getting_started/rainfall.cpp
/*******************************************************
*
* The complete license agreement can be obtained at:
********************************************************/
// Investigate rainfall measurements across sites and days
// 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
// "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);
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;
}
af::seq
seq is used to create sequences for indexing af::array
Definition: seq.h:46
gfor
#define gfor(var,...)
Definition: gfor.h:33
util.h
af::info
AFAPI void info()
af::constant
array constant(T val, const dim4 &dims, const dtype ty=(af_dtype) dtype_traits< T >::ctype)
af::setDevice
AFAPI void setDevice(const int device)
Sets the current device.
af::array
A multi dimensional data container.
Definition: array.h:35
af
Definition: algorithm.h:15
af_print
#define af_print(...)
Definition: util.h:148
af::diff1
AFAPI array diff1(const array &in, const int dim=0)
C++ Interface for calculating first order differences in an array.
af::exception
An ArrayFire exception class.
Definition: exception.h:29
af::sum
AFAPI array sum(const array &in, const int dim=-1)
C++ Interface for sum of elements in an array.
arrayfire.h
af::exception::what
virtual const char * what() const
Returns an error message for the exception in a string format.
Definition: exception.h:60