ceph/src/boost/libs/histogram/examples/guide_custom_minimal_axis.cpp

   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_custom_minimal_axis
   8
   9 #include <boost/histogram.hpp>
  10 #include <cassert>
  11
  12 int main() {
  13   using namespace boost::histogram;
  14
  15   // stateless axis which returns 1 if the input is even and 0 otherwise
  16   struct even_odd_axis {
  17     axis::index_type index(int x) const { return x % 2; }
  18     axis::index_type size() const { return 2; }
  19   };
  20
  21   // threshold axis which returns 1 if the input is above threshold
  22   struct threshold_axis {
  23     threshold_axis(double x) : thr(x) {}
  24     axis::index_type index(double x) const { return x >= thr; }
  25     axis::index_type size() const { return 2; }
  26     double thr;
  27   };
  28
  29   auto h = make_histogram(even_odd_axis(), threshold_axis(3.0));
  30
  31   h(0, 2.0);
  32   h(1, 4.0);
  33   h(2, 4.0);
  34
  35   assert(h.at(0, 0) == 1); // even, below threshold
  36   assert(h.at(0, 1) == 1); // even, above threshold
  37   assert(h.at(1, 0) == 0); // odd, below threshold
  38   assert(h.at(1, 1) == 1); // odd, above threshold
  39 }
  40
  41 //]