& number_iterations = std::numeric_limits<ssize_t>::max()):
image (in),
engine (random_engine),
ax (axis),
idx(image.size(axis)),
max_cnt (number_iterations),
status (true),
cnt (0)
{
init();
set_next_index();
}
void init() {
std::iota (std::begin(idx), std::end(idx), 0);
std::shuffle(std::begin(idx), std::end(idx), engine);
cnt = 0;
it = std::begin(idx);
stop = std::end(idx);
}
void set_next_index() {
++cnt;
image.index(ax) = *it;
it++;
}
void operator++ ()
{
set_next_index();
if (cnt > max_cnt or it == stop) {
status = false;
}
}
operator bool() const
{
return status && image.index(ax) >= 0 && image.index(ax) < image.size(ax);
}
private:
ImageType& image;
RandomEngine& engine;
size_t ax;
vector<size_t> idx;
vector<size_t>::iterator it;
vector<size_t>::iterator stop;
size_t max_cnt;
bool status;
size_t cnt;
};
// Random_sparse_loop: ok for VERY sparse loops, slows down significantly at higher density (>5%)
template <class ImageType>
class Random_sparse_loop { NOMEMALIGN
public:
Random_sparse_loop (ImageType& in,
const size_t& axis = 0,
const size_t& number_iterations = std::numeric_limits<ssize_t>::max(),
const bool repeat = false,
const ssize_t& min_index = 0,
const ssize_t& max_index = std::numeric_limits<ssize_t>::max()):
image (in),
repeat_ (repeat),
status (true),
ax (axis),
cnt (0),
min_idx (min_index)
{
if (max_index < image.size(ax))
range = max_index - min_idx + 1;
else
range = image.size(ax) - min_idx;
if (number_iterations < range)
max_cnt = number_iterations;
else
max_cnt = range;
assert (range >= 1);
assert (max_cnt >= 1);
if (repeat_)
set_next_index_with_repeat();
else
set_next_index_no_repeat();
}
void set_next_index_no_repeat() {
while (cnt < max_cnt){
index = rand() % range + min_idx;
if (!idx_done.count(index)){
idx_done.insert(index);
break;
}
}
++cnt;
image.index(ax) = index;
assert(idx_done.size() < range);
}
void set_next_index_with_repeat() {
index = rand() % range + min_idx;
++cnt;
image.index(ax) = index;
}
void operator++ ()
{
if (repeat_)
set_next_index_with_repeat();
else
set_next_index_no_repeat();
if (cnt > max_cnt) {
status = false;
}
}
operator bool() const
{
return status && image.index(ax) >= 0 && image.index(ax) < image.size(ax);
}
private:
ImageType& image;
bool repeat_;
bool status;
size_t ax;
size_t cnt;
ssize_t min_idx;
size_t range;
size_t max_cnt;
ssize_t index;
std::unordered_set<ssize_t> idx_done;
};
template <class ImageType, class IterType>
class Iterator_loop { NOMEMALIGN
public:
Iterator_loop (ImageType& in,
IterType first,
IterType last,
const size_t& axis = 0,
const size_t& number_iterations = std::numeric_limits<ssize_t>::max()):
image (in),
ax (axis),
start (first),
stop (last),
max_cnt (number_iterations),
status (true),
cnt (0)
{
set_next_index();
}
void set_next_index() {
++cnt;
image.index(ax) = *start;
start++;
}
void operator++ ()
{
set_next_index();
if (cnt > max_cnt or start == stop) {
status = false;
}
}
operator bool() const
{
return status && image.index(ax) >= 0 && image.index(ax) < image.size(ax);
}
private:
ImageType& image;
size_t ax;
IterType& start;
IterType& stop;
size_t max_cnt;
bool status;
size_t cnt;
};
//! @}
}
#endif
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