this_algorithm/test-data/generator/generate.cpp

#include <iostream>
#include <fstream>
#include <string>

#include "s2/s2earth.h"
#include "s2/s2cell_id.h"
#include "s2/s1angle.h"

using namespace std;

uint64 latLonStringsToCellId(string latString, string lonString) {
    S1Angle lat = S1Angle::Degrees(atof(latString.c_str()));
    S1Angle lon = S1Angle::Degrees(atof(lonString.c_str()));

    S2LatLng latLng = S2LatLng(lat, lon);
    // Do not normalize since this doesn't actually normalize, it clamps/truncates
    // .Normalized();

    S2CellId s2CellId = S2CellId(latLng);

    return s2CellId.id();
}

int main(int argc, char **argv) {
    fstream file;
    file.open("./00-sample-latlon.csv", fstream::in);

    if (!file) {
        cerr << "Could not open input file" << endl;
        exit(1);
    }

    fstream ofile;
    ofile.open("./01-sample-latlon-s2cpp-cellid.csv", fstream::out);

    if (!ofile) {
        cerr << "Could not open output file" << endl;
        exit(1);
    }

    string latString = "";
    string lonString = "";

    string header;
    getline(file, header, '\n');

    ofile << header << ",cellid" << "\n";

    while (getline(file, latString, ',')) {
        getline(file, lonString, '\n') ;
        uint64 generatedCellId = latLonStringsToCellId(latString, lonString);

        ofile << latString << "," << lonString << "," << generatedCellId << "\n";
    }

    cout << "Done" << endl;

    return 0;
}