projects / ceph.git / blame
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| 92f5a8d4 TL |
1 | // Copyright 2015-2018 Hans Dembinski |
| 2 | // | |
| 3 | // Distributed under the Boost Software License, Version 1.0. | |
| 4 | // (See accompanying file LICENSE_1_0.txt | |
| 5 | // or copy at http://www.boost.org/LICENSE_1_0.txt) | |
| 6 | ||
| 7 | //[ guide_fill_histogram | |
| 8 | ||
| 9 | #include <boost/histogram.hpp> | |
| 10 | #include <cassert> | |
| 11 | #include <functional> | |
| 12 | #include <numeric> | |
| 13 | #include <utility> | |
| 14 | #include <vector> | |
| 15 | ||
| 16 | int main() { | |
| 17 | using namespace boost::histogram; | |
| 18 | ||
| 19 | auto h = make_histogram(axis::integer<>(0, 3), axis::regular<>(2, 0.0, 1.0)); | |
| 20 | ||
| 21 | // fill histogram, number of arguments must be equal to number of axes, | |
| 22 | // types must be convertible to axis value type (here integer and double) | |
| 23 | h(0, 0.2); // increase a cell value by one | |
| 24 | h(2, 0.5); // increase another cell value by one | |
| 25 | ||
| 26 | // fills from a tuple are also supported; passing a tuple of wrong size | |
| 27 | // causes an error at compile-time or an assertion at runtime in debug mode | |
| 28 | auto xy = std::make_tuple(1, 0.3); | |
| 29 | h(xy); | |
| 30 | ||
| 31 | // chunk-wise filling is also supported and more efficient, make some data... | |
| 32 | std::vector<double> xy2[2] = {{0, 2, 5}, {0.8, 0.4, 0.7}}; | |
| 33 | ||
| 34 | // ... and call fill method | |
| 35 | h.fill(xy2); | |
| 36 | ||
| 37 | // once histogram is filled, access individual cells using operator[] or at(...) | |
| 38 | // - operator[] can only accept a single argument in the current version of C++, | |
| 39 | // it is convenient when you have a 1D histogram | |
| 40 | // - at(...) can accept several values, so use this by default | |
| 41 | // - underflow bins are at index -1, overflow bins at index `size()` | |
| 42 | // - passing an invalid index triggers a std::out_of_range exception | |
| 43 | assert(h.at(0, 0) == 1); | |
| 44 | assert(h.at(0, 1) == 1); | |
| 45 | assert(h.at(1, 0) == 1); | |
| 46 | assert(h.at(1, 1) == 0); | |
| 47 | assert(h.at(2, 0) == 1); | |
| 48 | assert(h.at(2, 1) == 1); | |
| 49 | assert(h.at(-1, -1) == 0); // underflow for axis 0 and 1 | |
| 50 | assert(h.at(-1, 0) == 0); // underflow for axis 0, normal bin for axis 1 | |
| 51 | assert(h.at(-1, 2) == 0); // underflow for axis 0, overflow for axis 1 | |
| 52 | assert(h.at(3, 1) == 1); // overflow for axis 0, normal bin for axis 1 | |
| 53 | ||
| 54 | // iteration over values works, but see next example for a better way | |
| 55 | // - iteration using begin() and end() includes under- and overflow bins | |
| 56 | // - iteration order is an implementation detail and should not be relied upon | |
| 57 | const double sum = std::accumulate(h.begin(), h.end(), 0.0); | |
| 58 | assert(sum == 6); | |
| 59 | } | |
| 60 | ||
| 61 | //] |