diff base/MovingMedian.h @ 1573:f04038819c26 spectrogramparam

Introduce & make use of faster MovingMedian class (now with resize capability)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/base/MovingMedian.h	Thu Nov 08 15:02:30 2018 +0000
@@ -0,0 +1,235 @@
+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
+
+/*
+    Sonic Visualiser
+    An audio file viewer and annotation editor.
+    Centre for Digital Music, Queen Mary, University of London.
+    This file copyright 2007-2015 Particular Programs Ltd, 
+    copyright 2018 Queen Mary University of London.
+    
+    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 2 of the
+    License, or (at your option) any later version.  See the file
+    COPYING included with this distribution for more information.
+*/
+
+#ifndef SV_MOVING_MEDIAN_H
+#define SV_MOVING_MEDIAN_H
+
+#include <bqvec/Allocators.h>
+#include <bqvec/VectorOps.h>
+
+#include <algorithm>
+#include <iostream>
+#include <stdexcept>
+
+/**
+ * Obtain the median (or other percentile) of a moving window across a
+ * time series. Construct the MovingMedian object, then push() each
+ * new value in the time series and get() the median of the most
+ * recent window. The size of the window, and the percentile
+ * calculated, can both be changed after construction.
+ *
+ * Note that for even-sized windows, the "median" is taken to be the
+ * value at the start of the second half when sorted, e.g. for size 4,
+ * the element at index 2 (zero-based) in the sorted window.
+ *
+ * Not thread-safe.
+ */
+template <typename T>
+class MovingMedian
+{
+public:
+    MovingMedian(int size, double percentile = 50.f) :
+        m_size(size),
+        m_percentile(percentile) {
+        if (size < 1) throw std::logic_error("size must be >= 1");
+        m_frame = breakfastquay::allocate_and_zero<T>(size);
+	m_sorted = breakfastquay::allocate_and_zero<T>(size);
+        calculateIndex();
+    }
+
+    ~MovingMedian() { 
+        breakfastquay::deallocate(m_frame);
+        breakfastquay::deallocate(m_sorted);
+    }
+
+    MovingMedian(const MovingMedian &) =delete;
+    MovingMedian &operator=(const MovingMedian &) =delete;
+
+    void setPercentile(double p) {
+        m_percentile = p;
+        calculateIndex();
+    }
+
+    void push(T value) {
+        if (value != value) {
+            std::cerr << "WARNING: MovingMedian: NaN encountered" << std::endl;
+            value = T();
+        }
+	drop(m_frame[0]);
+        breakfastquay::v_move(m_frame, m_frame+1, m_size-1);
+	m_frame[m_size-1] = value;
+	put(value);
+    }
+
+    T get() const {
+	return m_sorted[m_index];
+    }
+
+    int size() const {
+        return m_size;
+    }
+
+    void reset() {
+        breakfastquay::v_zero(m_frame, m_size);
+        breakfastquay::v_zero(m_sorted, m_size);
+    }
+
+    void resize(int target) {
+        if (target == m_size) return;
+        int diff = std::abs(target - m_size);
+        if (target > m_size) { // grow
+            // we don't want to change the median, so fill spaces with it
+            T fillValue = get();
+            m_frame = breakfastquay::reallocate(m_frame, m_size, target);
+            breakfastquay::v_move(m_frame + diff, m_frame, m_size);
+            breakfastquay::v_set(m_frame, fillValue, diff);
+            m_sorted = breakfastquay::reallocate(m_sorted, m_size, target);
+            for (int sz = m_size + 1; sz <= target; ++sz) {
+                put(m_sorted, sz, fillValue);
+            }
+        } else { // shrink
+            for (int i = 0; i < diff; ++i) {
+                drop(m_sorted, m_size - i, m_frame[i]);
+            }
+            m_sorted = breakfastquay::reallocate(m_sorted, m_size, target);
+            breakfastquay::v_move(m_frame, m_frame + diff, target);
+            m_frame = breakfastquay::reallocate(m_frame, m_size, target);
+        }
+
+        m_size = target;
+        calculateIndex();
+    }
+
+    void checkIntegrity() const {
+        check();
+    }
+
+private:
+    int m_size;
+    double m_percentile;
+    int m_index;
+    T *m_frame;
+    T *m_sorted;
+
+    void calculateIndex() {
+        m_index = int((m_size * m_percentile) / 100.f);
+        if (m_index >= m_size) m_index = m_size-1;
+        if (m_index < 0) m_index = 0;
+    }
+    
+    void put(T value) {
+        put(m_sorted, m_size, value);
+    }
+
+    static void put(T *const sorted, int size, T value) {
+
+        // precondition: sorted points to size-1 sorted values,
+        // followed by an unused slot (i.e. only the first size-1
+        // values of sorted are actually sorted)
+        // 
+        // postcondition: sorted points to size sorted values
+        
+	T *ptr = std::lower_bound(sorted, sorted + size - 1, value);
+        breakfastquay::v_move(ptr + 1, ptr, int(sorted + size - ptr) - 1);
+	*ptr = value;
+    }
+
+    void drop(T value) {
+        drop(m_sorted, m_size, value);
+    }
+
+    static void drop(T *const sorted, int size, T value) {
+
+        // precondition: sorted points to size sorted values, one of
+        // which is value
+        //
+        // postcondition: sorted points to size-1 sorted values,
+        // followed by a slot that has been reset to default value
+        // (i.e. only the first size-1 values of sorted are actually
+        // sorted)
+
+	T *ptr = std::lower_bound(sorted, sorted + size, value);
+	if (*ptr != value) {
+            throw std::logic_error
+                ("MovingMedian::drop: value being dropped is not in array");
+        }
+        breakfastquay::v_move(ptr, ptr + 1, int(sorted + size - ptr) - 1);
+        sorted[size-1] = T();
+    }
+
+    void check() const {
+        bool good = true;
+        for (int i = 1; i < m_size; ++i) {
+            if (m_sorted[i] < m_sorted[i-1]) {
+                std::cerr << "ERROR: MovingMedian::checkIntegrity: "
+                          << "mis-ordered elements in sorted array starting "
+                          << "at index " << i << std::endl;
+                good = false;
+                break;
+            }
+        }
+        for (int i = 0; i < m_size; ++i) {
+            bool found = false;
+            for (int j = 0; j < m_size; ++j) {
+                if (m_sorted[j] == m_frame[i]) {
+                    found = true;
+                    break;
+                }
+            }
+            if (!found) {
+                std::cerr << "ERROR: MovingMedian::checkIntegrity: "
+                          << "element in frame at index " << i
+                          << " not found in sorted array" << std::endl;
+                good = false;
+                break;
+            }
+        }
+        for (int i = 0; i < m_size; ++i) {
+            bool found = false;
+            for (int j = 0; j < m_size; ++j) {
+                if (m_sorted[i] == m_frame[j]) {
+                    found = true;
+                    break;
+                }
+            }
+            if (!found) {
+                std::cerr << "ERROR: MovingMedian::checkIntegrity: "
+                          << "element in sorted array at index " << i
+                          << " not found in source frame" << std::endl;
+                good = false;
+                break;
+            }
+        }
+        if (!good) {
+            std::cerr << "Frame contains:" << std::endl;
+            std::cerr << "[ ";
+            for (int j = 0; j < m_size; ++j) {
+                std::cerr << m_frame[j] << " ";
+            }
+            std::cerr << "]" << std::endl;
+            std::cerr << "Sorted array contains:" << std::endl;
+            std::cerr << "[ ";
+            for (int j = 0; j < m_size; ++j) {
+                std::cerr << m_sorted[j] << " ";
+            }
+            std::cerr << "]" << std::endl;
+            throw std::logic_error("MovingMedian failed integrity check");
+        }
+    }
+};
+
+#endif
+