mapnik/deps/boost/geometry/extensions/index/rtree/rtree.hpp
2014-10-22 23:51:44 -07:00

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24 KiB
C++

// Boost.Geometry (aka GGL, Generic Geometry Library)
// Boost.SpatialIndex - rtree implementation
//
// Copyright 2008 Federico J. Fernandez.
// Use, modification and distribution is subject to the Boost Software License,
// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_GEOMETRY_EXTENSIONS_INDEX_RTREE_RTREE_HPP
#define BOOST_GEOMETRY_EXTENSIONS_INDEX_RTREE_RTREE_HPP
#include <cstddef>
#include <iostream> // TODO: Remove if print() is removed
#include <stdexcept>
#include <utility>
#include <vector>
#include <boost/concept_check.hpp>
#include <memory>
#include <boost/geometry/algorithms/area.hpp>
#include <boost/geometry/extensions/index/rtree/rtree_node.hpp>
#include <boost/geometry/extensions/index/rtree/rtree_leaf.hpp>
namespace boost { namespace geometry { namespace index
{
template <typename Box, typename Value >
class rtree
{
public:
typedef std::shared_ptr<rtree_node<Box, Value> > node_pointer;
typedef std::shared_ptr<rtree_leaf<Box, Value> > leaf_pointer;
/**
* \brief Creates a rtree with 'maximum' elements per node and 'minimum'.
*/
rtree(unsigned int const& maximum, unsigned int const& minimum)
: m_count(0)
, m_min_elems_per_node(minimum)
, m_max_elems_per_node(maximum)
, m_root(new rtree_node<Box, Value>(node_pointer(), 1))
{
}
/**
* \brief Creates a rtree with maximum elements per node
* and minimum (box is ignored).
*/
rtree(Box const& box, unsigned int const& maximum, unsigned int const& minimum)
: m_count(0)
, m_min_elems_per_node(minimum)
, m_max_elems_per_node(maximum)
, m_root(new rtree_node<Box, Value>(node_pointer(), 1))
{
boost::ignore_unused_variable_warning(box);
}
/**
* \brief destructor (virtual because we have virtual functions)
*/
virtual ~rtree() {}
/**
* \brief Remove elements inside the 'box'
*/
inline void remove(Box const& box)
{
try
{
node_pointer leaf(choose_exact_leaf(box));
typename rtree_leaf<Box, Value>::leaf_map q_leaves;
leaf->remove(box);
if (leaf->elements() < m_min_elems_per_node && elements() > m_min_elems_per_node)
{
q_leaves = leaf->get_leaves();
// we remove the leaf_node in the parent node because now it's empty
leaf->get_parent()->remove(leaf->get_parent()->get_box(leaf));
}
typename rtree_node<Box, Value>::node_map q_nodes;
condense_tree(leaf, q_nodes);
std::vector<std::pair<Box, Value> > s;
for (typename rtree_node<Box, Value>::node_map::const_iterator it = q_nodes.begin();
it != q_nodes.end(); ++it)
{
typename rtree_leaf<Box, Value>::leaf_map leaves = it->second->get_leaves();
// reinserting leaves from nodes
for (typename rtree_leaf<Box, Value>::leaf_map::const_iterator itl = leaves.begin();
itl != leaves.end(); ++itl)
{
s.push_back(*itl);
}
}
for (typename std::vector<std::pair<Box, Value> >::const_iterator it = s.begin(); it != s.end(); ++it)
{
m_count--;
insert(it->first, it->second);
}
// if the root has only one child and the child is not a leaf,
// make it the root
if (m_root->elements() == 1)
{
if (!m_root->first_element()->is_leaf())
{
m_root = m_root->first_element();
}
}
// reinserting leaves
for (typename rtree_leaf<Box, Value>::leaf_map::const_iterator it = q_leaves.begin();
it != q_leaves.end(); ++it)
{
m_count--;
insert(it->first, it->second);
}
m_count--;
}
catch(std::logic_error & e)
{
// TODO: mloskot - replace with Boost.Geometry exception
// not found
std::cerr << e.what() << std::endl;
return;
}
}
/**
* \brief Remove element inside the box with value
*/
void remove(Box const& box, Value const& value)
{
try
{
node_pointer leaf;
// find possible leaves
typedef typename std::vector<node_pointer > node_type;
node_type nodes;
m_root->find_leaves(box, nodes);
// refine the result
for (typename node_type::const_iterator it = nodes.begin(); it != nodes.end(); ++it)
{
leaf = *it;
try
{
leaf->remove(value);
break;
} catch (...)
{
leaf = node_pointer();
}
}
if (!leaf)
return;
typename rtree_leaf < Box, Value >::leaf_map q_leaves;
if (leaf->elements() < m_min_elems_per_node && elements() > m_min_elems_per_node)
{
q_leaves = leaf->get_leaves();
// we remove the leaf_node in the parent node because now it's empty
leaf->get_parent()->remove(leaf->get_parent()->get_box(leaf));
}
typename rtree_node<Box, Value>::node_map q_nodes;
condense_tree(leaf, q_nodes);
std::vector<std::pair<Box, Value> > s;
for (typename rtree_node<Box, Value>::node_map::const_iterator it = q_nodes.begin();
it != q_nodes.end(); ++it)
{
typename rtree_leaf<Box, Value>::leaf_map leaves = it->second->get_leaves();
// reinserting leaves from nodes
for (typename rtree_leaf<Box, Value>::leaf_map::const_iterator itl = leaves.begin();
itl != leaves.end(); ++itl)
{
s.push_back(*itl);
}
}
for (typename std::vector<std::pair<Box, Value> >::const_iterator it = s.begin(); it != s.end(); ++it)
{
m_count--;
insert(it->first, it->second);
}
// if the root has only one child and the child is not a leaf,
// make it the root
if (m_root->elements() == 1)
{
if (!m_root->first_element()->is_leaf())
{
m_root = m_root->first_element();
}
}
// reinserting leaves
for (typename rtree_leaf<Box, Value>::leaf_map::const_iterator it = q_leaves.begin();
it != q_leaves.end(); ++it)
{
m_count--;
insert(it->first, it->second);
}
m_count--;
}
catch(std::logic_error & e)
{
// TODO: mloskot - ggl exception
// not found
std::cerr << e.what() << std::endl;
return;
}
}
/**
* \brief Returns the number of elements.
*/
inline unsigned int elements() const
{
return m_count;
}
/**
* \brief Inserts an element with 'box' as key with value.
*/
inline void insert(Box const& box, Value const& value)
{
m_count++;
node_pointer leaf(choose_corresponding_leaf(box));
// check if the selected leaf is full to do the split if necessary
if (leaf->elements() >= m_max_elems_per_node)
{
leaf->insert(box, value);
// split!
node_pointer n1(new rtree_leaf<Box, Value>(leaf->get_parent()));
node_pointer n2(new rtree_leaf<Box, Value>(leaf->get_parent()));
split_node(leaf, n1, n2);
adjust_tree(leaf, n1, n2);
}
else
{
leaf->insert(box, value);
adjust_tree(leaf);
}
}
/**
* \brief Returns all the values inside 'box'
*/
inline std::deque<Value> find(Box const& box) const
{
std::deque<Value> result;
m_root->find(box, result, false);
return result;
}
/**
* \brief Print Rtree (mainly for debug)
*/
inline void print()
{
std::cerr << "===================================" << std::endl;
std::cerr << " Min/Max: " << m_min_elems_per_node << " / " << m_max_elems_per_node << std::endl;
std::cerr << "Leaves: " << m_root->get_leaves().size() << std::endl;
m_root->print();
std::cerr << "===================================" << std::endl;
}
private:
/// number of elements
unsigned int m_count;
/// minimum number of elements per node
unsigned int m_min_elems_per_node;
/// maximum number of elements per node
unsigned int m_max_elems_per_node;
/// tree root
node_pointer m_root;
/**
* \brief Reorganize the tree after a removal. It tries to
* join nodes with less elements than m.
*/
void condense_tree(node_pointer const& leaf,
typename rtree_node<Box, Value>::node_map& q_nodes)
{
if (leaf.get() == m_root.get())
{
// if it's the root we are done
return;
}
node_pointer parent = leaf->get_parent();
parent->adjust_box(leaf);
if (parent->elements() < m_min_elems_per_node)
{
if (parent.get() == m_root.get())
{
// if the parent is underfull and it's the root we just exit
return;
}
// get the nodes that we should reinsert
typename rtree_node<Box, Value>::node_map this_nodes = parent->get_nodes();
for(typename rtree_node<Box, Value>::node_map::const_iterator it = this_nodes.begin();
it != this_nodes.end(); ++it)
{
q_nodes.push_back(*it);
}
// we remove the node in the parent node because now it should be
// re inserted
parent->get_parent()->remove(parent->get_parent()->get_box(parent));
}
condense_tree(parent, q_nodes);
}
/**
* \brief After an insertion splits nodes with more than 'maximum' elements.
*/
inline void adjust_tree(node_pointer& node)
{
if (node.get() == m_root.get())
{
// we finished the adjust
return;
}
// as there are no splits just adjust the box of the parent and go on
node_pointer parent = node->get_parent();
parent->adjust_box(node);
adjust_tree(parent);
}
/**
* \brief After an insertion splits nodes with more than maximum elements
* (recursive step with subtrees 'n1' and 'n2' to be joined).
*/
void adjust_tree(node_pointer& leaf, node_pointer& n1, node_pointer& n2)
{
// check if we are in the root and do the split
if (leaf.get() == m_root.get())
{
node_pointer new_root(new rtree_node<Box,Value>(node_pointer (), leaf->get_level() + 1));
new_root->add_node(n1->compute_box(), n1);
new_root->add_node(n2->compute_box(), n2);
n1->set_parent(new_root);
n2->set_parent(new_root);
n1->update_parent(n1);
n2->update_parent(n2);
m_root = new_root;
return;
}
node_pointer parent = leaf->get_parent();
parent->replace_node(leaf, n1);
parent->add_node(n2->compute_box(), n2);
// if parent is full, split and readjust
if (parent->elements() > m_max_elems_per_node)
{
node_pointer p1(new rtree_node<Box, Value>(parent->get_parent(), parent->get_level()));
node_pointer p2(new rtree_node<Box, Value>(parent->get_parent(), parent->get_level()));
split_node(parent, p1, p2);
adjust_tree(parent, p1, p2);
}
else
{
adjust_tree(parent);
}
}
/**
* \brief Splits 'n' in 'n1' and 'n2'
*/
void split_node(node_pointer const& n, node_pointer& n1, node_pointer& n2) const
{
unsigned int seed1 = 0;
unsigned int seed2 = 0;
std::vector<Box> boxes = n->get_boxes();
n1->set_parent(n->get_parent());
n2->set_parent(n->get_parent());
linear_pick_seeds(n, seed1, seed2);
if (n->is_leaf())
{
n1->add_value(boxes[seed1], n->get_value(seed1));
n2->add_value(boxes[seed2], n->get_value(seed2));
}
else
{
n1->add_node(boxes[seed1], n->get_node(seed1));
n2->add_node(boxes[seed2], n->get_node(seed2));
}
unsigned int index = 0;
if (n->is_leaf())
{
// TODO: mloskot - add assert(node.size() >= 2); or similar
typename rtree_leaf<Box, Value>::leaf_map nodes = n->get_leaves();
unsigned int remaining = nodes.size() - 2;
for (typename rtree_leaf<Box, Value>::leaf_map::const_iterator it = nodes.begin();
it != nodes.end(); ++it, index++)
{
if (index != seed1 && index != seed2)
{
if (n1->elements() + remaining == m_min_elems_per_node)
{
n1->add_value(it->first, it->second);
continue;
}
if (n2->elements() + remaining == m_min_elems_per_node)
{
n2->add_value(it->first, it->second);
continue;
}
remaining--;
/// current boxes of each group
Box b1, b2;
/// enlarged boxes of each group
Box eb1, eb2;
b1 = n1->compute_box();
b2 = n2->compute_box();
/// areas
typedef typename coordinate_type<Box>::type coordinate_type;
coordinate_type b1_area, b2_area;
coordinate_type eb1_area, eb2_area;
b1_area = geometry::area(b1);
b2_area = geometry::area(b2);
eb1_area = compute_union_area(b1, it->first);
eb2_area = compute_union_area(b2, it->first);
if (eb1_area - b1_area > eb2_area - b2_area)
{
n2->add_value(it->first, it->second);
}
if (eb1_area - b1_area < eb2_area - b2_area)
{
n1->add_value(it->first, it->second);
}
if (eb1_area - b1_area == eb2_area - b2_area)
{
if (b1_area < b2_area)
{
n1->add_value(it->first, it->second);
}
if (b1_area > b2_area)
{
n2->add_value(it->first, it->second);
}
if (b1_area == b2_area)
{
if (n1->elements() > n2->elements())
{
n2->add_value(it->first, it->second);
}
else
{
n1->add_value(it->first, it->second);
}
}
}
}
}
}
else
{
// TODO: mloskot - add assert(node.size() >= 2); or similar
typename rtree_node<Box, Value>::node_map nodes = n->get_nodes();
unsigned int remaining = nodes.size() - 2;
for(typename rtree_node<Box, Value>::node_map::const_iterator it = nodes.begin();
it != nodes.end(); ++it, index++)
{
if (index != seed1 && index != seed2)
{
if (n1->elements() + remaining == m_min_elems_per_node)
{
n1->add_node(it->first, it->second);
continue;
}
if (n2->elements() + remaining == m_min_elems_per_node)
{
n2->add_node(it->first, it->second);
continue;
}
remaining--;
/// current boxes of each group
Box b1, b2;
/// enlarged boxes of each group
Box eb1, eb2;
b1 = n1->compute_box();
b2 = n2->compute_box();
/// areas
typedef typename coordinate_type<Box>::type coordinate_type;
coordinate_type b1_area, b2_area;
coordinate_type eb1_area, eb2_area;
b1_area = geometry::area(b1);
b2_area = geometry::area(b2);
eb1_area = compute_union_area(b1, it->first);
eb2_area = compute_union_area(b2, it->first);
if (eb1_area - b1_area > eb2_area - b2_area)
{
n2->add_node(it->first, it->second);
}
if (eb1_area - b1_area < eb2_area - b2_area)
{
n1->add_node(it->first, it->second);
}
if (eb1_area - b1_area == eb2_area - b2_area)
{
if (b1_area < b2_area)
{
n1->add_node(it->first, it->second);
}
if (b1_area > b2_area)
{
n2->add_node(it->first, it->second);
}
if (b1_area == b2_area)
{
if (n1->elements() > n2->elements())
{
n2->add_node(it->first, it->second);
}
else
{
n1->add_node(it->first, it->second);
}
}
}
}
}
}
}
/**
* \brief Choose initial values for the split algorithm (linear version)
*/
void linear_pick_seeds(node_pointer const& n, unsigned int &seed1, unsigned int &seed2) const
{
// get boxes from the node
std::vector<Box>boxes = n->get_boxes();
if (boxes.size() == 0)
{
// TODO: mloskot - throw ggl exception
throw std::logic_error("Empty Node trying to Pick Seeds");
}
// only two dim for now
// unsigned int dimensions =
// geometry::point_traits<Point>::coordinate_count;
// find the first two elements
typedef typename coordinate_type<Box>::type coordinate_type;
coordinate_type separation_x, separation_y;
unsigned int first_x, second_x;
unsigned int first_y, second_y;
find_normalized_separations<0u>(boxes, separation_x, first_x, second_x);
find_normalized_separations<1u>(boxes, separation_y, first_y, second_y);
if (separation_x > separation_y)
{
seed1 = first_x;
seed2 = second_x;
}
else
{
seed1 = first_y;
seed2 = second_y;
}
}
/**
* \brief Find distances between possible initial values for the
* pick_seeds algorithm.
*/
template <std::size_t D, typename T>
void find_normalized_separations(std::vector<Box> const& boxes, T& separation,
unsigned int& first, unsigned int& second) const
{
if (boxes.size() < 2)
{
throw std::logic_error("At least two boxes needed to split");
}
// find the lowest high
typename std::vector<Box>::const_iterator it = boxes.begin();
typedef typename coordinate_type<Box>::type coordinate_type;
coordinate_type lowest_high = geometry::get<max_corner, D>(*it);
unsigned int lowest_high_index = 0;
unsigned int index = 1;
++it;
for(; it != boxes.end(); ++it)
{
if (geometry::get<max_corner, D>(*it) < lowest_high)
{
lowest_high = geometry::get<max_corner, D>(*it);
lowest_high_index = index;
}
index++;
}
// find the highest low
coordinate_type highest_low = 0;
unsigned int highest_low_index = 0;
if (lowest_high_index == 0)
{
highest_low = geometry::get<min_corner, D>(boxes[1]);
highest_low_index = 1;
}
else
{
highest_low = geometry::get<min_corner, D>(boxes[0]);
highest_low_index = 0;
}
index = 0;
for (it = boxes.begin();
it != boxes.end(); ++it, index++)
{
if (geometry::get<min_corner, D>(*it) >= highest_low && index != lowest_high_index)
{
highest_low = geometry::get<min_corner, D>(*it);
highest_low_index = index;
}
}
// find the lowest low
it = boxes.begin();
coordinate_type lowest_low = geometry::get<min_corner, D>(*it);
++it;
for(; it != boxes.end(); ++it)
{
if (geometry::get<min_corner, D>(*it) < lowest_low)
{
lowest_low = geometry::get<min_corner, D>(*it);
}
}
// find the highest high
it = boxes.begin();
coordinate_type highest_high = geometry::get<max_corner, D>(*it);
++it;
for(; it != boxes.end(); ++it)
{
if (geometry::get<max_corner, D>(*it) > highest_high)
{
highest_high = geometry::get<max_corner, D>(*it);
}
}
coordinate_type const width = highest_high - lowest_low;
separation = (highest_low - lowest_high) / width;
first = highest_low_index;
second = lowest_high_index;
}
/**
* \brief Choose one of the possible leaves to make an insertion
*/
inline node_pointer choose_corresponding_leaf(Box const& e)
{
node_pointer node = m_root;
// if the tree is empty add an initial leaf
if (m_root->elements() == 0)
{
leaf_pointer new_leaf(new rtree_leaf<Box, Value>(m_root));
m_root->add_leaf_node(Box (), new_leaf);
return new_leaf;
}
while (!node->is_leaf())
{
/// traverse node's map to see which node we should select
node = node->choose_node(e);
}
return node;
}
/**
* \brief Choose the exact leaf where an insertion should be done
*/
node_pointer choose_exact_leaf(Box const&e) const
{
// find possible leaves
typedef typename std::vector<node_pointer> node_type;
node_type nodes;
m_root->find_leaves(e, nodes);
// refine the result
for (typename node_type::const_iterator it = nodes.begin(); it != nodes.end(); ++it)
{
typedef std::vector<std::pair<Box, Value> > leaves_type;
leaves_type leaves = (*it)->get_leaves();
for (typename leaves_type::const_iterator itl = leaves.begin();
itl != leaves.end(); ++itl)
{
if (itl->first.max_corner() == e.max_corner()
&& itl->first.min_corner() == e.min_corner())
{
return *it;
}
}
}
// TODO: mloskot - ggl exception
throw std::logic_error("Leaf not found");
}
};
}}} // namespace boost::geometry::index
#endif // BOOST_GEOMETRY_EXTENSIONS_INDEX_RTREE_RTREE_HPP