Examples.cc

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/*
 * (C) Copyright 1996-2012 ECMWF.
 *
 * This software is licensed under the terms of the Apache Licence Version 2.0
 * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
 * In applying this licence, ECMWF does not waive the privileges and immunities
 * granted to it by virtue of its status as an intergovernmental organisation nor
 * does it submit to any jurisdiction.
 */
 
/// This file contains examples of usage of public APIs.
 
#include <string>
#include <iostream>
#include <vector>
 
#include "eckit/filesystem/PathName.h"
#include "eckit/io/FileHandle.h"
 
#include "odc/api/Odb.h"
 
#include "odc/Select.h"
#include "odc/Reader.h"
#include "odc/Writer.h"
 
#include "TestCase.h"
 
using namespace eckit;
 
namespace {
 
TEST(example_select_data_read_results)
{
    // Prepare input data
    const std::string data =
        R"(x:INTEGER,y:INTEGER,v:DOUBLE
        1,1,0.3
        1,1,0.2
        2,2,0.4
        2,2,0.1)";
 
    FileHandle out("example_select_data_read_results.odb");
    out.openForWrite(0);
    AutoClose close(out);
    odc::api::odbFromCSV(data, out);
 
    odc::Select select("select x,min(v),max(v);", "example_select_data_read_results.odb");
 
    for (odc::Select::iterator it (select.begin()),
                               end (select.end());
         it != end;
         ++it)
    {
        double r0 = (*it)[0],
               r1 = (*it)[1],
               r2 = (*it)[2];
 
        std::cout << r0 << ", " << r1 << ", " << r2 << std::endl;
    }
}
 
 
TEST(example_read_data)
{
    // Prepare input data
    const std::string data = "x:INTEGER,y:INTEGER,v:DOUBLE\n" "1,1,0.3\n" "1,1,0.2\n" "2,2,0.4\n" "2,2,0.1\n";
    FileHandle out("example_read_data.odb");
    out.openForWrite(0);
    AutoClose close(out);
    odc::api::odbFromCSV(data, out);
 
    odc::Reader o("example_read_data.odb");
    for (odc::Reader::iterator it (o.begin()),
                               end (o.end());
         it != end;
         ++it)
    {
        double r0 = (*it)[0],
               r1 = (*it)[1],
               r2 = (*it)[2];
 
        std::cout << r0 << ", " << r1 << ", " << r2 << std::endl;
    }
}
 
TEST(example_write_data)
{
    odc::core::MetaData metaData;
    metaData
        .addColumn("x", "INTEGER")
        .addColumn("y", "INTEGER")
        .addColumn("v", "DOUBLE");
 
    odc::Writer<> writer("example_write_data.odb");
    odc::Writer<>::iterator it (writer.begin());
    it->columns(metaData);
    it->writeHeader();
 
    for (size_t i (1); i <= 1000; ++i)
    {
        (*it)[0] = i;
        (*it)[1] = i*2;
        (*it)[2] = i*3;
 
        // Incrementing iterator moves coursor to the next row.
        ++it;
    }
}
 
} // namespace