annotate base/LogRange.cpp @ 1343:c380e56c95f5 3.0-integration

Untabify some more
author Chris Cannam
date Fri, 06 Jan 2017 09:50:13 +0000
parents d4212687520e
children b061b9f8fca5
rev   line source
Chris@224 1 /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
Chris@224 2
Chris@224 3 /*
Chris@224 4 Sonic Visualiser
Chris@224 5 An audio file viewer and annotation editor.
Chris@224 6 Centre for Digital Music, Queen Mary, University of London.
Chris@224 7 This file copyright 2006 Chris Cannam.
Chris@224 8
Chris@224 9 This program is free software; you can redistribute it and/or
Chris@224 10 modify it under the terms of the GNU General Public License as
Chris@224 11 published by the Free Software Foundation; either version 2 of the
Chris@224 12 License, or (at your option) any later version. See the file
Chris@224 13 COPYING included with this distribution for more information.
Chris@224 14 */
Chris@224 15
Chris@224 16 #include "LogRange.h"
Chris@573 17 #include "system/System.h"
Chris@224 18
Chris@224 19 #include <algorithm>
Chris@464 20 #include <iostream>
Chris@224 21 #include <cmath>
Chris@224 22
Chris@224 23 void
Chris@1044 24 LogRange::mapRange(double &min, double &max, double logthresh)
Chris@224 25 {
Chris@224 26 if (min > max) std::swap(min, max);
Chris@224 27 if (max == min) max = min + 1;
Chris@224 28
Chris@1073 29 // cerr << "LogRange::mapRange: min = " << min << ", max = " << max << endl;
Chris@1073 30
Chris@224 31 if (min >= 0.f) {
Chris@224 32
Chris@1044 33 max = log10(max); // we know max != 0
Chris@224 34
Chris@224 35 if (min == 0.f) min = std::min(logthresh, max);
Chris@1044 36 else min = log10(min);
Chris@224 37
Chris@1073 38 // cerr << "LogRange::mapRange: positive: min = " << min << ", max = " << max << endl;
Chris@464 39
Chris@224 40 } else if (max <= 0.f) {
Chris@224 41
Chris@1044 42 min = log10(-min); // we know min != 0
Chris@224 43
Chris@224 44 if (max == 0.f) max = std::min(logthresh, min);
Chris@1044 45 else max = log10(-max);
Chris@224 46
Chris@224 47 std::swap(min, max);
Chris@224 48
Chris@1073 49 // cerr << "LogRange::mapRange: negative: min = " << min << ", max = " << max << endl;
Chris@464 50
Chris@224 51 } else {
Chris@224 52
Chris@224 53 // min < 0 and max > 0
Chris@224 54
Chris@1044 55 max = log10(std::max(max, -min));
Chris@224 56 min = std::min(logthresh, max);
Chris@464 57
Chris@1073 58 // cerr << "LogRange::mapRange: spanning: min = " << min << ", max = " << max << endl;
Chris@224 59 }
Chris@224 60
Chris@224 61 if (min == max) min = max - 1;
Chris@224 62 }
Chris@224 63
Chris@1044 64 double
Chris@1044 65 LogRange::map(double value, double thresh)
Chris@224 66 {
Chris@224 67 if (value == 0.f) return thresh;
Chris@1044 68 return log10(fabs(value));
Chris@224 69 }
Chris@224 70
Chris@1044 71 double
Chris@1044 72 LogRange::unmap(double value)
Chris@266 73 {
Chris@1044 74 return pow(10.0, value);
Chris@266 75 }
Chris@478 76
Chris@1038 77 static double
Chris@1044 78 sd(const std::vector<double> &values, int start, int n)
Chris@478 79 {
Chris@1038 80 double sum = 0.f, mean = 0.f, variance = 0.f;
Chris@1038 81 for (int i = 0; i < n; ++i) {
Chris@478 82 sum += values[start + i];
Chris@478 83 }
Chris@478 84 mean = sum / n;
Chris@1038 85 for (int i = 0; i < n; ++i) {
Chris@1038 86 double diff = values[start + i] - mean;
Chris@478 87 variance += diff * diff;
Chris@478 88 }
Chris@478 89 variance = variance / n;
Chris@1038 90 return sqrt(variance);
Chris@478 91 }
Chris@478 92
Chris@478 93 bool
Chris@1044 94 LogRange::useLogScale(std::vector<double> values)
Chris@478 95 {
Chris@478 96 // Principle: Partition the data into two sets around the median;
Chris@478 97 // calculate the standard deviation of each set; if the two SDs
Chris@478 98 // are very different, it's likely that a log scale would be good.
Chris@478 99
Chris@1038 100 int n = int(values.size());
Chris@1038 101 if (n < 4) return false;
Chris@478 102 std::sort(values.begin(), values.end());
Chris@1038 103 int mi = n / 2;
Chris@478 104
Chris@1038 105 double sd0 = sd(values, 0, mi);
Chris@1038 106 double sd1 = sd(values, mi, n - mi);
Chris@478 107
Chris@690 108 SVDEBUG << "LogRange::useLogScale: sd0 = "
Chris@687 109 << sd0 << ", sd1 = " << sd1 << endl;
Chris@478 110
Chris@478 111 if (sd0 == 0 || sd1 == 0) return false;
Chris@478 112
Chris@478 113 // I wonder what method of determining "one sd much bigger than
Chris@478 114 // the other" would be appropriate here...
Chris@1038 115 if (std::max(sd0, sd1) / std::min(sd0, sd1) > 10.) return true;
Chris@478 116 else return false;
Chris@478 117 }
Chris@478 118