C++写geohash

来源：互联网发布：慧博智能策略终端mac 编辑：程序博客网时间：2024/06/05 17:22

http://www.cnblogs.com/LBSer/p/3310455.html

http://www.sxrczx.com/pages/my.oschina.net/853294317/blog/296594.html

http://community.apicloud.com/bbs/forum.php?mod=viewthread&tid=5300

受朋友委托写个查找附近人的算法，当然是不会写，不知道从何下手，于是学习了下geohash算法。看懂后开始一步步实现，当然还没有完全写完。不会之处在于：如何对已有的字符串进行前缀匹配的呢？怎么查找附近的人呢？

写了很多注释，怕自己以后看不懂。这也算是第一次体会到算法在工程中的作用。想起以前老师说算法在开发中没用！！表示汗颜、无语。

  1 #include<iostream>  2 #include<stdio.h>  3 #include<string>  4 #include<string.h>  5 #include<map>  6 #include <stdlib.h>  7 #include <stdio.h>  8 #include <winsock.h>  9 #include <mysql.h> 10 #include <cstring> 11 using namespace std; 12 map<string, string> base32; 13  14 //将纬度、经度二进制化 15 //纬度范围(-90, 90) 16 //经度范围(-180, 180) 17 //传入w,返回二进制编码 18 //max_step控制递归次数同时也是二进制编码长度 19 //注意返回的是逆序的字符串 max_step必须是5的倍数 20 string geohash_w_bin(double w,double left,double right,int step,int max_step)  21 { 22     if (step > max_step)  23     { 24         return ""; 25     } 26     double mid = (left + right)*1.0 / 2; 27  28     if (w >= left && w <= mid) { 29         return geohash_w_bin(w, left, mid,step+1,max_step)+"0";  30     } 31     if (w >= mid && w <= right) { 32         return geohash_w_bin(w, mid, right,step+1,max_step)+"1"; 33     } 34  35 } 36  37 //合并经纬度 38 //传入经度和纬度 返回合并的二进制编码 39 string geohash_merge(string j, string w) { 40     string s; 41     for (int i = 0; i <j.size(); i++){ 42         s += j[i]; 43         s += w[i]; 44     } 45     return s; 46 } 47  48 //二进制编码base32化 49 string geohash_base32(string s) { 50     string temp; 51     string ans; 52     for (int i = 0; i < s.size(); i++) { 53         temp += s[i]; 54         if ((i + 1) % 5 == 0) { 55             ans+=base32[temp]; 56             temp = ""; 57         } 58     } 59  60     return ans; 61 } 62  63 //***************** 64 //将经纬度转为base32 返回base32编码 65 //w为纬度 j为经度  66 //***************** 67 string geohash(double j, double w) { 68     string s_w="", s_j=""; 69     string s="", ss=""; 70      71     s_w = geohash_w_bin(w, -90, 90, 1, 30); 72     s_j = geohash_w_bin(j, -180, 180, 1, 30); 73      74     reverse(s_w.begin(), s_w.end()); 75     reverse(s_j.begin(), s_j.end()); 76  77     s = geohash_merge(s_j, s_w); 78     s= geohash_base32(s); 79     return s; 80 } 81  82 //有返回值的数据库写入 83 MYSQL_RES * executeQuery(char *sql) 84 { 85     MYSQL* pConn = mysql_init(0); 86     if (!mysql_real_connect(pConn, "localhost", "root", "root", "study1", 0, 0, 0)) 87     { 88         goto error; 89     } 90     if (mysql_query(pConn, "set names gbk")) 91     { 92         goto error; 93     } 94     if (mysql_query(pConn, sql)) 95     { 96         goto error; 97     } 98      99         MYSQL_RES *result = mysql_store_result(pConn);100         mysql_close(pConn);101         return result;102     103 error:104         cout << "执行出错 " << mysql_error(pConn)<<endl;105     //fprintf(cgiOut, "执行出错 %s", mysql_error(pConn));106     //printf("执行出错 %s",mysql_error(pConn));107 exit:108     mysql_close(pConn);109 }110 111 //无返回值的数据库写入112 void executeNonQuery(char * sql)113 {114     MYSQL* pConn = mysql_init(0);115     if (!mysql_real_connect(pConn, "localhost", "root", "root", "study1", 0, 0, 0))116     {117         goto error;118     }119     if (mysql_query(pConn, "set names gbk"))120     {121         goto error;122     }123     if (mysql_query(pConn, sql))124     {125         goto error;126     }127     goto exit;128 error:129     cout << "执行出错 " << mysql_error(pConn) << endl;130     /*cgiHeaderContentType("text/html;charset=gbk");131     fprintf(cgiOut, "执行出错 %s", mysql_error(pConn));*/132     //printf("执行出错 %s",mysql_error(pConn));133 exit:134     mysql_close(pConn);135 }136 137 138 //字符串截取函数139 string jiequ(string s, int l, int r) {140     string temp;141     for (int i = 0; i < r; i++)142     {143         temp += s[i];144     }145     return temp;146 }147 148 149 //输入base32编码，结果打印在屏幕上150 //查询编码前缀相同的151 void geohash_search(string base32)152 {153     for (int i = base32.size()-3; i > 0; i--)154     {155         string temp_base32 = jiequ(base32, 0, i);156         const char *temp_c_base32 = temp_base32.c_str();157         char sql[1024]; char *c = "%";158         int f = 0;159         160         sprintf(sql, "select * from t_theatre where base32 like '%s%s'", temp_c_base32,c);161         MYSQL_RES *result = executeQuery(sql);162         MYSQL_ROW row;163 164         while (row = mysql_fetch_row(result))165         {166             char *base32 = row[1];167             char *name = row[2];168             cout << base32 << " " << name << endl;169             //f = 1;170         }171 172         /*if (f) {173             return;174         }*/175 176     }177 178 179     180 181 }182 int main()183 {184     base32["00000"] = "0";185     base32["00001"] = "1";186 187     base32["00010"] = "2";188     base32["00011"] = "3";189 190     base32["00100"] = "4";191     base32["00101"] = "5";192     base32["00110"] = "6";193     base32["00111"] = "7";194 195     base32["01000"] = "8";196     base32["01001"] = "9";197     base32["01010"] = "b";//10198     base32["01011"] = "c";//11199     base32["01100"] = "d";//12200     base32["01101"] = "e";//13201     base32["01110"] = "f";//14202     base32["01111"] = "g";//15203 204     base32["10000"] = "h";//16205     base32["10001"] = "j";//17206     base32["10010"] = "k";//18207     base32["10011"] = "m";//19208     base32["10100"] = "n";//20209     base32["10101"] = "p";//21210     base32["10110"] = "q";//22211     base32["10111"] = "r";//23212     base32["11000"] = "s";//24213     base32["11001"] = "t";//25214     base32["11010"] = "u";//26215     base32["11011"] = "v";//27216     base32["11100"] = "w";//28217     base32["11101"] = "x";//29218     base32["11110"] = "y";//30219     base32["11111"] = "z";//31220 221     geohash_search("wttf1y0ewmt3");222 223     //select * from where like'wttc%'224     //geohash_search("select * from t_theatre where base32 like 'wttc%'");225     226 227     228     /*while (1) {229         double w, j; char name[128], sql[1024];230         cin >> j >> w>>name;231         232         string base32=geohash(j,w);233         const char *ch = base32.c_str();234 235         sprintf(sql, "insert into t_theatre(base32,name) values('%s','%s')", ch,name);236         executeNonQuery(sql);237     }*/238 239 240     ////insert into t_theatre(base32) values()241     //char sql[] = "insert into t_theatre(base32) values('klkl')";242     //executeNonQuery(sql);243     //120.677252 31.316891244     //cout << geohash(120.677252, 31.316891) << " 精品酒店" << endl;245     //cout << geohash(120.674144, 31.316012) << " 星海实验中学" << endl;246     //    cout<< geohash(120.648933, 31.374867) << " 相称去政府" <<endl;247     //cout << geohash(120.683958, 31.391834) << " 我的位置" <<endl;248         249     /*cout<<"111001001100011111101011100011000010110000010001010001000100";*/250     ////double a = 90.0;251     //string s=geohash_w_bin(104.031601, -180, 180, 1,30);252     //reverse(s.begin(), s.end());253     //cout << s<<endl;254     ////cout << "101010111001001000100101101010";255     ////cout << "110010011111101001100000000000";256 257     getchar();258     return 0;259 }

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最后希望自己踏实学习算法。一张纸叠n次可以比天高，而n张纸叠在一起就不一定了。

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