ceph/src/boost/libs/histogram/examples/getting_started_listing_02.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 // clang-format off
   8
   9 //[ getting_started_listing_02
  10
  11 #include <boost/format.hpp>
  12 #include <boost/histogram.hpp>
  13 #include <cassert>
  14 #include <iostream>
  15 #include <sstream>
  16 #include <string>
  17
  18 int main() {
  19   using namespace boost::histogram;
  20
  21   /*
  22     Create a histogram which can be configured dynamically at run-time. The axis
  23     configuration is first collected in a vector of axis::variant type, which
  24     can hold different axis types (those in its template argument list). Here,
  25     we use a variant that can store a regular and a category axis.
  26   */
  27   using reg = axis::regular<>;
  28   using cat = axis::category<std::string>;
  29   using variant = axis::variant<axis::regular<>, axis::category<std::string>>;
  30   std::vector<variant> axes;
  31   axes.emplace_back(cat({"red", "blue"}));
  32   axes.emplace_back(reg(3, 0.0, 1.0, "x"));
  33   axes.emplace_back(reg(3, 0.0, 1.0, "y"));
  34   // passing an iterator range also works here
  35   auto h = make_histogram(std::move(axes));
  36
  37   // fill histogram with data, usually this happens in a loop
  38   h("red", 0.1, 0.2);
  39   h("blue", 0.7, 0.3);
  40   h("red", 0.3, 0.7);
  41   h("red", 0.7, 0.7);
  42
  43   /*
  44     Print histogram by iterating over bins.
  45     Since the [bin type] of the category axis cannot be converted into a double,
  46     it cannot be handled by the polymorphic interface of axis::variant. We use
  47     axis::get to "cast" the variant type to the actual category type.
  48   */
  49
  50   // get reference to category axis, performs a run-time checked static cast
  51   const auto& cat_axis = axis::get<cat>(h.axis(0));
  52   std::ostringstream os;
  53   for (auto&& x : indexed(h)) {
  54     os << boost::format("(%i, %i, %i) %4s [%3.1f, %3.1f) [%3.1f, %3.1f) %3.0f\n")
  55           % x.index(0) % x.index(1) % x.index(2)
  56           % cat_axis.bin(x.index(0))
  57           % x.bin(1).lower() % x.bin(1).upper()
  58           % x.bin(2).lower() % x.bin(2).upper()
  59           % *x;
  60   }
  61
  62   std::cout << os.str() << std::flush;
  63   assert(os.str() == "(0, 0, 0)  red [0.0, 0.3) [0.0, 0.3)   1\n"
  64                      "(1, 0, 0) blue [0.0, 0.3) [0.0, 0.3)   0\n"
  65                      "(0, 1, 0)  red [0.3, 0.7) [0.0, 0.3)   0\n"
  66                      "(1, 1, 0) blue [0.3, 0.7) [0.0, 0.3)   0\n"
  67                      "(0, 2, 0)  red [0.7, 1.0) [0.0, 0.3)   0\n"
  68                      "(1, 2, 0) blue [0.7, 1.0) [0.0, 0.3)   1\n"
  69                      "(0, 0, 1)  red [0.0, 0.3) [0.3, 0.7)   0\n"
  70                      "(1, 0, 1) blue [0.0, 0.3) [0.3, 0.7)   0\n"
  71                      "(0, 1, 1)  red [0.3, 0.7) [0.3, 0.7)   0\n"
  72                      "(1, 1, 1) blue [0.3, 0.7) [0.3, 0.7)   0\n"
  73                      "(0, 2, 1)  red [0.7, 1.0) [0.3, 0.7)   0\n"
  74                      "(1, 2, 1) blue [0.7, 1.0) [0.3, 0.7)   0\n"
  75                      "(0, 0, 2)  red [0.0, 0.3) [0.7, 1.0)   1\n"
  76                      "(1, 0, 2) blue [0.0, 0.3) [0.7, 1.0)   0\n"
  77                      "(0, 1, 2)  red [0.3, 0.7) [0.7, 1.0)   0\n"
  78                      "(1, 1, 2) blue [0.3, 0.7) [0.7, 1.0)   0\n"
  79                      "(0, 2, 2)  red [0.7, 1.0) [0.7, 1.0)   1\n"
  80                      "(1, 2, 2) blue [0.7, 1.0) [0.7, 1.0)   0\n");
  81 }
  82
  83 //]