moving_median_filter.hpp

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/*
 * eDSP, A cross-platform Digital Signal Processing library written in modern C++.
 * Copyright (C) 2018 Mohammed Boujemaoui Boulaghmoudi, All rights reserved.
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation, either version 3 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of  MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along width
 * this program.  If not, see <http://www.gnu.org/licenses/>
 *
 * File: moving_median_filter.hpp
 * Author: Mohammed Boujemaoui
 * Date: 14/6/2018
 */
#ifndef EDSP_FILTER_MOVING_MEDIAN_FILTER_H
#define EDSP_FILTER_MOVING_MEDIAN_FILTER_H

#include <edsp/types/ring_buffer.hpp>
#include <edsp/statistics/median.hpp>

namespace edsp { namespace filter {

    template <typename T, typename Allocator = std::allocator<T>>
    class moving_median {
    public:
        using size_type  = std::size_t;
        using value_type = T;

        explicit moving_median(size_type N);

        size_type size() const;

        void resize(size_type N);

        void reset();

        template <typename InputIt, typename OutputIt>
        void filter(InputIt first, InputIt last, OutputIt d_first);

    private:
        edsp::ring_buffer<T, Allocator> window_;
        T accumulated_{0};
    };

    template <typename T, typename Allocator>
    moving_median<T, Allocator>::moving_median(size_type N) : window_(N, T()) {}

    template <typename T, typename Allocator>
    typename moving_median<T, Allocator>::size_type moving_median<T, Allocator>::size() const {
        return window_.capacity();
    }

    template <typename T, typename Allocator>
    void moving_median<T, Allocator>::reset() {
        window_.clear();
    }

    template <typename T, typename Allocator>
    template <typename InputIt, typename OutputIt>
    void moving_median<T, Allocator>::filter(InputIt first, InputIt last, OutputIt d_first) {
        for (; first != last; ++d_first, ++first) {
            window_.push_back(*first);
            *d_first = statistics::median(window_.cbegin(), window_.cend());
        }
    }

    template <typename T, typename Allocator>
    void moving_median<T, Allocator>::resize(size_type N) {
        window_.resize(N);
    }

}} // namespace edsp::filter

#endif // EDSP_FILTER_MOVING_MEDIAN_FILTER_H