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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_builtin
#include <boost/format.hpp>
#include <boost/histogram.hpp>
#include <cassert>
#include <iostream>
#include <sstream>
int main() {
using namespace boost::histogram;
using mean = accumulators::mean<>;
// Create a 1D-profile, which computes the mean of samples in each bin.
auto h = make_histogram_with(dense_storage<mean>(), axis::integer<>(0, 2));
// The factory function `make_profile` is provided as a shorthand for this, so this is
// equivalent to the previous line: auto h = make_profile(axis::integer<>(0, 2));
// An argument marked as `sample` is passed to the accumulator.
h(0, sample(1)); // sample goes to first cell
h(0, sample(2)); // sample goes to first cell
h(1, sample(3)); // sample goes to second cell
h(1, sample(4)); // sample goes to second cell
std::ostringstream os;
for (auto&& x : indexed(h)) {
// Accumulators usually have methods to access their state. Use the arrow
// operator to access them. Here, `count()` gives the number of samples,
// `value()` the mean, and `variance()` the variance estimate of the mean.
os << boost::format("index %i count %i mean %.1f variance %.1f\n") % x.index() %
x->count() % x->value() % x->variance();
}
std::cout << os.str() << std::flush;
assert(os.str() == "index 0 count 2 mean 1.5 variance 0.5\n"
"index 1 count 2 mean 3.5 variance 0.5\n");
}
//]
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