# HG changeset patch
# User Chris Cannam
# Date 1587745496 -3600
# Node ID b2781519475229108766ed9868630ade4fe8257f
# Parent  d0d47127d8cc140d6c3753603174f97e2164f39f
Half-written rewrite of this part of SML code

diff -r d0d47127d8cc -r b27815194752 align/DTW.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/align/DTW.h	Fri Apr 24 17:24:56 2020 +0100
@@ -0,0 +1,90 @@
+/* -*- 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 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_DTW_H
+#define SV_DTW_H
+
+#include <vector>
+
+class DTW
+{
+public:
+    typedef double cost_t;
+
+    struct CostOption {
+        bool present;
+        cost_t cost;
+    };
+
+    enum class Direction {
+        None,
+        Up,
+        Down
+    };
+    
+    struct Value {
+        Direction direction;
+        cost_t cost;
+    };
+
+    static cost_t choose(CostOption x, CostOption y, CostOption d) {
+        if (x.present && y.present) {
+            if (!d.present) {
+                throw std::logic_error("if x & y both exist, so must diagonal");
+            }
+            return std::min(std::min(x.cost, y.cost), d.cost);
+        } else if (x.present) {
+            return x.cost;
+        } else if (y.present) {
+            return y.cost;
+        } else {
+            return 0.0;
+        }
+    }
+
+    static cost_t calculateCost(Value a, Value b) {
+        auto together = [](cost_t c1, cost_t c2) {
+                            auto diff = std::abs(c1 - c2);
+                            return (diff < 1.0 ? -1.0 :
+                                    diff > 3.0 ?  1.0 :
+                                    0.0);
+                        };
+        auto opposing = [](cost_t c1, cost_t c2) {
+                            auto diff = c1 + c2;
+                            return (diff < 2.0 ? 1.0 :
+                                    2.0);
+                        };
+        if (a.direction == Direction::None || b.direction == Direction::None) {
+            if (a.direction == b.direction) {
+                return 0.0;
+            } else {
+                return 1.0;
+            }
+        } else {
+            if (a.direction == b.direction) {
+                return together (a.cost, b.cost);
+            } else {
+                return opposing (a.cost, b.cost);
+            }
+        }
+    }
+
+    static std::vector<std::vector<cost_t>> costSeries(std::vector<Value> s1,
+                                                       std::vector<Value> s2) {
+        
+    }
+    
+};
+
+#endif