add usage example

Author: hesham-saeed

examples/example.cpp

@@ -0,0 +1,77 @@
+#include <iostream>
+#include "../GridFile.h"
+#include <vector>
+#include <random>
+#include <chrono>
+
+int main(int argc, const char* argv[])
+{
+    int dimensions = 3;
+    int records = 1e8;
+    int grid_cell_size = 16384;
+    
+    try{
+            dimensions = stoi(argv[1]);
+            records = stoi(argv[2]);
+            grid_cell_size = stoi(argv[3]);
+    }
+    catch (exception e){
+        //cout << e.what() << endl;
+        cout <<"Some args are missing or failed to be parsed. Defaults will be used instead.\n\n";
+    }
+
+
+    /* Printing dataset metadata */
+    cout << "num dimensions = " << dimensions << endl;
+    cout << "num records = " << records << endl;
+    cout << "grid cell size (bytes) = " << grid_cell_size << endl;
+    cout << endl;
+
+    /* column oriented dataset. a new column begins after every set of (records). */
+    vector<uint32_t> dataset; 
+    try {
+        dataset.resize(dimensions * records);
+    }
+    catch (exception e)
+    {
+        cout << e.what();
+    }
+
+    /* Generating random data from uniform distribution. */
+    using key_type = uint32_t;
+    std::mt19937 gen(55555);
+    uniform_int_distribution<key_type> key_distrib(0, 4e9);
+    auto rand = [&gen, &key_distrib] { return key_distrib(gen); };
+    std::generate(dataset.begin(), dataset.end(), rand);
+
+
+    /* Visitor object to store the range query results. */
+    vector<vector<uint32_t>> visitor(dimensions);
+    for (int i = 0; i < visitor.size(); i++)
+    {
+        /* visitor object result structure example */
+        // attribute 1: 1, 2, 3, 394, 10
+        // attribute 2: 8, 100, 23, 123, 20
+        // attribute 3: 4, 403, 22, 99, 1, 4
+        visitor[i].resize(records);
+    }
+    gf::GridFile gridfile(dimensions, records, grid_cell_size, dataset);
+    dataset.clear();
+    dataset.shrink_to_fit();
+
+    auto start = std::chrono::high_resolution_clock::now();
+    uint64_t res = gridfile.range_query(dimensions, { 100000000,100000000, 100000000 }, { 300000000,300000000, 300000000 }, visitor);
+    auto end = std::chrono::high_resolution_clock::now();
+
+    auto duration = end - start;
+
+
+    for (int i=0;i<visitor.size();i++)
+        visitor[i].resize(res);
+    //cout <<"visitor size = " << visitor[0].size() << endl;
+    cout << "\nRange query found = " << res  << " matches"<< endl << endl;
+    std::cout << "Range query time elapsed = "
+        << std::chrono::duration_cast<std::chrono::microseconds>(duration).count()
+        << " microseconds" << std::endl;
+
+}