ceph/src/boost/libs/histogram/examples/guide_custom_modified_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_modified_axis
   8
   9 #include <boost/histogram.hpp>
  10 #include <cassert>
  11 #include <iostream>
  12 #include <sstream>
  13
  14 int main() {
  15   using namespace boost::histogram;
  16
  17   // custom axis, which adapts builtin integer axis
  18   struct custom_axis : public axis::integer<> {
  19     using value_type = const char*; // type that is fed to the axis
  20
  21     using integer::integer; // inherit ctors of base
  22
  23     // the customization point
  24     // - accept const char* and convert to int
  25     // - then call index method of base class
  26     axis::index_type index(value_type s) const { return integer::index(std::atoi(s)); }
  27   };
  28
  29   auto h = make_histogram(custom_axis(3, 6));
  30   h("-10");
  31   h("3");
  32   h("4");
  33   h("9");
  34
  35   std::ostringstream os;
  36   for (auto&& b : indexed(h)) {
  37     os << "bin " << b.index() << " [" << b.bin() << "] " << *b << "\n";
  38   }
  39
  40   std::cout << os.str() << std::endl;
  41
  42   assert(os.str() == "bin 0 [3] 1\n"
  43                      "bin 1 [4] 1\n"
  44                      "bin 2 [5] 0\n");
  45 }
  46
  47 //]