ANN-Sample

#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <fstream>
#include <ANN/ANN.h>

using namespace std;
void getArgs(int argc, char **argv);
int k = 1;
int dim = 2;
double eps = 0;
int maxPts = 1000;

istream* dataIn = NULL;
istream* queryIn = NULL;

bool readPt(istream &in, ANNpoint p)
{
 for (int i = 0; i < dim; i++) {
 if(!(in >> p[i])) return false;
 }
 return true;
}

void printPt(ostream &out, ANNpoint p)
{
 out << "(" << p[0];
 for (int i = 1; i < dim; i++) {
 out << ", " << p[i];
 }
 out << ")\n";
}

int main(int argc, char **argv)
{
 int nPts;
 ANNpointArray dataPts;
 ANNpoint queryPt;
 ANNidxArray nnIdx;
 ANNdistArray dists;
 ANNkd_tree* kdTree;

 getArgs(argc, argv);

 queryPt = annAllocPt(dim);
 dataPts = annAllocPts(maxPts, dim);
 nnIdx = new ANNidx[k];
 dists = new ANNdist[k];

 nPts = 0;

 cout << "Data Points:\n";
 while (nPts < maxPts && readPt(*dataIn, dataPts[nPts])) {
 printPt(cout, dataPts[nPts]);
 nPts++;
 }

 kdTree = new ANNkd_tree(
 dataPts,
 nPts,
 dim);

 while (readPt(*queryIn, queryPt)) {
 cout << "Query point: ";
 printPt(cout, queryPt);

 kdTree->annkSearch(
 queryPt,
 k,
 nnIdx,
 dists,
 eps);

 cout << "\tNN:\tIndex\tDistance\n";
 for (int i = 0; i < k; i++) {
 dists[i] = sqrt(dists[i]);
 cout << "\t" << i << "\t" << nnIdx[i] << "\t" << dists[i] << "\n";
 }
 }
 delete [] nnIdx;
 delete [] dists;
 delete kdTree;
 annClose();

 return EXIT_SUCCESS;
}void getArgs(int argc, char **argv)
{
 static ifstream dataStream;
 static ifstream queryStream;

 if (argc <= 1) {
 cerr << "Usage:\n\n"
 << " ann_sample [-d dim] [-max m] [-nn k] [-e eps] [-df data]"
 " [-qf query]\n\n"
 << " where:\n"
 << " dim dimension of the space (default = 2)\n"
 << " m maximum number of data points (default = 1000)\n"
 << " k number of nearest neighbors per query (default 1)\n"
 << " eps the error bound (default = 0.0)\n"
 << " data name of file containing data points\n"
 << " query name of file containing query points\n\n"
 << " Results are sent to the standard output.\n"
 << "\n"
 << " To run this demo use:\n"
 << " ann_sample -df data.pts -qf query.pts\n";
 exit(0);
 }
 int i = 1;
 while (i < argc) {
 if (!strcmp(argv[i], "-d")) {
 dim = atoi(argv[++i]);
 }
 else if (!strcmp(argv[i], "-max")) {
 maxPts = atoi(argv[++i]);
 }
 else if (!strcmp(argv[i], "-nn")) {
 k = atoi(argv[++i]);
 }
 else if (!strcmp(argv[i], "-e")) {
 sscanf(argv[++i], "%lf", &eps);
 }
 else if (!strcmp(argv[i], "-df")) {
 dataStream.open(argv[++i], ios::in);
 if (!dataStream) {
 cerr << "Cannot open data file\n";
 exit(1);
 }
 dataIn = &dataStream;
 }
 else if (!strcmp(argv[i], "-qf")) {
 queryStream.open(argv[++i], ios::in);
 if (!queryStream) {
 cerr << "Cannot open query file\n";
 exit(1);
 }
 queryIn = &queryStream;
 }
 else {
 cerr << "Unrecognized option.\n";
 exit(1);
 }
 i++;
 }
 if (dataIn == NULL || queryIn == NULL) {
 cerr << "-df and -qf options must be specified\n";
 exit(1);
 }
}