apaam/mlpack
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

moment expansion works, apparently

Browse Source
This commit is contained in:
Garry Boyer
2007-08-17 18:31:00 +00:00
parent 7083fad7b4
commit 0a6717312a
1 changed files with 51 additions and 68 deletions
Download Patch File Download Diff File Expand all files Collapse all files
fastlib/u/garryb/nbr/tkde.cc
+51 -68
View File
@@ -71,46 +71,6 @@ class Tkde {
}
public:
// Convenience methods for purpose of thresholded KDE
/**
* Compute kernel sum for a region of reference points assuming we have
* the actual query point (not THOR).
*/
double ComputeKernelSum(
const Vector& q,
index_t r_count, const Vector& r_mass, double r_sumsq) const {
double quadratic_term =
+ r_count * la::Dot(q, q)
- 2.0 * la::Dot(q, r_mass)
+ r_sumsq;
return r_count - quadratic_term * kernel.inv_bandwidth_sq();
}
/**
* Divides a vector by an integer (not THOR).
*/
static void ComputeCenter(
index_t count, const Vector& mass, Vector* center) {
DEBUG_ASSERT(count != 0);
center->Copy(mass);
la::Scale(1.0 / count, center);
}
/**
* Compute kernel sum given only a squared distance (not THOR).
*/
double ComputeKernelSum(
double distance_squared,
index_t r_count, const Vector& r_center, double r_sumsq) const {
//q*q - 2qr + rsumsq
//q*q - 2qr + r*r - r*r
double quadratic_term =
(distance_squared - la::Dot(r_center, r_center)) * r_count
+ r_sumsq;
return -quadratic_term * kernel.inv_bandwidth_sq() + r_count;
}
};
@@ -156,23 +116,44 @@ class Tkde {
Add(other.count, other.mass, other.sumsq);
}
double ComputeKernelSum(const Param& param, const Vector& point) const {
return param.ComputeKernelSum(point, count, mass, sumsq);
/**
* Compute kernel sum for a region of reference points assuming we have
* the actual query point.
*/
double ComputeKernelSum(const Param& param, const Vector& q) const {
double quadratic_term =
+ count * la::Dot(q, q)
- 2.0 * la::Dot(q, mass)
+ sumsq;
return count - quadratic_term * param.kernel.inv_bandwidth_sq();
}
double ComputeKernelSum(const Param& param, double distance_squared,
double center_dot_center) const {
//q*q - 2qr + rsumsq
//q*q - 2qr + r*r - r*r
double quadratic_term =
(distance_squared - center_dot_center) * count
+ sumsq;
return -quadratic_term * param.kernel.inv_bandwidth_sq() + count;
}
DRange ComputeKernelSumRange(const Param& param,
const Bound& query_bound) const {
DRange density_bound;
Vector center;
double center_dot_center = la::Dot(mass, mass) / count / count;
DEBUG_ASSERT(count != 0);
param.ComputeCenter(count, mass, &center);
center.Copy(mass);
la::Scale(1.0 / count, &center);
density_bound.lo = param.ComputeKernelSum(
query_bound.MaxDistanceSq(center),
count, center, sumsq);
density_bound.hi = param.ComputeKernelSum(
query_bound.MinDistanceSq(center),
count, center, sumsq);
density_bound.lo = ComputeKernelSum(param,
query_bound.MaxDistanceSq(center), center_dot_center);
density_bound.hi = ComputeKernelSum(param,
query_bound.MinDistanceSq(center), center_dot_center);
return density_bound;
}
@@ -326,10 +307,15 @@ class Tkde {
void Postprocess(const Param& param,
const QPoint& q, index_t q_index,
const RNode& r_root) {
if (density > param.thresh.hi) {
label &= LAB_HI;
} else if (density < param.thresh.lo) {
label &= LAB_LO;
if (label == LAB_EITHER) {
// Only check my density if no prune was made.
// If a prune was made up above, then my density is probably
// out of sync.
if (density > param.thresh.hi) {
label &= LAB_HI;
} else if (density < param.thresh.lo) {
label &= LAB_LO;
}
}
DEBUG_ASSERT_MSG(label != LAB_NEITHER,
"Conflicting labels: %g %g %g",
@@ -406,22 +392,21 @@ class Tkde {
density += delta.d_density;
}
bool ApplyPostponed(const Param& param,
void ApplyPostponed(const Param& param,
const QPostponed& postponed, const QNode& q_node) {
bool change_made;
if (unlikely(postponed.label != LAB_EITHER)) {
label &= postponed.label;
DEBUG_ASSERT(label != LAB_NEITHER);
change_made = true;
}
if (unlikely(!postponed.moment_info.is_empty())) {
density += postponed.moment_info.ComputeKernelSumRange
DRange computed = postponed.moment_info.ComputeKernelSumRange
(param, q_node.bound());
change_made = true;
DEBUG_ASSERT_MSG(computed.lo >= 0, "lo = %g\n", computed.lo);
DEBUG_ASSERT_MSG(computed.hi >= 0, "hi = %g\n", computed.hi);
density += computed;
DEBUG_ASSERT_MSG(density.lo >= 0, "lo = %g\n", density.lo);
DEBUG_ASSERT_MSG(density.hi >= 0, "lo = %g\n", density.hi);
}
return change_made;
}
};
@@ -493,6 +478,8 @@ class Tkde {
QResult* q_result,
GlobalResult* global_result) {
if (unlikely(q_result->label != LAB_EITHER)) {
// We already have a label. It is incorrect to proceed because our
// density values are necessarily invalid.
return false;
}
@@ -570,14 +557,10 @@ class Tkde {
double distance_sq_hi =
q_node.bound().MaxDistanceSq(r_node.bound());
if (0) {
// REMOVED because this was causing bugs.
// Someone please figure out what's wrong with the moment expansion!
/*distance_sq_hi < param.kernel.bandwidth_sq()) {
if (distance_sq_hi < param.kernel.bandwidth_sq()) {
DEBUG_MSG(1.0, "tkde: Inclusion");
q_postponed->moment_info.Add(r_node.stat().moment_info);
need_expansion = false;*/
need_expansion = false;
} else {
DEBUG_MSG(1.0, "tkde: Overlap - need explore");
//delta->d_density = r_node.stat().moment_info.ComputeKernelSumRange(
@@ -614,7 +597,7 @@ class Tkde {
QPostponed* q_postponed) {
bool need_expansion = false;
DEBUG_ASSERT(q_summary_result.density.lo < q_summary_result.density.hi);
DEBUG_ASSERT(q_summary_result.density.lo <= q_summary_result.density.hi);
if (unlikely(q_summary_result.label != LAB_EITHER)) {
DEBUG_ASSERT((q_summary_result.label & q_postponed->label) != LAB_NEITHER);