//[ getting_started_listing_01

#include <boost/histogram.hpp>
#include <iostream>

int main() {
  namespace bh = boost::histogram;
  using namespace bh::literals; // enables _c suffix

  /*
    create a static 1d-histogram with an axis that has 6 equidistant
    bins on the real line from -1.0 to 2.0, and label it as "x"
  */
  auto h = bh::make_static_histogram(bh::axis::regular<>(6, -1.0, 2.0, "x"));

  // fill histogram with data, typically this happens in a loop
  // STL algorithms are supported
  auto data = {-0.5, 1.1, 0.3, 1.7};
  h = std::for_each(data.begin(), data.end(), h);

  /*
    a regular axis is a sequence of semi-open bins; extra under- and
    overflow bins extend the axis in the default configuration
    index   :     -1    0    1   2   3   4   5   6
    bin edge:  -inf -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 inf
  */
  h(-1.5); // put in underflow bin -1
  h(-1.0); // put in bin 0, bin interval is semi-open
  h(2.0);  // put in overflow bin 6, bin interval is semi-open
  h(20.0); // put in overflow bin 6

  /*
    do a weighted fill using bh::weight, a wrapper for any type,
    which may appear at the beginning of the argument list
  */
  h(bh::weight(1.0), 0.1);

  /*
    iterate over bins with a fancy histogram iterator
    - order in which bins are iterated over is an implementation detail
    - iterator dereferences to histogram::element_type, which is defined by
      its storage class; by default something with value() and
      variance() methods; the first returns the
      actual count, the second returns a variance estimate of the count
      (see Rationale section for what this means)
    - idx(N) method returns the index of the N-th axis
    - bin(N_c) method returns current bin of N-th axis; the suffx _c turns
      the argument into a compile-time number, which is needed to return
      different `bin_type`s for different axes
    - `bin_type` usually is a semi-open interval representing the bin, whose
      edges can be accessed with methods `lower()` and `upper()`, but the
      implementation depends on the axis, please look it up in the reference
  */
  std::cout.setf(std::ios_base::fixed);
  for (auto it = h.begin(); it != h.end(); ++it) {
    const auto bin = it.bin(0_c);
    std::cout << "bin " << it.idx(0) << " x in [" << std::setprecision(1)
              << std::setw(4) << bin.lower() << ", " << std::setw(4)
              << bin.upper() << "): " << std::setprecision(1) << it->value()
              << " +/- " << std::setprecision(3) << std::sqrt(it->variance())
              << std::endl;
  }

  /* program output: (note that under- and overflow bins appear at the end)

  bin 0 x in [-1.0, -0.5): 1 +/- 1
  bin 1 x in [-0.5,  0.0): 0 +/- 0
  bin 2 x in [ 0.0,  0.5): 1 +/- 1
  bin 3 x in [ 0.5,  1.0): 0 +/- 0
  bin 4 x in [ 1.0,  1.5): 0 +/- 0
  bin 5 x in [ 1.5,  2.0): 0 +/- 0
  bin 6 x in [ 2.0, inf): 2 +/- 1.41421
  bin -1 x in [-inf, -1): 1 +/- 1

  */
}

//]