↰ Return to documentation for file (include/networkit/generators/quadtree/QuadNodePolarEuclid.hpp)
/*
* QuadNodePolarEuclid.hpp
*
* Created on: 21.05.2014
* Author: Moritz v. Looz
*
* Note: This is similar enough to QuadNode.hpp that one could merge these two classes.
*/
#ifndef NETWORKIT_GENERATORS_QUADTREE_QUAD_NODE_POLAR_EUCLID_HPP_
#define NETWORKIT_GENERATORS_QUADTREE_QUAD_NODE_POLAR_EUCLID_HPP_
#include <algorithm>
#include <cassert>
#include <functional>
#include <vector>
#include <networkit/auxiliary/Log.hpp>
#include <networkit/geometric/HyperbolicSpace.hpp>
namespace NetworKit {
template <class T>
class QuadNodePolarEuclid final {
friend class QuadTreeGTest;
double leftAngle;
double minR;
double rightAngle;
double maxR;
Point2DWithIndex<double> a, b, c, d;
unsigned capacity;
static const unsigned coarsenLimit = 4;
count subTreeSize;
std::vector<T> content;
std::vector<Point2DWithIndex<double>> positions;
std::vector<double> angles;
std::vector<double> radii;
bool isLeaf;
bool splitTheoretical;
double balance;
index ID;
double lowerBoundR;
public:
std::vector<QuadNodePolarEuclid> children;
QuadNodePolarEuclid() {
// This should never be called.
leftAngle = 0;
rightAngle = 0;
minR = 0;
maxR = 0;
capacity = 20;
isLeaf = true;
subTreeSize = 0;
balance = 0.5;
splitTheoretical = false;
lowerBoundR = maxR;
ID = 0;
}
QuadNodePolarEuclid(double leftAngle, double minR, double rightAngle, double maxR,
unsigned capacity = 1000, bool splitTheoretical = false,
double balance = 0.5) {
if (balance <= 0 || balance >= 1)
throw std::runtime_error("Quadtree balance parameter must be between 0 and 1.");
this->leftAngle = leftAngle;
this->minR = minR;
this->maxR = maxR;
this->rightAngle = rightAngle;
this->a = HyperbolicSpace::polarToCartesian(leftAngle, minR);
this->b = HyperbolicSpace::polarToCartesian(rightAngle, minR);
this->c = HyperbolicSpace::polarToCartesian(rightAngle, maxR);
this->d = HyperbolicSpace::polarToCartesian(leftAngle, maxR);
this->capacity = capacity;
this->splitTheoretical = splitTheoretical;
this->balance = balance;
this->lowerBoundR = maxR;
this->ID = 0;
isLeaf = true;
subTreeSize = 0;
}
void split() {
assert(isLeaf);
// heavy lifting: split up!
double middleAngle, middleR;
if (splitTheoretical) {
// Euclidean space is distributed equally
middleAngle = (rightAngle - leftAngle) / 2 + leftAngle;
middleR = std::pow(maxR * maxR * (1 - balance) + minR * minR * balance, 0.5);
} else {
// median of points
vector<double> sortedAngles = angles;
std::sort(sortedAngles.begin(), sortedAngles.end());
middleAngle = sortedAngles[sortedAngles.size() / 2];
vector<double> sortedRadii = radii;
std::sort(sortedRadii.begin(), sortedRadii.end());
middleR = sortedRadii[sortedRadii.size() / 2];
}
assert(middleR < maxR);
assert(middleR > minR);
QuadNodePolarEuclid southwest(leftAngle, minR, middleAngle, middleR, capacity,
splitTheoretical, balance);
QuadNodePolarEuclid southeast(middleAngle, minR, rightAngle, middleR, capacity,
splitTheoretical, balance);
QuadNodePolarEuclid northwest(leftAngle, middleR, middleAngle, maxR, capacity,
splitTheoretical, balance);
QuadNodePolarEuclid northeast(middleAngle, middleR, rightAngle, maxR, capacity,
splitTheoretical, balance);
children = {southwest, southeast, northwest, northeast};
isLeaf = false;
}
void addContent(T input, double angle, double R) {
assert(this->responsible(angle, R));
if (lowerBoundR > R)
lowerBoundR = R;
if (isLeaf) {
if (content.size() + 1 < capacity) {
content.push_back(input);
angles.push_back(angle);
radii.push_back(R);
Point2DWithIndex<double> pos = HyperbolicSpace::polarToCartesian(angle, R);
positions.push_back(pos);
} else {
split();
for (index i = 0; i < content.size(); i++) {
this->addContent(content[i], angles[i], radii[i]);
}
assert(subTreeSize == content.size()); // we have added everything twice
subTreeSize = content.size();
content.clear();
angles.clear();
radii.clear();
positions.clear();
this->addContent(input, angle, R);
}
} else {
assert(children.size() > 0);
for (auto &child : children)
if (child.responsible(angle, R)) {
child.addContent(input, angle, R);
break;
}
subTreeSize++;
}
}
bool removeContent(T input, double angle, double R) {
if (!responsible(angle, R))
return false;
if (isLeaf) {
index i = 0;
for (; i < content.size(); i++) {
if (content[i] == input)
break;
}
if (i < content.size()) {
assert(angles[i] == angle);
assert(radii[i] == R);
// remove element
content.erase(content.begin() + i);
positions.erase(positions.begin() + i);
angles.erase(angles.begin() + i);
radii.erase(radii.begin() + i);
return true;
} else {
return false;
}
} else {
bool removed = false;
bool allLeaves = true;
assert(children.size() > 0);
for (index i = 0; i < children.size(); i++) {
if (!children[i].isLeaf)
allLeaves = false;
if (children[i].removeContent(input, angle, R)) {
assert(!removed);
removed = true;
}
}
if (removed)
subTreeSize--;
// coarsen?
if (removed && allLeaves && size() < coarsenLimit) {
// coarsen!!
// why not assert empty containers and then insert directly?
vector<T> allContent;
vector<Point2DWithIndex<double>> allPositions;
vector<double> allAngles;
vector<double> allRadii;
for (index i = 0; i < children.size(); i++) {
allContent.insert(allContent.end(), children[i].content.begin(),
children[i].content.end());
allPositions.insert(allPositions.end(), children[i].positions.begin(),
children[i].positions.end());
allAngles.insert(allAngles.end(), children[i].angles.begin(),
children[i].angles.end());
allRadii.insert(allRadii.end(), children[i].radii.begin(),
children[i].radii.end());
}
assert(subTreeSize == allContent.size());
assert(subTreeSize == allPositions.size());
assert(subTreeSize == allAngles.size());
assert(subTreeSize == allRadii.size());
children.clear();
content.swap(allContent);
positions.swap(allPositions);
angles.swap(allAngles);
radii.swap(allRadii);
isLeaf = true;
}
return removed;
}
}
bool outOfReach(Point2DWithIndex<double> query, double radius) const {
double phi, r;
HyperbolicSpace::cartesianToPolar(query, phi, r);
if (responsible(phi, r))
return false;
// get four edge points
double topDistance, bottomDistance, leftDistance, rightDistance;
if (phi < leftAngle || phi > rightAngle) {
topDistance = std::min(c.distance(query), d.distance(query));
} else {
topDistance = std::abs(r - maxR);
}
if (topDistance <= radius)
return false;
if (phi < leftAngle || phi > rightAngle) {
bottomDistance = std::min(a.distance(query), b.distance(query));
} else {
bottomDistance = std::abs(r - minR);
}
if (bottomDistance <= radius)
return false;
double minDistanceR = r * std::cos(std::abs(phi - leftAngle));
if (minDistanceR > minR && minDistanceR < maxR) {
leftDistance = query.distance(HyperbolicSpace::polarToCartesian(phi, minDistanceR));
} else {
leftDistance = std::min(a.distance(query), d.distance(query));
}
if (leftDistance <= radius)
return false;
minDistanceR = r * std::cos(std::abs(phi - rightAngle));
if (minDistanceR > minR && minDistanceR < maxR) {
rightDistance = query.distance(HyperbolicSpace::polarToCartesian(phi, minDistanceR));
} else {
rightDistance = std::min(b.distance(query), c.distance(query));
}
if (rightDistance <= radius)
return false;
return true;
}
bool outOfReach(double angle_c, double r_c, double radius) const {
if (responsible(angle_c, r_c))
return false;
Point2DWithIndex<double> query = HyperbolicSpace::polarToCartesian(angle_c, r_c);
return outOfReach(query, radius);
}
std::pair<double, double> EuclideanDistances(double phi, double r) const {
double maxDistance = 0;
double minDistance = std::numeric_limits<double>::max();
if (responsible(phi, r))
minDistance = 0;
auto euclidDistancePolar = [](double phi_a, double r_a, double phi_b, double r_b) {
return std::pow(r_a * r_a + r_b * r_b - 2 * r_a * r_b * std::cos(phi_a - phi_b), 0.5);
};
auto updateMinMax = [&minDistance, &maxDistance, phi, r, euclidDistancePolar](double phi_b,
double r_b) {
double extremalValue = euclidDistancePolar(phi, r, phi_b, r_b);
// assert(extremalValue <= r + r_b);
maxDistance = std::max(extremalValue, maxDistance);
minDistance = std::min(minDistance, extremalValue);
};
// left
double extremum = r * std::cos(this->leftAngle - phi);
if (extremum < maxR && extremum > minR) {
updateMinMax(this->leftAngle, extremum);
}
// right
extremum = r * std::cos(this->rightAngle - phi);
if (extremum < maxR && extremum > minR) {
updateMinMax(this->leftAngle, extremum);
}
if (phi > leftAngle && phi < rightAngle) {
updateMinMax(phi, maxR);
updateMinMax(phi, minR);
}
if (phi + PI > leftAngle && phi + PI < rightAngle) {
updateMinMax(phi + PI, maxR);
updateMinMax(phi + PI, minR);
}
if (phi - PI > leftAngle && phi - PI < rightAngle) {
updateMinMax(phi - PI, maxR);
updateMinMax(phi - PI, minR);
}
updateMinMax(leftAngle, maxR);
updateMinMax(rightAngle, maxR);
updateMinMax(leftAngle, minR);
updateMinMax(rightAngle, minR);
assert(minDistance < maxDistance);
return std::pair<double, double>(minDistance, maxDistance);
}
bool responsible(double angle, double r) const {
return (angle >= leftAngle && angle < rightAngle && r >= minR && r < maxR);
}
std::vector<T> getElements() const {
if (isLeaf) {
return content;
} else {
assert(content.size() == 0);
assert(angles.size() == 0);
assert(radii.size() == 0);
vector<T> result;
for (const auto &child : children) {
std::vector<T> subresult = child.getElements();
result.insert(result.end(), subresult.begin(), subresult.end());
}
return result;
}
}
void getCoordinates(vector<double> &anglesContainer, vector<double> &radiiContainer) const {
assert(angles.size() == radii.size());
if (isLeaf) {
anglesContainer.insert(anglesContainer.end(), angles.begin(), angles.end());
radiiContainer.insert(radiiContainer.end(), radii.begin(), radii.end());
} else {
assert(content.size() == 0);
assert(angles.size() == 0);
assert(radii.size() == 0);
for (const auto &child : children)
child.getCoordinates(anglesContainer, radiiContainer);
}
}
void getElementsInEuclideanCircle(Point2DWithIndex<double> center, double radius,
vector<T> &result, double minAngle = 0,
double maxAngle = 2 * PI, double lowR = 0,
double highR = 1) const {
if (minAngle >= rightAngle || maxAngle <= leftAngle || lowR >= maxR || highR < lowerBoundR)
return;
if (outOfReach(center, radius)) {
return;
}
if (isLeaf) {
const double rsq = radius * radius;
const double queryX = center[0];
const double queryY = center[1];
const count cSize = content.size();
for (int i = 0; i < cSize; i++) {
const double deltaX = positions[i].getX() - queryX;
const double deltaY = positions[i].getY() - queryY;
if (deltaX * deltaX + deltaY * deltaY < rsq) {
result.push_back(content[i]);
}
}
} else {
for (const auto &child : children)
child.getElementsInEuclideanCircle(center, radius, result, minAngle, maxAngle, lowR,
highR);
}
}
count getElementsProbabilistically(Point2DWithIndex<double> euQuery,
std::function<double(double)> prob, bool suppressLeft,
vector<T> &result) const {
double phi_q, r_q;
HyperbolicSpace::cartesianToPolar(euQuery, phi_q, r_q);
if (suppressLeft && phi_q > rightAngle)
return 0;
TRACE("Getting Euclidean distances");
auto distancePair = EuclideanDistances(phi_q, r_q);
double probUB = prob(distancePair.first);
assert(prob(distancePair.second) <= probUB);
if (probUB > 0.5)
probUB = 1; // if we are going to take every second element anyway, no use in
// calculating expensive jumps
if (probUB == 0)
return 0;
// TODO: return whole if probLB == 1
double probdenom = std::log(1 - probUB);
if (probdenom == 0) {
DEBUG(probUB, " not zero, but too small too process. Ignoring.");
return 0;
}
TRACE("probUB: ", probUB, ", probdenom: ", probdenom);
count expectedNeighbours = probUB * size();
count candidatesTested = 0;
if (isLeaf) {
const count lsize = content.size();
TRACE("Leaf of size ", lsize);
for (index i = 0; i < lsize; i++) {
// jump!
if (probUB < 1) {
double random = Aux::Random::real();
double delta = std::log(random) / probdenom;
assert(delta == delta);
assert(delta >= 0);
i += delta;
if (i >= lsize)
break;
TRACE("Jumped with delta ", delta, " arrived at ", i);
}
// see where we've arrived
candidatesTested++;
double distance = positions[i].distance(euQuery);
double q = prob(distance);
q = q / probUB; // since the candidate was selected by the jumping process, we have
// to adjust the probabilities
assert(q <= 1);
assert(q >= 0);
// accept?
double acc = Aux::Random::real();
if (acc < q) {
TRACE("Accepted node ", i, " with probability ", q, ".");
result.push_back(content[i]);
}
}
} else {
if (expectedNeighbours < 4
|| probUB < 1 / 1000) { // select candidates directly instead of calling recursively
TRACE("probUB = ", probUB, ", switching to direct candidate selection.");
assert(probUB < 1);
const count stsize = size();
for (index i = 0; i < stsize; i++) {
double delta = std::log(Aux::Random::real()) / probdenom;
assert(delta >= 0);
i += delta;
TRACE("Jumped with delta ", delta, " arrived at ", i,
". Calling maybeGetKthElement.");
if (i < size())
maybeGetKthElement(
probUB, euQuery, prob, i,
result); // this could be optimized. As of now, the offset is subtracted
// separately for each point
else
break;
candidatesTested++;
}
} else { // carry on as normal
for (index i = 0; i < children.size(); i++) {
TRACE("Recursively calling child ", i);
candidatesTested += children[i].getElementsProbabilistically(
euQuery, prob, suppressLeft, result);
}
}
}
return candidatesTested;
}
void maybeGetKthElement(double upperBound, Point2DWithIndex<double> euQuery,
std::function<double(double)> prob, index k,
vector<T> &circleDenizens) const {
TRACE("Maybe get element ", k, " with upper Bound ", upperBound);
assert(k < size());
if (isLeaf) {
double acceptance = prob(euQuery.distance(positions[k])) / upperBound;
TRACE("Is leaf, accept with ", acceptance);
if (Aux::Random::real() < acceptance)
circleDenizens.push_back(content[k]);
} else {
TRACE("Call recursively.");
index offset = 0;
for (index i = 0; i < children.size(); i++) {
count childsize = children[i].size();
if (k - offset < childsize) {
children[i].maybeGetKthElement(upperBound, euQuery, prob, k - offset,
circleDenizens);
break;
}
offset += childsize;
}
}
}
void trim() {
content.shrink_to_fit();
positions.shrink_to_fit();
angles.shrink_to_fit();
radii.shrink_to_fit();
if (!isLeaf) {
for (index i = 0; i < children.size(); i++) {
children[i].trim();
}
}
}
count size() const { return isLeaf ? content.size() : subTreeSize; }
void recount() {
subTreeSize = 0;
for (index i = 0; i < children.size(); i++) {
children[i].recount();
subTreeSize += children[i].size();
}
}
count height() const {
count result = 1; // if leaf node, the children loop will not execute
for (const auto &child : children)
result = std::max(result, child.height() + 1);
return std::max(count{1}, result);
}
count countLeaves() const {
if (isLeaf)
return 1;
return std::accumulate(children.begin(), children.end(), count{0},
[](const auto &child) -> count { return child.countLeaves(); });
}
double getLeftAngle() const { return leftAngle; }
double getRightAngle() const { return rightAngle; }
double getMinR() const { return minR; }
double getMaxR() const { return maxR; }
index getID() const { return ID; }
index indexSubtree(index nextID) {
index result = nextID;
assert(children.size() == 4 || children.size() == 0);
for (int i = 0; i < children.size(); i++) {
result = children[i].indexSubtree(result);
}
this->ID = result;
return result + 1;
}
index getCellID(double phi, double r) const {
if (!responsible(phi, r))
return none;
if (isLeaf)
return getID();
else {
for (const auto &child : children) {
index childresult = child.getCellID(phi, r);
if (childresult != none)
return childresult;
}
throw std::runtime_error(
"No responsible child node found even though this node is responsible.");
}
}
index getMaxIDInSubtree() const {
if (isLeaf)
return getID();
else {
index result = 0;
for (int i = 0; i < 4; i++) {
result = std::max(children[i].getMaxIDInSubtree(), result);
}
return std::max(result, getID());
}
}
count reindex(count offset) {
if (isLeaf) {
#ifndef NETWORKIT_OMP2
#pragma omp task
#endif // NETWORKIT_OMP2
{
index p = offset;
std::generate(content.begin(), content.end(), [&p]() { return p++; });
}
offset += size();
} else {
for (int i = 0; i < 4; i++) {
offset = children[i].reindex(offset);
}
}
return offset;
}
};
} // namespace NetworKit
#endif // NETWORKIT_GENERATORS_QUADTREE_QUAD_NODE_POLAR_EUCLID_HPP_