getting_started/rainfall.cpp

/*******************************************************
 * Copyright (c) 2014, ArrayFire
 * All rights reserved.
 *
 * This file is distributed under 3-clause BSD license.
 * The complete license agreement can be obtained at:
 * http://arrayfire.com/licenses/BSD-3-Clause
 ********************************************************/
 
// Investigate rainfall measurements across sites and days
// demonstrating various simple tasks
 
// Compute various values:
// - total rainfall at each site
// - rain between days 1 and 5
// - number of days with rain
// - total rainfall on each day
// - number of days with over five inches
// - total rainfall at each site
 
// note: example adapted from
//  "Rapid Problem Solving Using Thrust", Nathan Bell, NVIDIA
 
#include <arrayfire.h>
#include <stdio.h>
#include <af/util.h>
#include <cstdlib>
using namespace af;
 
int main(int argc, char **argv) {
    try {
        int device = argc > 1 ? atoi(argv[1]) : 0;
        af::setDevice(device);
        af::info();
 
        int days = 9, sites = 4;
        int n                = 10;                              // measurements
        float day_[]         = {0, 0, 1, 2, 5, 5, 6, 6, 7, 8};  // ascending
        float site_[]        = {2, 3, 0, 1, 1, 2, 0, 1, 2, 1};
        float measurement_[] = {9, 5, 6, 3, 3, 8, 2, 6, 5, 10};  // inches
        array day(n, day_);
        array site(n, site_);
        array measurement(n, measurement_);
 
        array rainfall = constant(0, sites);
        gfor(seq s, sites) { rainfall(s) = sum(measurement * (site == s)); }
 
        printf("total rainfall at each site:\n");
        af_print(rainfall);
 
        array is_between   = 1 <= day && day <= 5;  // days 1 and 5
        float rain_between = sum<float>(measurement * is_between);
        printf("rain between days: %g\n", rain_between);
 
        printf("number of days with rain: %g\n",
               sum<float>(diff1(day) > 0) + 1);
 
        array per_day                = constant(0, days);
        gfor(seq d, days) per_day(d) = sum(measurement * (day == d));
 
        printf("total rainfall each day:\n");
        af_print(per_day);
 
        printf("number of days over five: %g\n", sum<float>(per_day > 5));
    } catch (af::exception &e) {
        fprintf(stderr, "%s\n", e.what());
        throw;
    }
 
    return 0;
}