From c2e22942c35e894d5c1ddc429eb32687c61538c8 Mon Sep 17 00:00:00 2001
From: Marc Glisse <marc.glisse@inria.fr>
Date: Thu, 26 Dec 2019 10:22:47 +0100
Subject: Basic binding for wasserstein_distance

---
 src/python/gudhi/hera.cc | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 src/python/gudhi/hera.cc

(limited to 'src/python/gudhi/hera.cc')

diff --git a/src/python/gudhi/hera.cc b/src/python/gudhi/hera.cc
new file mode 100644
index 00000000..7cef9425
--- /dev/null
+++ b/src/python/gudhi/hera.cc
@@ -0,0 +1,48 @@
+#include <pybind11/pybind11.h>
+#include <pybind11/numpy.h>
+
+#include <boost/range/iterator_range.hpp>
+
+#include <wasserstein.h>
+
+#include <array>
+
+namespace py = pybind11;
+typedef py::array_t<double, py::array::c_style | py::array::forcecast> Dgm;
+
+namespace hera {
+template <> struct DiagramTraits<Dgm>{
+  //using Container = void;
+  using PointType = std::array<double,2>;
+  using RealType  = double;
+
+  static RealType get_x(const PointType& p) { return std::get<0>(p); }
+  static RealType get_y(const PointType& p) { return std::get<1>(p); }
+};
+}
+
+double wasserstein_distance(
+    Dgm d1,
+    Dgm d2)
+{
+  py::buffer_info buf1 = d1.request();
+  py::buffer_info buf2 = d2.request();
+  if(buf1.ndim!=2 || buf1.shape[1]!=2)
+    throw std::runtime_error("Diagram 1 must be an array of size n x 2");
+  if(buf2.ndim!=2 || buf2.shape[1]!=2)
+    throw std::runtime_error("Diagram 1 must be an array of size n x 2");
+  typedef hera::DiagramTraits<Dgm>::PointType Point;
+  auto p1 = (Point*)buf1.ptr;
+  auto p2 = (Point*)buf2.ptr;
+  auto diag1 = boost::make_iterator_range(p1, p1+buf1.shape[0]);
+  auto diag2 = boost::make_iterator_range(p2, p2+buf2.shape[0]);
+
+  hera::AuctionParams<double> params;
+  return hera::wasserstein_dist(diag1, diag2, params);
+}
+
+PYBIND11_MODULE(hera, m) {
+      m.def("wasserstein_distance", &wasserstein_distance, R"pbdoc(
+        Compute the Wasserstein distance between two diagrams
+    )pbdoc");
+}
-- 
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