- kdtree的原理就是基于二叉树的形式,将高维空间用超矩形进行划分.其主要用途是用来求解高维空间中最近邻的值.
下面是kdtree.h文件,是kdtree数据结构的头文件
- #ifndef _KDTREE_H_
- #define _KDTREE_H_
-
- #ifdef __cplusplus
- extern "C" {
- #endif
-
- struct kdtree;
- struct kdres;
-
-
- /* create a kd-tree for "k"-dimensional data */
- struct kdtree *kd_create(int k);
-
- /* free the struct kdtree */
- void kd_free(struct kdtree *tree);
-
- /* remove all the elements from the tree */
- void kd_clear(struct kdtree *tree);
-
- /* if called with non-null 2nd argument, the function provided
- * will be called on data pointers (see kd_insert) when nodes
- * are to be removed from the tree.
- */
- void kd_data_destructor(struct kdtree *tree, void (*destr)(void*));
-
- /* insert a node, specifying its position, and optional data */
- int kd_insert(struct kdtree *tree, const double *pos, void *data);
- int kd_insertf(struct kdtree *tree, const float *pos, void *data);
- int kd_insert3(struct kdtree *tree, double x, double y, double z, void *data);
- int kd_insert3f(struct kdtree *tree, float x, float y, float z, void *data);
-
- /* Find the nearest node from a given point.
- *
- * This function returns a pointer to a result set with at most one element.
- */
- struct kdres *kd_nearest(struct kdtree *tree, const double *pos);
- struct kdres *kd_nearestf(struct kdtree *tree, const float *pos);
- struct kdres *kd_nearest3(struct kdtree *tree, double x, double y, double z);
- struct kdres *kd_nearest3f(struct kdtree *tree, float x, float y, float z);
-
- /* Find the N nearest nodes from a given point.
- *
- * This function returns a pointer to a result set, with at most N elements,
- * which can be manipulated with the kd_res_* functions.
- * The returned pointer can be null as an indication of an error. Otherwise
- * a valid result set is always returned which may contain 0 or more elements.
- * The result set must be deallocated with kd_res_free after use.
- */
- /*
- struct kdres *kd_nearest_n(struct kdtree *tree, const double *pos, int num);
- struct kdres *kd_nearest_nf(struct kdtree *tree, const float *pos, int num);
- struct kdres *kd_nearest_n3(struct kdtree *tree, double x, double y, double z);
- struct kdres *kd_nearest_n3f(struct kdtree *tree, float x, float y, float z);
- */
-
- /* Find any nearest nodes from a given point within a range.
- *
- * This function returns a pointer to a result set, which can be manipulated
- * by the kd_res_* functions.
- * The returned pointer can be null as an indication of an error. Otherwise
- * a valid result set is always returned which may contain 0 or more elements.
- * The result set must be deallocated with kd_res_free after use.
- */
- struct kdres *kd_nearest_range(struct kdtree *tree, const double *pos, double range);
- struct kdres *kd_nearest_rangef(struct kdtree *tree, const float *pos, float range);
- struct kdres *kd_nearest_range3(struct kdtree *tree, double x, double y, double z, double range);
- struct kdres *kd_nearest_range3f(struct kdtree *tree, float x, float y, float z, float range);
-
- /* frees a result set returned by kd_nearest_range() */
- void kd_res_free(struct kdres *set);
-
- /* returns the size of the result set (in elements) */
- int kd_res_size(struct kdres *set);
-
- /* rewinds the result set iterator */
- void kd_res_rewind(struct kdres *set);
-
- /* returns non-zero if the set iterator reached the end after the last element */
- int kd_res_end(struct kdres *set);
-
- /* advances the result set iterator, returns non-zero on success, zero if
- * there are no more elements in the result set.
- */
- int kd_res_next(struct kdres *set);
-
- /* returns the data pointer (can be null) of the current result set item
- * and optionally sets its position to the pointers(s) if not null.
- */
- void *kd_res_item(struct kdres *set, double *pos);
- void *kd_res_itemf(struct kdres *set, float *pos);
- void *kd_res_item3(struct kdres *set, double *x, double *y, double *z);
- void *kd_res_item3f(struct kdres *set, float *x, float *y, float *z);
-
- /* equivalent to kd_res_item(set, 0) */
- void *kd_res_item_data(struct kdres *set);
-
-
- #ifdef __cplusplus
- }
- #endif
-
- #endif /* _KDTREE_H_ */
下面是kdtree.c 文件,上面有我自己精心整理的详细的汉语注释,这个版本的kdtree可直接拿来用
- //kd_tree.h kd_tree的头文件
-
- #include "stdafx.h"
-
- //头文件
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <math.h>
- #include "kd_tree.h"
-
- #if defined(WIN32) || defined(__WIN32__)
- #include <malloc.h>
- #endif
-
- #ifdef USE_LIST_NODE_ALLOCATOR
-
- #ifndef NO_PTHREADS
- #include <pthread.h>
- #else
-
- #ifndef I_WANT_THREAD_BUGS
- #error "You are compiling with the fast list node allocator, with pthreads disabled! This WILL break if used from multiple threads."
- #endif /* I want thread bugs */
-
- #endif /* pthread support */
- #endif /* use list node allocator */
-
-
- //超平面的结构体
- //包括一个属性的维数和每维坐标的最大和最小值构成的数组
- struct kdhyperrect {
- int dim;
- double *min, *max; /* minimum/maximum coords */
- };
-
- //节点的结构体,也就是事例的结构体
- struct kdnode {
- double *pos;
- int dir;
- void *data;
-
- struct kdnode *left, *right; /* negative/positive side */
- };
-
- //返回结果节点, 包括树的节点,距离值, 是一个单链表的形式
- struct res_node {
- struct kdnode *item;
- double dist_sq;
- struct res_node *next;
- };
-
- //树有几个属性,一是维数,一是树根节点,一是超平面,一是销毁data的函数
- struct kdtree {
- int dim;
- struct kdnode *root;
- struct kdhyperrect *rect;
- void (*destr)(void*);
- };
-
- //kdtree的返回结果,包括kdtree,这是一个双链表的形式
- struct kdres {
- struct kdtree *tree;
- struct res_node *rlist, *riter; //双链表?
- int size;
- };
-
- //计算平方的宏定义,相当于函数
- #define SQ(x) ((x) * (x))
-
-
- static void clear_rec(struct kdnode *node, void (*destr)(void*));
- static int insert_rec(struct kdnode **node, const double *pos, void *data, int dir, int dim);
- static int rlist_insert(struct res_node *list, struct kdnode *item, double dist_sq);
- static void clear_results(struct kdres *set);
-
- static struct kdhyperrect* hyperrect_create(int dim, const double *min, const double *max);
- static void hyperrect_free(struct kdhyperrect *rect);
- static struct kdhyperrect* hyperrect_duplicate(const struct kdhyperrect *rect);
- static void hyperrect_extend(struct kdhyperrect *rect, const double *pos);
- static double hyperrect_dist_sq(struct kdhyperrect *rect, const double *pos);
-
- #ifdef USE_LIST_NODE_ALLOCATOR
- static struct res_node *alloc_resnode(void);
- static void free_resnode(struct res_node*);
- #else
- #define alloc_resnode() malloc(sizeof(struct res_node))
- #define free_resnode(n) free(n)
- #endif
-
-
- //创建一个kdtree
- struct kdtree *kd_create(int k)
- {
- struct kdtree *tree;
-
- if(!(tree = (kdtree*)malloc(sizeof *tree))) {
- return 0;
- }
-
- tree->dim = k;
- tree->root = 0;
- tree->destr = 0;
- tree->rect = 0;
-
- return tree;
- }
-
- //释放掉kdtree
- void kd_free(struct kdtree *tree)
- {
- if(tree) {
- kd_clear(tree);
- free(tree);
- }
- }
-
- //清除掉超平面,是按节点递归地进行的
- static void clear_rec(struct kdnode *node, void (*destr)(void*))
- {
- if(!node) return; //一个节点对应一个超平面
-
- //递归函数,递归地清除掉二叉树左分支的超平面和二叉树右分支的超平面
- clear_rec(node->left, destr);
- clear_rec(node->right, destr);
-
- //如果data清楚函数不为空,就释放掉data
- if(destr)
- {
- destr(node->data);
- }
- //释放节点的坐标数组
- free(node->pos);
- //释放节点
- free(node);
- }
-
- //kdtree清除
- void kd_clear(struct kdtree *tree)
- {
- //清除树中每个节点的超平面,释放树中的各个节点
- clear_rec(tree->root, tree->destr);
- tree->root = 0;
-
- //如果树的超平面指针不为空,对其进行释放
- if (tree->rect)
- {
- hyperrect_free(tree->rect);
- tree->rect = 0;
- }
- }
-
- //数据销毁,用一个外来的函数来进行data的销毁
- void kd_data_destructor(struct kdtree *tree, void (*destr)(void*))
- {
- //用外来的函数来执行kdtree的销毁函数
- tree->destr = destr;
- }
-
-
- //在一个树节点位置处插入超矩形
- static int insert_rec(struct kdnode **nptr, const double *pos, void *data, int dir, int dim)
- {
- int new_dir;
- struct kdnode *node;
-
- //如果这个节点是不存在的
- if(!*nptr)
- {
- //分配一个结点
- if(!(node = (kdnode *)malloc(sizeof *node)))
- {
- return -1;
- }
- if(!(node->pos = (double*)malloc(dim * sizeof *node->pos))) {
- free(node);
- return -1;
- }
- memcpy(node->pos, pos, dim * sizeof *node->pos);
- node->data = data;
- node->dir = dir;
- node->left = node->right = 0;
- *nptr = node;
- return 0;
- }
-
- node = *nptr;
- new_dir = (node->dir + 1) % dim;
- if(pos[node->dir] < node->pos[node->dir]) {
- return insert_rec(&(*nptr)->left, pos, data, new_dir, dim);
- }
- return insert_rec(&(*nptr)->right, pos, data, new_dir, dim);
- }
-
- //节点插入操作
- //参数为:要进行插入操作的kdtree,要插入的节点坐标,要插入的节点的数据
- int kd_insert(struct kdtree *tree, const double *pos, void *data)
- {
- //插入超矩形
- if (insert_rec(&tree->root, pos, data, 0, tree->dim))
- {
- return -1;
- }
- //如果树还没有超矩形,就创建一个超矩形
- //如果已经有了超矩形,就扩展原有的超矩形
- if (tree->rect == 0)
- {
- tree->rect = hyperrect_create(tree->dim, pos, pos);
- }
- else
- {
- hyperrect_extend(tree->rect, pos);
- }
-
- return 0;
- }
-
- //插入float型坐标的节点
- //参数为:要进行插入操作的kdtree,要插入的节点坐标,要插入的节点的数据
- //将float型的坐标赋值给double型的缓冲区,经过这个类型转化后进行插入
- //本质上是一种类型转化
- int kd_insertf(struct kdtree *tree, const float *pos, void *data)
- {
- static double sbuf[16];
- double *bptr, *buf = 0;
- int res, dim = tree->dim;
-
- //如果kdtree的维数大于16, 分配dim维double类型的数组
- if(dim > 16)
- {
- #ifndef NO_ALLOCA
- if(dim <= 256)
- bptr = buf = (double*)alloca(dim * sizeof *bptr);
- else
- #endif
- if(!(bptr = buf = (double*)malloc(dim * sizeof *bptr)))
- {
- return -1;
- }
- }
- //如果kdtree的维数小于16, 直接将指针指向已分配的内存
- else
- {
- bptr = buf = sbuf;
- }
-
- //将要插入点的位置坐标赋值给分配的数组
- while(dim-- > 0)
- {
- *bptr++ = *pos++;
- }
-
- //调用节点插入函数kd_insert
- res = kd_insert(tree, buf, data);
- #ifndef NO_ALLOCA
- if(tree->dim > 256)
- #else
- if(tree->dim > 16)
- #endif
- //释放缓存
- free(buf);
- return res;
- }
-
- //给出三维坐标值的三维kdtree插入
- int kd_insert3(struct kdtree *tree, double x, double y, double z, void *data)
- {
- double buf[3];
- buf[0] = x;
- buf[1] = y;
- buf[2] = z;
- return kd_insert(tree, buf, data);
- }
-
- //给出三维float型坐标值的三维kdtree插入
- int kd_insert3f(struct kdtree *tree, float x, float y, float z, void *data)
- {
- double buf[3];
- buf[0] = x;
- buf[1] = y;
- buf[2] = z;
- return kd_insert(tree, buf, data);
- }
-
- //找到最近邻的点
- //参数为:树节点指针, 位置坐标, 阈值, 返回结果的节点, bool型排序,维度
- static int find_nearest(struct kdnode *node, const double *pos, double range, struct res_node *list, int ordered, int dim)
- {
- double dist_sq, dx;
- int i, ret, added_res = 0;
-
- if(!node) return 0; //注意这个地方,当节点为空的时候,表明已经查找到最终的叶子结点,返回值为零
-
- dist_sq = 0;
- //计算两个节点间的平方和
- for(i=0; i<dim; i++)
- {
- dist_sq += SQ(node->pos[i] - pos[i]);
- }
- //如果距离在阈值范围内,就将其插入到返回结果链表中
- if(dist_sq <= SQ(range))
- {
- if(rlist_insert(list, node, ordered ? dist_sq : -1.0) == -1)
- {
- return -1;
- }
- added_res = 1;
- }
-
- //在这个节点的划分方向上,求两者之间的差值
- dx = pos[node->dir] - node->pos[node->dir];
-
- //根据这个差值的符号, 选择进行递归查找的分支方向
- ret = find_nearest(dx <= 0.0 ? node->left : node->right, pos, range, list, ordered, dim);
- //如果返回的值大于等于零,表明在这个分支中有满足条件的节点,则返回结果的个数进行累加,并在节点的另一个方向进行查找最近的节点
- if(ret >= 0 && fabs(dx) < range)
- {
- added_res += ret;
- ret = find_nearest(dx <= 0.0 ? node->right : node->left, pos, range, list, ordered, dim);
- }
- if(ret == -1)
- {
- return -1;
- }
- added_res += ret;
-
- return added_res;
- }
-
-
- //找到最近邻的n个节点
- #if 0
- static int find_nearest_n(struct kdnode *node, const double *pos, double range, int num, struct rheap *heap, int dim)
- {
- double dist_sq, dx;
- int i, ret, added_res = 0;
-
- if(!node) return 0;
-
- /* if the photon is close enough, add it to the result heap */
- //如果足够近就将其加入到结果堆中
- dist_sq = 0;
- //计算两者间的欧式距离
- for(i=0; i<dim; i++)
- {
- dist_sq += SQ(node->pos[i] - pos[i]);
- }
- //如果计算所得距离小于阈值
- if(dist_sq <= range_sq) {
- //如果堆的大小大于num,也就是大于总的要找的节点数
- if(heap->size >= num)
- {
- /* get furthest element */
- //得到最远的节点
- struct res_node *maxelem = rheap_get_max(heap);
-
- /* and check if the new one is closer than that */
- //测试这个节点是不是比最远的节点要近
- if(maxelem->dist_sq > dist_sq)
- {
- //如果是的话,就移除最远的节点
- rheap_remove_max(heap);
- //并将此节点插入堆中
- if(rheap_insert(heap, node, dist_sq) == -1)
- {
- return -1;
- }
- added_res = 1;
-
- range_sq = dist_sq;
- }
- }
- //如果堆的大小小于num,直接将此节点插入堆中
- else
- {
- if(rheap_insert(heap, node, dist_sq) == -1)
- {
- return =1;
- }
- added_res = 1;
- }
- }
-
-
- /* find signed distance from the splitting plane */
- dx = pos[node->dir] - node->pos[node->dir];
-
- ret = find_nearest_n(dx <= 0.0 ? node->left : node->right, pos, range, num, heap, dim);
- if(ret >= 0 && fabs(dx) < range) {
- added_res += ret;
- ret = find_nearest_n(dx <= 0.0 ? node->right : node->left, pos, range, num, heap, dim);
- }
- }
- #endif
-
-
- static void kd_nearest_i(struct kdnode *node, const double *pos, struct kdnode **result, double *result_dist_sq, struct kdhyperrect* rect)
- {
- int dir = node->dir;
- int i;
- double dummy, dist_sq;
- struct kdnode *nearer_subtree, *farther_subtree;
- double *nearer_hyperrect_coord, *farther_hyperrect_coord;
-
- /* Decide whether to go left or right in the tree */
- //在二叉树中,决定向左走还是向右走
- dummy = pos[dir] - node->pos[dir];
- if (dummy <= 0)
- {
- nearer_subtree = node->left;
- farther_subtree = node->right;
- nearer_hyperrect_coord = rect->max + dir;
- farther_hyperrect_coord = rect->min + dir;
- }
- else
- {
- nearer_subtree = node->right;
- farther_subtree = node->left;
- nearer_hyperrect_coord = rect->min + dir;
- farther_hyperrect_coord = rect->max + dir;
- }
-
- if (nearer_subtree) {
- /* Slice the hyperrect to get the hyperrect of the nearer subtree */
- dummy = *nearer_hyperrect_coord;
- *nearer_hyperrect_coord = node->pos[dir];
- /* Recurse down into nearer subtree */
- kd_nearest_i(nearer_subtree, pos, result, result_dist_sq, rect);
- /* Undo the slice */
- *nearer_hyperrect_coord = dummy;
- }
-
- /* Check the distance of the point at the current node, compare it
- * with our best so far */
- dist_sq = 0;
- for(i=0; i < rect->dim; i++)
- {
- dist_sq += SQ(node->pos[i] - pos[i]);
- }
- if (dist_sq < *result_dist_sq)
- {
- *result = node;
- *result_dist_sq = dist_sq;
- }
-
- if (farther_subtree) {
- /* Get the hyperrect of the farther subtree */
- dummy = *farther_hyperrect_coord;
- *farther_hyperrect_coord = node->pos[dir];
- /* Check if we have to recurse down by calculating the closest
- * point of the hyperrect and see if it's closer than our
- * minimum distance in result_dist_sq. */
- if (hyperrect_dist_sq(rect, pos) < *result_dist_sq) {
- /* Recurse down into farther subtree */
- kd_nearest_i(farther_subtree, pos, result, result_dist_sq, rect);
- }
- /* Undo the slice on the hyperrect */
- *farther_hyperrect_coord = dummy;
- }
- }
-
- //求kdtree中与点pos最近邻的值
- struct kdres *kd_nearest(struct kdtree *kd, const double *pos)
- {
- struct kdhyperrect *rect;
- struct kdnode *result;
- struct kdres *rset;
- double dist_sq;
- int i;
-
- //如果kd不存在,或者其超平面不存在的话,则就不会有结果
- if (!kd) return 0;
- if (!kd->rect) return 0;
-
- /* Allocate result set */
- //为返回结果集合分配空间
- if(!(rset = (kdres*)malloc(sizeof *rset)))
- {
- return 0;
- }
- if(!(rset->rlist = (res_node*)alloc_resnode())) {
- free(rset);
- return 0;
- }
- rset->rlist->next = 0;
- rset->tree = kd;
-
- /* Duplicate the bounding hyperrectangle, we will work on the copy */
- //复制边界超平面
- if (!(rect = hyperrect_duplicate(kd->rect)))
- {
- kd_res_free(rset);
- return 0;
- }
-
- /* Our first guesstimate is the root node */
- result = kd->root;
- dist_sq = 0;
- for (i = 0; i < kd->dim; i++)
- dist_sq += SQ(result->pos[i] - pos[i]);
-
- /* Search for the nearest neighbour recursively */
- //递归地查找最近邻的邻居
- kd_nearest_i(kd->root, pos, &result, &dist_sq, rect);
-
- /* Free the copy of the hyperrect */
- //释放超矩形
- hyperrect_free(rect);
-
- /* Store the result */
- //存储结果
- if (result)
- {
- if (rlist_insert(rset->rlist, result, -1.0) == -1)
- {
- kd_res_free(rset);
- return 0;
- }
- rset->size = 1;
- kd_res_rewind(rset);
- return rset;
- }
- else
- {
- kd_res_free(rset);
- return 0;
- }
- }
-
- //kd_nearest的float特例
- struct kdres *kd_nearestf(struct kdtree *tree, const float *pos)
- {
- static double sbuf[16];
- double *bptr, *buf = 0;
- int dim = tree->dim;
- struct kdres *res;
-
- if(dim > 16) {
- #ifndef NO_ALLOCA
- if(dim <= 256)
- bptr = buf = (double*)alloca(dim * sizeof *bptr);
- else
- #endif
- if(!(bptr = buf = (double*)malloc(dim * sizeof *bptr))) {
- return 0;
- }
- } else {
- bptr = buf = sbuf;
- }
-
- while(dim-- > 0) {
- *bptr++ = *pos++;
- }
-
- res = kd_nearest(tree, buf);
- #ifndef NO_ALLOCA
- if(tree->dim > 256)
- #else
- if(tree->dim > 16)
- #endif
- free(buf);
- return res;
- }
-
- //kd_nearest的三坐标特例
- struct kdres *kd_nearest3(struct kdtree *tree, double x, double y, double z)
- {
- double pos[3];
- pos[0] = x;
- pos[1] = y;
- pos[2] = z;
- return kd_nearest(tree, pos);
- }
-
- //kd_nearest的三坐标float特例
- struct kdres *kd_nearest3f(struct kdtree *tree, float x, float y, float z)
- {
- double pos[3];
- pos[0] = x;
- pos[1] = y;
- pos[2] = z;
- return kd_nearest(tree, pos);
- }
-
- /* ---- nearest N search ---- */
- /*
- static kdres *kd_nearest_n(struct kdtree *kd, const double *pos, int num)
- {
- int ret;
- struct kdres *rset;
-
- if(!(rset = malloc(sizeof *rset))) {
- return 0;
- }
- if(!(rset->rlist = alloc_resnode())) {
- free(rset);
- return 0;
- }
- rset->rlist->next = 0;
- rset->tree = kd;
-
- if((ret = find_nearest_n(kd->root, pos, range, num, rset->rlist, kd->dim)) == -1) {
- kd_res_free(rset);
- return 0;
- }
- rset->size = ret;
- kd_res_rewind(rset);
- return rset;
- }*/
-
- //找到满足距离小于range值的节点
- struct kdres *kd_nearest_range(struct kdtree *kd, const double *pos, double range)
- {
- int ret;
- struct kdres *rset;
-
- if(!(rset = (kdres*)malloc(sizeof *rset))) {
- return 0;
- }
- if(!(rset->rlist = (res_node*)alloc_resnode())) {
- free(rset);
- return 0;
- }
- rset->rlist->next = 0;
- rset->tree = kd;
-
- if((ret = find_nearest(kd->root, pos, range, rset->rlist, 0, kd->dim)) == -1) {
- kd_res_free(rset);
- return 0;
- }
- rset->size = ret;
- kd_res_rewind(rset);
- return rset;
- }
-
- //kd_nearest_range的float特例
- struct kdres *kd_nearest_rangef(struct kdtree *kd, const float *pos, float range)
- {
- static double sbuf[16];
- double *bptr, *buf = 0;
- int dim = kd->dim;
- struct kdres *res;
-
- if(dim > 16) {
- #ifndef NO_ALLOCA
- if(dim <= 256)
- bptr = buf = (double*)alloca(dim * sizeof *bptr);
- else
- #endif
- if(!(bptr = buf = (double*)malloc(dim * sizeof *bptr))) {
- return 0;
- }
- } else {
- bptr = buf = sbuf;
- }
-
- while(dim-- > 0) {
- *bptr++ = *pos++;
- }
-
- res = kd_nearest_range(kd, buf, range);
- #ifndef NO_ALLOCA
- if(kd->dim > 256)
- #else
- if(kd->dim > 16)
- #endif
- free(buf);
- return res;
- }
-
- //kd_nearest_range的三坐标特例
- struct kdres *kd_nearest_range3(struct kdtree *tree, double x, double y, double z, double range)
- {
- double buf[3];
- buf[0] = x;
- buf[1] = y;
- buf[2] = z;
- return kd_nearest_range(tree, buf, range);
- }
-
- //kd_nearest_range的三坐标float特例
- struct kdres *kd_nearest_range3f(struct kdtree *tree, float x, float y, float z, float range)
- {
- double buf[3];
- buf[0] = x;
- buf[1] = y;
- buf[2] = z;
- return kd_nearest_range(tree, buf, range);
- }
-
- //返回结果的释放
- void kd_res_free(struct kdres *rset)
- {
- clear_results(rset);
- free_resnode(rset->rlist);
- free(rset);
- }
-
- //获取返回结果集合的大小
- int kd_res_size(struct kdres *set)
- {
- return (set->size);
- }
-
- //再次回到这个节点本身的位置
- void kd_res_rewind(struct kdres *rset)
- {
- rset->riter = rset->rlist->next;
- }
-
- //找到返回结果中的最终节点
- int kd_res_end(struct kdres *rset)
- {
- return rset->riter == 0;
- }
-
- //返回结果列表中的下一个节点
- int kd_res_next(struct kdres *rset)
- {
- rset->riter = rset->riter->next;
- return rset->riter != 0;
- }
-
- //将返回结果的节点的坐标和data抽取出来
- void *kd_res_item(struct kdres *rset, double *pos)
- {
- if(rset->riter) {
- if(pos) {
- memcpy(pos, rset->riter->item->pos, rset->tree->dim * sizeof *pos);
- }
- return rset->riter->item->data;
- }
- return 0;
- }
-
- //将返回结果的节点的坐标和data抽取出来,坐标为float型的值
- void *kd_res_itemf(struct kdres *rset, float *pos)
- {
- if(rset->riter) {
- if(pos) {
- int i;
- for(i=0; i<rset->tree->dim; i++) {
- pos[i] = rset->riter->item->pos[i];
- }
- }
- return rset->riter->item->data;
- }
- return 0;
- }
-
- //将返回结果的节点的坐标和data抽取出来,坐标具体形式给出
- void *kd_res_item3(struct kdres *rset, double *x, double *y, double *z)
- {
- if(rset->riter) {
- if(*x) *x = rset->riter->item->pos[0];
- if(*y) *y = rset->riter->item->pos[1];
- if(*z) *z = rset->riter->item->pos[2];
- }
- return 0;
- }
-
- //将返回结果的节点的坐标和data抽取出来,坐标为float型的值,坐标具体形式给出
- void *kd_res_item3f(struct kdres *rset, float *x, float *y, float *z)
- {
- if(rset->riter) {
- if(*x) *x = rset->riter->item->pos[0];
- if(*y) *y = rset->riter->item->pos[1];
- if(*z) *z = rset->riter->item->pos[2];
- }
- return 0;
- }
-
- //获取data数据
- void *kd_res_item_data(struct kdres *set)
- {
- return kd_res_item(set, 0);
- }
-
- /* ---- hyperrectangle helpers ---- */
- //创建超平面,包括三个参数:维度,每维的最小值和最大值数组
- static struct kdhyperrect* hyperrect_create(int dim, const double *min, const double *max)
- {
- size_t size = dim * sizeof(double);
- struct kdhyperrect* rect = 0;
-
- if (!(rect = (kdhyperrect*)malloc(sizeof(struct kdhyperrect))))
- {
- return 0;
- }
-
- rect->dim = dim;
- if (!(rect->min = (double*)malloc(size))) {
- free(rect);
- return 0;
- }
- if (!(rect->max = (double*)malloc(size))) {
- free(rect->min);
- free(rect);
- return 0;
- }
- memcpy(rect->min, min, size);
- memcpy(rect->max, max, size);
-
- return rect;
- }
-
- //释放超平面结构体
- static void hyperrect_free(struct kdhyperrect *rect)
- {
- free(rect->min);
- free(rect->max);
- free(rect);
- }
-
- //赋值超平面结构体
- static struct kdhyperrect* hyperrect_duplicate(const struct kdhyperrect *rect)
- {
- return hyperrect_create(rect->dim, rect->min, rect->max);
- }
-
- //更新超平面结构体最大\最小值数组
- static void hyperrect_extend(struct kdhyperrect *rect, const double *pos)
- {
- int i;
-
- for (i=0; i < rect->dim; i++) {
- if (pos[i] < rect->min[i]) {
- rect->min[i] = pos[i];
- }
- if (pos[i] > rect->max[i]) {
- rect->max[i] = pos[i];
- }
- }
- }
-
- //计算固定坐标点与超平面之间的距离
- static double hyperrect_dist_sq(struct kdhyperrect *rect, const double *pos)
- {
- int i;
- double result = 0;
-
- for (i=0; i < rect->dim; i++)
- {
- if (pos[i] < rect->min[i])
- {
- result += SQ(rect->min[i] - pos[i]);
- }
- else if (pos[i] > rect->max[i])
- {
- result += SQ(rect->max[i] - pos[i]);
- }
- }
- return result;
- }
-
-
- /* ---- static helpers ---- */
- #ifdef USE_LIST_NODE_ALLOCATOR
- /* special list node allocators. */
- static struct res_node *free_nodes;
-
- #ifndef NO_PTHREADS
- static pthread_mutex_t alloc_mutex = PTHREAD_MUTEX_INITIALIZER;
- #endif
-
- //创建返回结果节点
- static struct res_node *alloc_resnode(void)
- {
- struct res_node *node;
-
- #ifndef NO_PTHREADS
- pthread_mutex_lock(&alloc_mutex);
- #endif
-
- if(!free_nodes) {
- node = malloc(sizeof *node);
- } else {
- node = free_nodes;
- free_nodes = free_nodes->next;
- node->next = 0;
- }
-
- #ifndef NO_PTHREADS
- pthread_mutex_unlock(&alloc_mutex);
- #endif
-
- return node;
- }
-
- //释放返回结果节点
- static void free_resnode(struct res_node *node)
- {
- #ifndef NO_PTHREADS
- pthread_mutex_lock(&alloc_mutex);
- #endif
-
- node->next = free_nodes;
- free_nodes = node;
-
- #ifndef NO_PTHREADS
- pthread_mutex_unlock(&alloc_mutex);
- #endif
- }
- #endif /* list node allocator or not */
-
-
- /* inserts the item. if dist_sq is >= 0, then do an ordered insert */
- /* TODO make the ordering code use heapsort */
- //函数参数: 返回结果节点指针,树节点指针,距离函数
- //将一个结果节点插入到返回结果的列表中
- static int rlist_insert(struct res_node *list, struct kdnode *item, double dist_sq)
- {
- struct res_node *rnode;
-
- //创建一个返回结果的节点
- if(!(rnode = (res_node*)alloc_resnode()))
- {
- return -1;
- }
- rnode->item = item; //对应的树节点
- rnode->dist_sq = dist_sq; //对应的距离值
-
- //当距离大于零的时候
- if(dist_sq >= 0.0)
- {
- while(list->next && list->next->dist_sq < dist_sq)
- {
- list = list->next;
- }
- }
- rnode->next = list->next;
- list->next = rnode;
- return 0;
- }
-
- //清除返回结果的集合
- //本质上是个双链表中单链表的清理
- static void clear_results(struct kdres *rset)
- {
- struct res_node *tmp, *node = rset->rlist->next;
-
- while(node)
- {
- tmp = node;
- node = node->next;
- free_resnode(tmp);
- }
-
- rset->rlist->next = 0;
- }
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