mirror of
https://github.com/boostorg/histogram.git
synced 2025-05-10 07:14:05 +00:00
8260deaa1d
* add tests of stdlib algorithms that use forward iterators * make accessor non-copyable, implicitly convertible to value, assign pass-through, add comparison operators * updated docs
70 lines
2.6 KiB
C++
70 lines
2.6 KiB
C++
// 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
|
|
|
|
#include <array>
|
|
#include <boost/format.hpp>
|
|
#include <boost/histogram.hpp>
|
|
#include <boost/histogram/accumulators/mean.hpp>
|
|
#include <iostream>
|
|
|
|
int main() {
|
|
using namespace boost::histogram;
|
|
const auto axis = axis::regular<>(3, 0.0, 1.0);
|
|
|
|
// Create a 1D-profile, which computes the mean of samples in each bin. The
|
|
// factory function `make_profile` is provided by the library as a shorthand.
|
|
auto h1 = make_histogram_with(dense_storage<accumulators::mean<>>(), axis);
|
|
|
|
// Argument of `sample` is passed to accumulator.
|
|
h1(0.0, sample(2)); // sample 2 goes to first bin
|
|
h1(0.1, sample(2)); // sample 2 goes to first bin
|
|
h1(0.4, sample(3)); // sample 3 goes to second bin
|
|
h1(0.5, sample(4)); // sample 4 goes to second bin
|
|
|
|
std::ostringstream os1;
|
|
for (auto&& x : indexed(h1)) {
|
|
// 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.
|
|
os1 << boost::format("%i count %i mean %.1f variance %.1f\n") % x.index() %
|
|
x->count() % x->value() % x->variance();
|
|
}
|
|
std::cout << os1.str() << std::flush;
|
|
assert(os1.str() == "0 count 2 mean 2.0 variance 0.0\n"
|
|
"1 count 2 mean 3.5 variance 0.5\n"
|
|
"2 count 0 mean 0.0 variance 0.0\n");
|
|
|
|
// Let's make a custom accumulator, which tracks the maximum of the samples. It must
|
|
// have a call operator that accepts the argument of the `sample` function. The return
|
|
// value of the call operator is ignored.
|
|
struct max {
|
|
void operator()(double x) {
|
|
if (x > value) value = x;
|
|
}
|
|
double value = 0; // value is initialized to zero
|
|
};
|
|
|
|
// Create a histogram that uses the custom accumulator.
|
|
auto h2 = make_histogram_with(dense_storage<max>(), axis);
|
|
h2(0.0, sample(2)); // sample 2 goes to first bin
|
|
h2(0.1, sample(2.5)); // sample 2.5 goes to first bin
|
|
h2(0.4, sample(3)); // sample 3 goes to second bin
|
|
h2(0.5, sample(4)); // sample 4 goes to second bin
|
|
|
|
std::ostringstream os2;
|
|
for (auto&& x : indexed(h2)) {
|
|
os2 << boost::format("%i value %.1f\n") % x.index() % x->value;
|
|
}
|
|
std::cout << os2.str() << std::flush;
|
|
assert(os2.str() == "0 value 2.5\n"
|
|
"1 value 4.0\n"
|
|
"2 value 0.0\n");
|
|
}
|
|
|
|
//]
|