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examples/tutorial/k-means_step1.cpp

This example is part of the k-means tutorial. See Step 1: Generate Random Points

/*******************************************************************************
* examples/tutorial/k-means_step1.cpp
*
* Part of Project Thrill - http://project-thrill.org
*
* Copyright (C) 2016 Timo Bingmann <[email protected]>
*
* All rights reserved. Published under the BSD-2 license in the LICENSE file.
******************************************************************************/
//! \example examples/tutorial/k-means_step1.cpp
//!
//! This example is part of the k-means tutorial. See \ref kmeans_tutorial_step1
#include <ostream>
#include <random>
using thrill::DIA;
//! [Point class]
//! A 2-dimensional point with double precision
struct Point {
//! point coordinates
double x, y;
};
//! [Point class]
//! [Point ostream]
//! make ostream-able for Print()
std::ostream& operator << (std::ostream& os, const Point& p) {
return os << '(' << p.x << ',' << p.y << ')';
}
//! [Point ostream]
//! [our main processing method]
void Process(thrill::Context& ctx) {
std::default_random_engine rng(std::random_device { } ());
std::uniform_real_distribution<double> dist(0.0, 1000.0);
// generate 100 random points using uniform distribution
DIA<Point> points =
ctx, /* size */ 100,
[&](const size_t& /* index */) {
return Point { dist(rng), dist(rng) };
})
.Cache();
// print out the points
points.Print("points");
}
//! [our main processing method]
//! [Thrill Run launcher]
int main() {
// launch Thrill program: the lambda function will be run on each worker.
return thrill::Run(
[&](thrill::Context& ctx) { Process(ctx); });
}
//! [Thrill Run launcher]
/******************************************************************************/