//----------------------------------------------------------------------
// swapOneCenter
// Swaps one center point with a sample point. Optionally we make
// sure that the new point is not a duplicate of any of the centers
// (including the point being replaced).
//----------------------------------------------------------------------
void KMfilterCenters::swapOneCenter( // swap one center
bool allowDuplicate) // allow duplicate centers
{
int rj = kmRanInt(kCtrs); // index of center to replace
int dim = getDim();
KMpoint p = kmAllocPt(dim); // alloc replacement point
pts->sampleCtr(p); // sample a replacement
if (!allowDuplicate) { // duplicates not allowed?
bool dupFound; // was a duplicate found?
do { // repeat until successful
dupFound = false;
for (int j = 0; j < kCtrs; j++) { // search for duplicates
if (kmEqualPts(dim, p, ctrs[j])) {
dupFound = true;
pts->sampleCtr(p); // try again
break;
}
}
} while (dupFound);
}
kmCopyPt(dim, p, ctrs[rj]); // copy sampled point
if (kmStatLev >= STEP) { // output swap info
*kmOut << "\tswapping: ";
kmPrintPt(p, getDim(), true);
*kmOut << "<-->Center[" << rj << "]\n";
}
kmDeallocPt(p); // deallocate point storage
invalidate(); // distortions now invalid
}
static void initDistGlobals( // initialize distortion globals
KMfilterCenters& ctrs) // the centers
{
initBasicGlobals(ctrs.getDim(), ctrs.getNPts(), ctrs.getDataPts());
kcKCtrs = ctrs.getK();
kcCenters = ctrs.getCtrPts(); // get ptrs to KMcenter arrays
kcWeights = ctrs.getWeights(false);
kcSums = ctrs.getSums(false);
kcSumSqs = ctrs.getSumSqs(false);
kcDists = ctrs.getDists(false);
kcBoxMidpt = kmAllocPt(kcDim);
for (int j = 0; j < kcKCtrs; j++) { // initialize sums
kcWeights[j] = 0;
kcSumSqs[j] = 0;
for (int d = 0; d < kcDim; d++) {
kcSums[j][d] = 0;
}
}
}
void kmMultiClus( // multi-sized clusters
KMpointArray pa, // point array (modified)
int n, // number of points
int dim, // dimension
int &k, // number of clusters (returned)
double base_dev) // base standard deviation
{
int next = 0; // next point in array
int nSamp = 0; // number of points sampled
k = 0; // number of clusters generated
KMpoint clusCenter = kmAllocPt(dim); // allocate center storage
while (nSamp < n) { // until we have sampled enough
int remain = n - nSamp; // number remaining to sample
int clusSize = 2;
// repeatedly double cluster size
// with prob 1/2
while ((clusSize < remain) && (kmRan0() < 0.5))
clusSize *= 2;
// don't exceed upper limit
if (clusSize > remain) clusSize = remain;
// generate center uniformly
for (int d = 0; d < dim; d++) {
clusCenter[d] = (KMcoord) kmRanUnif(-1,1);
}
// desired std dev for cluster
double stdDev = base_dev*sqrt(1.0/clusSize);
// generate cluster points
for (int i = 0; i < clusSize; i++) {
for (int d = 0; d < dim; d++) {
pa[next][d] = (KMcoord) (stdDev*kmRanGauss()+clusCenter[d]);
}
next++;
}
nSamp += clusSize; // update number sampled
k++; // one more cluster
}
kmDeallocPt(clusCenter);
}
