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

   1 // Copyright 2019 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 // clang-format off
   8
   9 //[ guide_axis_growing
  10
  11 #include <boost/histogram.hpp>
  12 #include <cassert>
  13
  14 #include <iostream>
  15
  16 int main() {
  17   using namespace boost::histogram;
  18
  19   // make a growing regular axis
  20   // - it grows new bins with its constant bin width until the value is covered
  21   auto h1 = make_histogram(axis::regular<double,
  22                                          use_default,
  23                                          use_default,
  24                                          axis::option::growth_t>{2, 0., 1.});
  25   // nothing special happens here
  26   h1(0.1);
  27   h1(0.9);
  28   // state: [0, 0.5): 1, [0.5, 1.0): 1
  29   assert(h1.axis().size() == 2);
  30   assert(h1.axis().bin(0).lower() == 0.0);
  31   assert(h1.axis().bin(1).upper() == 1.0);
  32
  33   // value below range: axis grows new bins until value is in range
  34   h1(-0.3);
  35   // state: [-0.5, 0.0): 1, [0, 0.5): 1, [0.5, 1.0): 1
  36   assert(h1.axis().size() == 3);
  37   assert(h1.axis().bin(0).lower() == -0.5);
  38   assert(h1.axis().bin(2).upper() == 1.0);
  39
  40   h1(1.9);
  41   // state: [-0.5, 0.0): 1, [0, 0.5): 1, [0.5, 1.0): 1, [1.0, 1.5): 0 [1.5, 2.0): 1
  42   assert(h1.axis().size() == 5);
  43   assert(h1.axis().bin(0).lower() == -0.5);
  44   assert(h1.axis().bin(4).upper() == 2.0);
  45
  46   // make a growing category axis (here strings)
  47   // - empty axis is allowed: very useful if categories are not known at the beginning
  48   auto h2 = make_histogram(axis::category<std::string,
  49                                           use_default,
  50                                           axis::option::growth_t>());
  51   assert(h2.size() == 0); // histogram is empty
  52   h2("foo"); // new bin foo, index 0
  53   assert(h2.size() == 1);
  54   h2("bar"); // new bin bar, index 1
  55   assert(h2.size() == 2);
  56   h2("foo");
  57   assert(h2.size() == 2);
  58   assert(h2[0] == 2);
  59   assert(h2[1] == 1);
  60 }
  61
  62 //]