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
59 lines
1.8 KiB
C++
59 lines
1.8 KiB
C++
// Copyright 2015-2018 Hans Dembinski
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//
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt
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// or copy at http://www.boost.org/LICENSE_1_0.txt)
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//[ guide_histogram_projection
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#include <boost/histogram.hpp>
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#include <cassert>
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#include <iostream>
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#include <sstream>
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int main() {
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using namespace boost::histogram;
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using namespace literals; // enables _c suffix
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// make a 2d histogram
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auto h = make_histogram(axis::regular<>(3, -1.0, 1.0), axis::integer<>(0, 2));
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h(-0.9, 0);
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h(0.9, 1);
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h(0.1, 0);
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auto hr0 = algorithm::project(h, 0_c); // keep only first axis
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auto hr1 = algorithm::project(h, 1_c); // keep only second axis
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// reduce does not remove counts; returned histograms are summed over
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// the removed axes, so h, hr0, and hr1 have same number of total counts;
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// we compute the sum of counts with the sum algorithm
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assert(algorithm::sum(h) == 3 && algorithm::sum(hr0) == 3 && algorithm::sum(hr1) == 3);
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std::ostringstream os1;
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for (auto&& x : indexed(h))
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os1 << "(" << x.index(0) << ", " << x.index(1) << "): " << *x << "\n";
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std::cout << os1.str() << std::flush;
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assert(os1.str() == "(0, 0): 1\n"
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"(1, 0): 1\n"
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"(2, 0): 0\n"
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"(0, 1): 0\n"
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"(1, 1): 0\n"
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"(2, 1): 1\n");
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std::ostringstream os2;
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for (auto&& x : indexed(hr0)) os2 << "(" << x.index(0) << ", -): " << *x << "\n";
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std::cout << os2.str() << std::flush;
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assert(os2.str() == "(0, -): 1\n"
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"(1, -): 1\n"
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"(2, -): 1\n");
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std::ostringstream os3;
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for (auto&& x : indexed(hr1)) os3 << "(- ," << x.index(0) << "): " << *x << "\n";
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std::cout << os3.str() << std::flush;
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assert(os3.str() == "(- ,0): 2\n"
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"(- ,1): 1\n");
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}
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//]
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