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// Copyright 2018 Hans Dembinski
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt
// or copy at http://www.boost.org/LICENSE_1_0.txt)
//[ guide_custom_accumulators_simple
#include <boost/format.hpp>
#include <boost/histogram.hpp>
#include <cassert>
#include <iostream>
#include <sstream>
int main() {
using namespace boost::histogram;
// A custom accumulator which tracks the maximum of the samples.
// It must have a call operator that accepts the argument of the `sample` function.
struct maximum {
// return value is ignored, so we use void
void operator()(double x) {
if (x > value) value = x;
}
double value = 0; // value is public and initialized to zero
};
// Create 1D histogram that uses the custom accumulator.
auto h = make_histogram_with(dense_storage<maximum>(), axis::integer<>(0, 2));
h(0, sample(1.0)); // sample goes to first cell
h(0, sample(2.0)); // sample goes to first cell
h(1, sample(3.0)); // sample goes to second cell
h(1, sample(4.0)); // sample goes to second cell
std::ostringstream os;
for (auto&& x : indexed(h)) {
os << boost::format("index %i maximum %.1f\n") % x.index() % x->value;
}
std::cout << os.str() << std::flush;
assert(os.str() == "index 0 maximum 2.0\n"
"index 1 maximum 4.0\n");
}
//]
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