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116 lines
2.8 KiB
116 lines
2.8 KiB
#include <vector>
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#include <iostream>
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#include <iterator>
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#include <numeric>
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#include <cassert>
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#include <cmath>
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#include <boost/assign.hpp>
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#include "striding_iterator.hpp"
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#include "periodic_iterator.hpp"
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#include "wavelet.hpp"
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bool is_pow_of_two(int n){
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return (n & (n - 1)) == 0;
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}
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template <typename Iterator>
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void shuffle(Iterator begin, Iterator end){
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typedef typename std::iterator_traits<Iterator>::value_type value_type;
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typedef typename std::iterator_traits<Iterator>::difference_type diff_type;
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diff_type s = end - begin;
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assert(s % 2 == 0);
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std::vector<value_type> v(s);
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std::copy(strided(begin , 2), strided(end , 2), v.begin());
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std::copy(strided(begin+1, 2), strided(end+1, 2), v.begin() + s/2);
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std::copy(v.begin(), v.end(), begin);
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}
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template <typename Iterator>
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void unshuffle(Iterator begin, Iterator end){
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typedef typename std::iterator_traits<Iterator>::value_type value_type;
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typedef typename std::iterator_traits<Iterator>::difference_type diff_type;
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diff_type s = end - begin;
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assert(s % 2 == 0);
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std::vector<value_type> v(s);
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std::copy(begin, begin + s/2, strided(v.begin(), 2));
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std::copy(begin + s/2, end, strided(v.begin()+1, 2));
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std::copy(v.begin(), v.end(), begin);
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}
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template <typename Iterator>
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void wavelet(Iterator begin, Iterator end){
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int s = end - begin;
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for(int i = s; i >= 4; i >>= 1){
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// half interval
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end = begin + i;
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assert(is_pow_of_two(end - begin));
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// multiply with Wn
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wavelet_mul(begin, end);
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// then with Sn
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shuffle(begin, end);
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}
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}
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template <typename Iterator>
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void unwavelet(Iterator begin, Iterator end){
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int s = end - begin;
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for(int i = 4; i <= s; i <<= 1){
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// double interval
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end = begin + i;
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assert(is_pow_of_two(end - begin));
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// unshuffle: Sn^-1
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unshuffle(begin, end);
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// then Wn^-1
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wavelet_inv(begin, end);
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}
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}
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struct filter{
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filter(double threshold)
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: threshold(threshold)
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{}
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void operator()(double& x){
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if(std::abs(x) <= threshold) x = 0;
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}
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double threshold;
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};
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int main(){
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using namespace boost::assign;
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std::vector<double> input;
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input += 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;
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// print input
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std::copy(input.begin(), input.end(), std::ostream_iterator<double>(std::cout, "\n"));
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std::cout << std::endl;
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std::vector<double> thresholds;
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thresholds += 0.0, 0.1, 0.2, 0.5;
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for(int i = 0; i < thresholds.size(); ++i){
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std::vector<double> v;
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v = input;
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// transform to wavelet domain
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wavelet(v.begin(), v.end());
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// apply threshold
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std::for_each(v.begin(), v.end(), filter(thresholds[i]));
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int zeros = std::count(v.begin(), v.end(), 0.0);
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// transform back to sample domain
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unwavelet(v.begin(), v.end());
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// print compressed
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std::cout << "\ncp: " << zeros / double(v.size()) << std::endl;
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std::copy(v.begin(), v.end(), std::ostream_iterator<double>(std::cout, "\n"));
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std::cout << std::endl;
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}
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}
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