标签:output The 随机 filter ons res omsa sig resize
#include <stdio.h> #include <stdlib.h> #include <time.h> #include <iostream> #include <vector> float unifRand() { return (static_cast<float>(rand() / double(RAND_MAX))); //return (((214013 * seed_ + 2531011) >> 16) & 0x7FFF); } int randomSample(std::vector<int>&indices_, unsigned int& N, const unsigned int& sample_size, std::vector<int>&indices) { //unsigned N = static_cast<unsigned> (30); //max //unsigned int sample_size = 20; //std::vector<int>indices; //std::vector<int>indices_(N); for (size_t i = 0; i < N; i++) { indices_[i] = i; } // If sample size is 0 or if the sample size is greater then input cloud size // then return all indices if (sample_size >= N) { printf("sample_size >= N ......");// } else { // Resize output indices to sample size indices.resize(static_cast<size_t> (sample_size)); // Set random seed so derived indices are the same each time the filter runs std::srand(static_cast<unsigned int>(time(NULL))); // Algorithm A unsigned top = N - sample_size; unsigned i = 0; unsigned index = 0; for (size_t n = sample_size; n >= 2; n--) { float V = unifRand(); unsigned S = 0; float quot = static_cast<float> (top) / static_cast<float> (N); while (quot > V) { S++; top--; N--; quot = quot * static_cast<float> (top) / static_cast<float> (N); } index += S; indices[i++] = indices_[index++]; N--; } } return 0; } int main(int argc, char** argv) { /*****************方法一****************/ //方法一 会产生重复数字 /* int n = 30; double U; int random_num; srand(static_cast<unsigned int>(time(NULL))); //初始化随机数种子 for (int i = 0; i < 20; i++) { U = (double)rand() / RAND_MAX; //生成[0,1]之间的随机数 random_num = (int)((n - 1)*U + 0.5); //生成[0,n-1]之间的随机数 printf("%d ", random_num); }*/ /*****************方法二****************/ unsigned int N = static_cast<unsigned int> (30); //max unsigned int sample_size = 20; std::vector<int>indices; std::vector<int>indices_(N); randomSample(indices_, N, sample_size, indices); return 0; }
标签:output The 随机 filter ons res omsa sig resize
原文地址:https://www.cnblogs.com/lovebay/p/12378358.html