comparison dsp/segmentation/cluster_melt.c @ 18:8e90a56b4b5f

* merge in segmentation code from soundbite plugin/library repository

+/*
+ *  cluster.c
+ *  cluster_melt
+ *
+ *  Created by Mark Levy on 21/02/2006.
+ *  Copyright 2006 Centre for Digital Music, Queen Mary, University of London. All rights reserved.
+ *
+ */
+
+#include <stdlib.h>
+
+#include "cluster_melt.h"
+
+#define DEFAULT_LAMBDA 0.02;
+#define DEFAULT_LIMIT 20;
+
+double kldist(double* a, double* b, int n) {
+	/* NB assume that all a[i], b[i] are non-negative
+	because a, b represent probability distributions */
+	double q, d;
+	int i;
+	
+	d = 0;
+	for (i = 0; i < n; i++)
+	{
+		q = (a[i] + b[i]) / 2.0;
+		if (q > 0)
+		{
+			if (a[i] > 0)
+				d += a[i] * log(a[i] / q);
+			if (b[i] > 0)
+				d += b[i] * log(b[i] / q);
+		}
+	}
+	return d;		
+}	
+
+void cluster_melt(double *h, int m, int n, double *Bsched, int t, int k, int l, int *c) {
+	double lambda, sum, beta, logsumexp, maxlp;
+	int i, j, a, b, b0, b1, limit, B, it, maxiter, maxiter0, maxiter1;
+	double** cl;	/* reference histograms for each cluster */
+	int** nc;	/* neighbour counts for each histogram */
+	double** lp;	/* soft assignment probs for each histogram */
+	int* oldc;	/* previous hard assignments (to check convergence) */
+	
+	/* NB h is passed as a 1d row major array */
+	
+	/* parameter values */
+	lambda = DEFAULT_LAMBDA;
+	if (l > 0)
+		limit = l;
+	else
+		limit = DEFAULT_LIMIT;		/* use default if no valid neighbourhood limit supplied */
+	B = 2 * limit + 1;
+	maxiter0 = 20;	/* number of iterations at initial temperature */
+	maxiter1 = 5;	/* number of iterations at subsequent temperatures */
+	
+	/* allocate memory */	
+	cl = (double**) malloc(k*sizeof(double*));
+	for (i= 0; i < k; i++)
+		cl[i] = (double*) malloc(m*sizeof(double));
+	
+	nc = (int**) malloc(n*sizeof(int*));
+	for (i= 0; i < n; i++)
+		nc[i] = (int*) malloc(k*sizeof(int));
+	
+	lp = (double**) malloc(n*sizeof(double*));
+	for (i= 0; i < n; i++)
+		lp[i] = (double*) malloc(k*sizeof(double));
+	
+	oldc = (int*) malloc(n * sizeof(int));
+	
+	/* initialise */
+	for (i = 0; i < k; i++)
+	{
+		sum = 0;
+		for (j = 0; j < m; j++)
+		{
+			cl[i][j] = rand();	/* random initial reference histograms */
+			sum += cl[i][j] * cl[i][j];
+		}
+		sum = sqrt(sum);
+		for (j = 0; j < m; j++)
+		{
+			cl[i][j] /= sum;	/* normalise */
+		}
+	}	
+	//print_array(cl, k, m);
+	
+	for (i = 0; i < n; i++)
+		c[i] = 1;	/* initially assign all histograms to cluster 1 */
+	
+	for (a = 0; a < t; a++)
+	{
+		beta = Bsched[a];
+		
+		if (a == 0)
+			maxiter = maxiter0;
+		else
+			maxiter = maxiter1;
+		
+		for (it = 0; it < maxiter; it++)
+		{
+			//if (it == maxiter - 1)
+			//	mexPrintf("hasn't converged after %d iterations\n", maxiter);
+			
+			for (i = 0; i < n; i++)
+			{
+				/* save current hard assignments */
+				oldc[i] = c[i];
+				
+				/* calculate soft assignment logprobs for each cluster */
+				sum = 0;
+				for (j = 0; j < k; j++)
+				{
+					lp[i][ j] = -beta * kldist(cl[j], &h[i*m], m);
+					
+					/* update matching neighbour counts for this histogram, based on current hard assignments */
+					/* old version:
+					nc[i][j] = 0;	
+					if (i >= limit && i <= n - 1 - limit)
+					{
+							for (b = i - limit; b <= i + limit; b++)
+							{
+								if (c[b] == j+1)
+									nc[i][j]++;
+							}
+							nc[i][j] = B - nc[i][j];
+					}
+					*/
+					b0 = i - limit;
+					if (b0 < 0)
+						b0 = 0;
+					b1 = i + limit;
+					if (b1 >= n)
+						b1 = n - 1;
+					nc[i][j] = b1 - b0 + 1;		/* = B except at edges */
+					for (b = b0; b <= b1; b++)
+						if (c[b] == j+1)
+							nc[i][j]--;
+					
+					sum += exp(lp[i][j]);
+				}
+				
+				/* normalise responsibilities and add duration logprior */
+				logsumexp = log(sum);
+				for (j = 0; j < k; j++)
+					lp[i][j] -= logsumexp + lambda * nc[i][j];				
+			}
+			//print_array(lp, n, k);
+			/*
+			for (i = 0; i < n; i++)
+			{
+				 for (j = 0; j < k; j++)
+					 mexPrintf("%d ", nc[i][j]);
+				 mexPrintf("\n");
+			} 
+			*/
+			
+			
+			/* update the assignments now that we know the duration priors
+			based on the current assignments */
+			for (i = 0; i < n; i++)
+			{
+				maxlp = lp[i][0];
+				c[i] = 1;
+				for (j = 1; j < k; j++)
+					if (lp[i][j] > maxlp)
+					{
+						maxlp = lp[i][j];
+						c[i] = j+1;
+					}
+			}
+				
+			/* break if assignments haven't changed */
+			i = 0;
+			while (i < n && oldc[i] == c[i])
+				i++;
+			if (i == n)
+				break;
+			
+			/* update reference histograms now we know new responsibilities */
+			for (j = 0; j < k; j++)
+			{
+				for (b = 0; b < m; b++)
+				{
+					cl[j][b] = 0;
+					for (i = 0; i < n; i++)
+					{
+						cl[j][b] += exp(lp[i][j]) * h[i*m+b];
+					}	
+				}
+				
+				sum = 0;				
+				for (i = 0; i < n; i++)
+					sum += exp(lp[i][j]);
+				for (b = 0; b < m; b++)
+					cl[j][b] /= sum;	/* normalise */
+			}	
+			
+			//print_array(cl, k, m);
+			//mexPrintf("\n\n");
+		}
+	}
+		
+	/* free memory */
+	for (i = 0; i < k; i++)
+		free(cl[i]);
+	free(cl);
+	for (i = 0; i < n; i++)
+		free(nc[i]);
+	free(nc);
+	for (i = 0; i < n; i++)
+		free(lp[i]);
+	free(lp);
+	free(oldc);	
+}
+
+