#include "kd_tree.h"#include "kd_util.h"#include "kd_split.h"Go to the source code of this file.
Functions | |
| void | kd_split (ANNpointArray pa, ANNidxArray pidx, const ANNorthRect &, int n, int dim, int &cut_dim, ANNcoord &cut_val, int &n_lo) |
| void | midpt_split (ANNpointArray pa, ANNidxArray pidx, const ANNorthRect &bnds, int n, int dim, int &cut_dim, ANNcoord &cut_val, int &n_lo) |
| void | sl_midpt_split (ANNpointArray pa, ANNidxArray pidx, const ANNorthRect &bnds, int n, int dim, int &cut_dim, ANNcoord &cut_val, int &n_lo) |
| void | fair_split (ANNpointArray pa, ANNidxArray pidx, const ANNorthRect &bnds, int n, int dim, int &cut_dim, ANNcoord &cut_val, int &n_lo) |
| void | sl_fair_split (ANNpointArray pa, ANNidxArray pidx, const ANNorthRect &bnds, int n, int dim, int &cut_dim, ANNcoord &cut_val, int &n_lo) |
Variables | |
| const double | ERR = 0.001 |
| const double | FS_ASPECT_RATIO = 3.0 |
| void fair_split | ( | ANNpointArray | pa, |
| ANNidxArray | pidx, | ||
| const ANNorthRect & | bnds, | ||
| int | n, | ||
| int | dim, | ||
| int & | cut_dim, | ||
| ANNcoord & | cut_val, | ||
| int & | n_lo | ||
| ) |
Definition at line 243 of file kd_split.cpp.
References annMedianSplit(), annPlaneSplit(), annSplitBalance(), annSpread(), FS_ASPECT_RATIO, ANNorthRect::hi, and ANNorthRect::lo.
Referenced by ANNbd_tree::ANNbd_tree(), and ANNkd_tree::ANNkd_tree().
{
int d;
ANNcoord max_length = bnds.hi[0] - bnds.lo[0];
cut_dim = 0;
for (d = 1; d < dim; d++) { // find length of longest box side
ANNcoord length = bnds.hi[d] - bnds.lo[d];
if (length > max_length) {
max_length = length;
cut_dim = d;
}
}
ANNcoord max_spread = 0; // find legal cut with max spread
cut_dim = 0;
for (d = 0; d < dim; d++) {
ANNcoord length = bnds.hi[d] - bnds.lo[d];
// is this side midpoint splitable
// without violating aspect ratio?
if (((double) max_length)*2.0/((double) length) <= FS_ASPECT_RATIO) {
// compute spread along this dim
ANNcoord spr = annSpread(pa, pidx, n, d);
if (spr > max_spread) { // best spread so far
max_spread = spr;
cut_dim = d; // this is dimension to cut
}
}
}
max_length = 0; // find longest side other than cut_dim
for (d = 0; d < dim; d++) {
ANNcoord length = bnds.hi[d] - bnds.lo[d];
if (d != cut_dim && length > max_length)
max_length = length;
}
// consider most extreme splits
ANNcoord small_piece = (ANNcoord)(max_length / FS_ASPECT_RATIO);
ANNcoord lo_cut = bnds.lo[cut_dim] + small_piece;// lowest legal cut
ANNcoord hi_cut = bnds.hi[cut_dim] - small_piece;// highest legal cut
int br1, br2;
// is median below lo_cut ?
if (annSplitBalance(pa, pidx, n, cut_dim, lo_cut) >= 0) {
cut_val = lo_cut; // cut at lo_cut
annPlaneSplit(pa, pidx, n, cut_dim, cut_val, br1, br2);
n_lo = br1;
}
// is median above hi_cut?
else if (annSplitBalance(pa, pidx, n, cut_dim, hi_cut) <= 0) {
cut_val = hi_cut; // cut at hi_cut
annPlaneSplit(pa, pidx, n, cut_dim, cut_val, br1, br2);
n_lo = br2;
}
else { // median cut preserves asp ratio
n_lo = n/2; // split about median
annMedianSplit(pa, pidx, n, cut_dim, cut_val, n_lo);
}
}
| void kd_split | ( | ANNpointArray | pa, |
| ANNidxArray | pidx, | ||
| const ANNorthRect & | , | ||
| int | n, | ||
| int | dim, | ||
| int & | cut_dim, | ||
| ANNcoord & | cut_val, | ||
| int & | n_lo | ||
| ) |
Definition at line 44 of file kd_split.cpp.
References annMaxSpread(), and annMedianSplit().
Referenced by ANNbd_tree::ANNbd_tree(), and ANNkd_tree::ANNkd_tree().
{
// find dimension of maximum spread
cut_dim = annMaxSpread(pa, pidx, n, dim);
n_lo = n/2; // median rank
// split about median
annMedianSplit(pa, pidx, n, cut_dim, cut_val, n_lo);
}
| void midpt_split | ( | ANNpointArray | pa, |
| ANNidxArray | pidx, | ||
| const ANNorthRect & | bnds, | ||
| int | n, | ||
| int | dim, | ||
| int & | cut_dim, | ||
| ANNcoord & | cut_val, | ||
| int & | n_lo | ||
| ) |
Definition at line 76 of file kd_split.cpp.
References annPlaneSplit(), annSpread(), ERR, ANNorthRect::hi, and ANNorthRect::lo.
Referenced by ANNbd_tree::ANNbd_tree(), and ANNkd_tree::ANNkd_tree().
{
int d;
ANNcoord max_length = bnds.hi[0] - bnds.lo[0];
for (d = 1; d < dim; d++) { // find length of longest box side
ANNcoord length = bnds.hi[d] - bnds.lo[d];
if (length > max_length) {
max_length = length;
}
}
ANNcoord max_spread = -1; // find long side with most spread
for (d = 0; d < dim; d++) {
// is it among longest?
if (double(bnds.hi[d] - bnds.lo[d]) >= (1-ERR)*max_length) {
// compute its spread
ANNcoord spr = annSpread(pa, pidx, n, d);
if (spr > max_spread) { // is it max so far?
max_spread = spr;
cut_dim = d;
}
}
}
// split along cut_dim at midpoint
cut_val = (bnds.lo[cut_dim] + bnds.hi[cut_dim]) / 2;
// permute points accordingly
int br1, br2;
annPlaneSplit(pa, pidx, n, cut_dim, cut_val, br1, br2);
//------------------------------------------------------------------
// On return: pa[0..br1-1] < cut_val
// pa[br1..br2-1] == cut_val
// pa[br2..n-1] > cut_val
//
// We can set n_lo to any value in the range [br1..br2].
// We choose split so that points are most evenly divided.
//------------------------------------------------------------------
if (br1 > n/2) n_lo = br1;
else if (br2 < n/2) n_lo = br2;
else n_lo = n/2;
}
| void sl_fair_split | ( | ANNpointArray | pa, |
| ANNidxArray | pidx, | ||
| const ANNorthRect & | bnds, | ||
| int | n, | ||
| int | dim, | ||
| int & | cut_dim, | ||
| ANNcoord & | cut_val, | ||
| int & | n_lo | ||
| ) |
Definition at line 346 of file kd_split.cpp.
References annMedianSplit(), annMinMax(), annPlaneSplit(), annSplitBalance(), annSpread(), FS_ASPECT_RATIO, ANNorthRect::hi, ANNorthRect::lo, QuadProgPP::max(), and min.
Referenced by ANNbd_tree::ANNbd_tree(), and ANNkd_tree::ANNkd_tree().
{
int d;
ANNcoord min, max; // min/max coordinates
int br1, br2; // split break points
ANNcoord max_length = bnds.hi[0] - bnds.lo[0];
cut_dim = 0;
for (d = 1; d < dim; d++) { // find length of longest box side
ANNcoord length = bnds.hi[d] - bnds.lo[d];
if (length > max_length) {
max_length = length;
cut_dim = d;
}
}
ANNcoord max_spread = 0; // find legal cut with max spread
cut_dim = 0;
for (d = 0; d < dim; d++) {
ANNcoord length = bnds.hi[d] - bnds.lo[d];
// is this side midpoint splitable
// without violating aspect ratio?
if (((double) max_length)*2.0/((double) length) <= FS_ASPECT_RATIO) {
// compute spread along this dim
ANNcoord spr = annSpread(pa, pidx, n, d);
if (spr > max_spread) { // best spread so far
max_spread = spr;
cut_dim = d; // this is dimension to cut
}
}
}
max_length = 0; // find longest side other than cut_dim
for (d = 0; d < dim; d++) {
ANNcoord length = bnds.hi[d] - bnds.lo[d];
if (d != cut_dim && length > max_length)
max_length = length;
}
// consider most extreme splits
ANNcoord small_piece = (ANNcoord)(max_length / FS_ASPECT_RATIO);
ANNcoord lo_cut = bnds.lo[cut_dim] + small_piece;// lowest legal cut
ANNcoord hi_cut = bnds.hi[cut_dim] - small_piece;// highest legal cut
// find min and max along cut_dim
annMinMax(pa, pidx, n, cut_dim, min, max);
// is median below lo_cut?
if (annSplitBalance(pa, pidx, n, cut_dim, lo_cut) >= 0) {
if (max > lo_cut) { // are any points above lo_cut?
cut_val = lo_cut; // cut at lo_cut
annPlaneSplit(pa, pidx, n, cut_dim, cut_val, br1, br2);
n_lo = br1; // balance if there are ties
}
else { // all points below lo_cut
cut_val = max; // cut at max value
annPlaneSplit(pa, pidx, n, cut_dim, cut_val, br1, br2);
n_lo = n-1;
}
}
// is median above hi_cut?
else if (annSplitBalance(pa, pidx, n, cut_dim, hi_cut) <= 0) {
if (min < hi_cut) { // are any points below hi_cut?
cut_val = hi_cut; // cut at hi_cut
annPlaneSplit(pa, pidx, n, cut_dim, cut_val, br1, br2);
n_lo = br2; // balance if there are ties
}
else { // all points above hi_cut
cut_val = min; // cut at min value
annPlaneSplit(pa, pidx, n, cut_dim, cut_val, br1, br2);
n_lo = 1;
}
}
else { // median cut is good enough
n_lo = n/2; // split about median
annMedianSplit(pa, pidx, n, cut_dim, cut_val, n_lo);
}
}
| void sl_midpt_split | ( | ANNpointArray | pa, |
| ANNidxArray | pidx, | ||
| const ANNorthRect & | bnds, | ||
| int | n, | ||
| int | dim, | ||
| int & | cut_dim, | ||
| ANNcoord & | cut_val, | ||
| int & | n_lo | ||
| ) |
Definition at line 146 of file kd_split.cpp.
References annMinMax(), annPlaneSplit(), annSpread(), ERR, ANNorthRect::hi, ANNorthRect::lo, QuadProgPP::max(), and min.
Referenced by ANNbd_tree::ANNbd_tree(), and ANNkd_tree::ANNkd_tree().
{
int d;
ANNcoord max_length = bnds.hi[0] - bnds.lo[0];
for (d = 1; d < dim; d++) { // find length of longest box side
ANNcoord length = bnds.hi[d] - bnds.lo[d];
if (length > max_length) {
max_length = length;
}
}
ANNcoord max_spread = -1; // find long side with most spread
for (d = 0; d < dim; d++) {
// is it among longest?
if ((bnds.hi[d] - bnds.lo[d]) >= (1-ERR)*max_length) {
// compute its spread
ANNcoord spr = annSpread(pa, pidx, n, d);
if (spr > max_spread) { // is it max so far?
max_spread = spr;
cut_dim = d;
}
}
}
// ideal split at midpoint
ANNcoord ideal_cut_val = (bnds.lo[cut_dim] + bnds.hi[cut_dim])/2;
ANNcoord min, max;
annMinMax(pa, pidx, n, cut_dim, min, max); // find min/max coordinates
if (ideal_cut_val < min) // slide to min or max as needed
cut_val = min;
else if (ideal_cut_val > max)
cut_val = max;
else
cut_val = ideal_cut_val;
// permute points accordingly
int br1, br2;
annPlaneSplit(pa, pidx, n, cut_dim, cut_val, br1, br2);
//------------------------------------------------------------------
// On return: pa[0..br1-1] < cut_val
// pa[br1..br2-1] == cut_val
// pa[br2..n-1] > cut_val
//
// We can set n_lo to any value in the range [br1..br2] to satisfy
// the exit conditions of the procedure.
//
// if ideal_cut_val < min (implying br2 >= 1),
// then we select n_lo = 1 (so there is one point on left) and
// if ideal_cut_val > max (implying br1 <= n-1),
// then we select n_lo = n-1 (so there is one point on right).
// Otherwise, we select n_lo as close to n/2 as possible within
// [br1..br2].
//------------------------------------------------------------------
if (ideal_cut_val < min) n_lo = 1;
else if (ideal_cut_val > max) n_lo = n-1;
else if (br1 > n/2) n_lo = br1;
else if (br2 < n/2) n_lo = br2;
else n_lo = n/2;
}
| const double ERR = 0.001 |
Definition at line 34 of file kd_split.cpp.
Referenced by midpt_split(), and sl_midpt_split().
| const double FS_ASPECT_RATIO = 3.0 |
Definition at line 35 of file kd_split.cpp.
Referenced by fair_split(), and sl_fair_split().
1.7.2