Adding upstream version 14.2.21.upstream/14.2.21upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 58 insertions, 0 deletions

diff --git a/src/boost/libs/histogram/examples/guide_histogram_projection.cpp b/src/boost/libs/histogram/examples/guide_histogram_projection.cpp
new file mode 100644
index 00000000..54f45212
--- /dev/null
+++ b/src/boost/libs/histogram/examples/guide_histogram_projection.cpp
@@ -0,0 +1,58 @@
+// Copyright 2015-2018 Hans Dembinski
+//
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt
+// or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+//[ guide_histogram_projection
+
+#include <boost/histogram.hpp>
+#include <cassert>
+#include <iostream>
+#include <sstream>
+
+int main() {
+  using namespace boost::histogram;
+  using namespace literals; // enables _c suffix
+
+  // make a 2d histogram
+  auto h = make_histogram(axis::regular<>(3, -1.0, 1.0), axis::integer<>(0, 2));
+
+  h(-0.9, 0);
+  h(0.9, 1);
+  h(0.1, 0);
+
+  auto hr0 = algorithm::project(h, 0_c); // keep only first axis
+  auto hr1 = algorithm::project(h, 1_c); // keep only second axis
+
+  // reduce does not remove counts; returned histograms are summed over
+  // the removed axes, so h, hr0, and hr1 have same number of total counts;
+  // we compute the sum of counts with the sum algorithm
+  assert(algorithm::sum(h) == 3 && algorithm::sum(hr0) == 3 && algorithm::sum(hr1) == 3);
+
+  std::ostringstream os1;
+  for (auto&& x : indexed(h))
+    os1 << "(" << x.index(0) << ", " << x.index(1) << "): " << *x << "\n";
+  std::cout << os1.str() << std::flush;
+  assert(os1.str() == "(0, 0): 1\n"
+                      "(1, 0): 1\n"
+                      "(2, 0): 0\n"
+                      "(0, 1): 0\n"
+                      "(1, 1): 0\n"
+                      "(2, 1): 1\n");
+
+  std::ostringstream os2;
+  for (auto&& x : indexed(hr0)) os2 << "(" << x.index(0) << ", -): " << *x << "\n";
+  std::cout << os2.str() << std::flush;
+  assert(os2.str() == "(0, -): 1\n"
+                      "(1, -): 1\n"
+                      "(2, -): 1\n");
+
+  std::ostringstream os3;
+  for (auto&& x : indexed(hr1)) os3 << "(- ," << x.index(0) << "): " << *x << "\n";
+  std::cout << os3.str() << std::flush;
+  assert(os3.str() == "(- ,0): 2\n"
+                      "(- ,1): 1\n");
+}
+
+//]