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Added Davies-Bouldin index [skip ci]

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This commit is contained in:
Andrew Kane
2022-02-15 19:08:47 -08:00
parent f5458414b8
commit 4ca264ba02
2 changed files with 45 additions and 0 deletions
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43
src/ivfbuild.c
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@@ -167,6 +167,8 @@ BuildCallback(Relation index, CALLBACK_ITEM_POINTER, Datum *values,
#ifdef IVFFLAT_KMEANS_DEBUG
buildstate->inertia += minDistance;
buildstate->listSums[closestCenter] += minDistance;
buildstate->listCounts[closestCenter]++;
#endif
/* Create a virtual tuple */
@@ -345,6 +347,8 @@ InitBuildState(IvfflatBuildState * buildstate, Relation heap, Relation index, In
#ifdef IVFFLAT_KMEANS_DEBUG
buildstate->inertia = 0;
buildstate->listSums = palloc0(sizeof(double) * buildstate->lists);
buildstate->listCounts = palloc0(sizeof(int) * buildstate->lists);
#endif
}
@@ -357,6 +361,11 @@ FreeBuildState(IvfflatBuildState * buildstate)
pfree(buildstate->centers);
pfree(buildstate->listInfo);
pfree(buildstate->normvec);
#ifdef IVFFLAT_KMEANS_DEBUG
pfree(buildstate->listSums);
pfree(buildstate->listCounts);
#endif
}
/*
@@ -503,6 +512,40 @@ CreateEntryPages(IvfflatBuildState * buildstate, ForkNumber forkNum)
#ifdef IVFFLAT_KMEANS_DEBUG
elog(INFO, "inertia: %.3e", buildstate->inertia);
/* Calculate Davies-Bouldin index */
if (buildstate->lists > 1)
{
double db = 0.0;
/* Calculate average distance */
for (int i = 0; i < buildstate->lists; i++)
{
if (buildstate->listCounts[i] > 0)
buildstate->listSums[i] /= buildstate->listCounts[i];
}
for (int i = 0; i < buildstate->lists; i++)
{
double max = 0.0;
double distance;
for (int j = 0; j < buildstate->lists; j++)
{
if (j == i)
continue;
distance = DatumGetFloat8(FunctionCall2Coll(buildstate->procinfo, buildstate->collation, PointerGetDatum(VectorArrayGet(buildstate->centers, i)), PointerGetDatum(VectorArrayGet(buildstate->centers, j))));
distance = (buildstate->listSums[i] + buildstate->listSums[j]) / distance;
if (distance > max)
max = distance;
}
db += max;
}
db /= buildstate->lists;
elog(INFO, "davies-bouldin: %.3f", db);
}
#endif
/* Insert */

2
src/ivfflat.h
View File

@@ -117,6 +117,8 @@ typedef struct IvfflatBuildState
#ifdef IVFFLAT_KMEANS_DEBUG
double inertia;
double *listSums;
int *listCounts;
#endif
/* Sampling */