diff --git a/CMakeLists.txt b/CMakeLists.txt
index 73fcc539a5d704f129bb780b9b66d293ef3b4579..5bad596a13f59716282e78313b2e60f10a43f2a9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -40,6 +40,7 @@ SET (${PROJECT_NAME}_HEADERS
include/hpp/statistics/bin.hh
include/hpp/statistics/success-bin.hh
include/hpp/statistics/operators.hh
+ include/hpp/statistics/distribution.hh
)
# Add dependency toward hpp-model library in pkg-config file.
diff --git a/include/hpp/statistics/distribution.hh b/include/hpp/statistics/distribution.hh
new file mode 100644
index 0000000000000000000000000000000000000000..b75f450bdb6fb3ff5f888998d0ea6f67b97f2b92
--- /dev/null
+++ b/include/hpp/statistics/distribution.hh
@@ -0,0 +1,124 @@
+// Copyright (c) 2014, LAAS-CNRS
+// Authors: Joseph Mirabel (joseph.mirabel@laas.fr)
+//
+// This file is part of hpp-statistics.
+// hpp-statistics is free software: you can redistribute it
+// and/or modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation, either version
+// 3 of the License, or (at your option) any later version.
+//
+// hpp-statistics is distributed in the hope that it will be
+// useful, but WITHOUT ANY WARRANTY; without even the implied warranty
+// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Lesser Public License for more details. You should have
+// received a copy of the GNU Lesser General Public License along with
+// hpp-statistics. If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef HPP_STATISTICS_DISTRIBUTION_HH
+# define HPP_STATISTICS_DISTRIBUTION_HH
+
+# include <vector>
+# include <stdlib.h>
+
+namespace hpp {
+ namespace statistics {
+ template < typename Value_t >
+ class DiscreteDistribution
+ {
+ public:
+ typedef double Proba_t;
+ typedef unsigned int Weight_t;
+ typedef typename std::pair < Weight_t, Value_t> ProbaTPair;
+ typedef typename std::vector < ProbaTPair >::iterator iterator;
+ typedef typename std::vector < ProbaTPair >::const_iterator const_iterator;
+
+ DiscreteDistribution () : values_(), cumulative_weights_() {}
+
+ Value_t operator() () const {
+ assert (values_.size() > 0);
+ Weight_t r = rand() % cumulative_weights_.back();
+ return operator() (r);
+ }
+ Value_t operator() (const Proba_t& p) const {
+ return operator() ((Weight_t)(p * cumulative_weights_.back ()));
+ }
+ Value_t operator() (const Weight_t& w) const {
+ assert (values_.size() > 0);
+ return values_[dichotomy (w % cumulative_weights_.back())].second;
+ }
+
+ /// Update the distribution.
+ /// If v is already in the set, then update its weight.
+ /// Otherwise, insert it.
+ void insert (Value_t v, Weight_t w = 1) {
+ iterator itv = values_.begin ();
+ WeightsIterator itcumul = cumulative_weights_.begin();
+ Weight_t c = 0;
+ while (itv != values_.end()) {
+ if (itv->second == v)
+ break;
+ c = *itcumul;
+ itv++; itcumul++;
+ }
+ if (itv == values_.end ()) {
+ values_.push_back (ProbaTPair(w,v));
+ cumulative_weights_.push_back (c + w);
+ return;
+ }
+ itv->first = w;
+ while (itv != values_.end()) {
+ c = c + itv->first;
+ *itcumul = c;
+ itv++; itcumul++;
+ }
+ }
+
+ /// Return the probabilities.
+ std::vector < Proba_t > probabilities () const {
+ std::vector < Proba_t > proba (values_.size());
+ Proba_t total = cumulative_weights_.back();
+ for (size_t i = 0; i < values_.size (); i++)
+ proba[i] = values_[i].first / total;
+ return proba;
+ }
+
+ /// \name Iterators
+ /// Iterate on the values.
+ /// \{
+ iterator begin () {
+ return values_.begin ();
+ }
+ const_iterator begin () const {
+ return values_.begin ();
+ }
+ iterator end () {
+ return values_.end ();
+ }
+ const_iterator end () const {
+ return values_.end ();
+ }
+ /// \}
+ private:
+ size_t dichotomy (const Weight_t& r) const {
+ size_t l = 0, h = values_.size () - 1, m;
+ while (l != h) {
+ m = (l + h) / 2;
+ if (cumulative_weights_[m] < r)
+ l = m;
+ else if (cumulative_weights_[m] > r)
+ h = m;
+ else
+ return m;
+ }
+ return l;
+ }
+
+ std::vector < ProbaTPair > values_;
+ std::vector < Weight_t > cumulative_weights_;
+
+ typedef std::vector < Weight_t >::iterator WeightsIterator;
+ };
+ } // namespace statistics
+} // namespace hpp
+
+#endif // HPP_STATISTICS_DISTRIBUTION_HH
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 4c27c4abf68b6a1e89f1c94afa0698f9ca390efc..a6d99391ee370b40ca0680b572b426040c37df36 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -39,3 +39,4 @@ MACRO(ADD_TESTCASE NAME GENERATED)
ENDMACRO(ADD_TESTCASE)
ADD_TESTCASE (test-successstatistics FALSE)
+ADD_TESTCASE (test-distribution FALSE)
diff --git a/tests/test-distribution.cc b/tests/test-distribution.cc
new file mode 100644
index 0000000000000000000000000000000000000000..cb8e780095a51aee3ec70b707e6e9fc8ec650af9
--- /dev/null
+++ b/tests/test-distribution.cc
@@ -0,0 +1,56 @@
+// Copyright (c) 2014, LAAS-CNRS
+// Authors: Joseph Mirabel (joseph.mirabel@laas.fr)
+//
+// This file is part of hpp-statistics.
+// hpp-statistics is free software: you can redistribute it
+// and/or modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation, either version
+// 3 of the License, or (at your option) any later version.
+//
+// hpp-statistics is distributed in the hope that it will be
+// useful, but WITHOUT ANY WARRANTY; without even the implied warranty
+// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Lesser Public License for more details. You should have
+// received a copy of the GNU Lesser General Public License along with
+// hpp-statistics. If not, see <http://www.gnu.org/licenses/>.
+
+#include <iostream>
+#include <cfloat>
+#include <time.h>
+
+#include "hpp/statistics/distribution.hh"
+
+int main ()
+{
+ /* initialize random seed: */
+ srand (time(NULL));
+
+ std::cout.precision(15);
+
+ using namespace hpp::statistics;
+ typedef DiscreteDistribution <double> Distrib;
+ Distrib dd;
+ const int nbValues = 4;
+ const double values[] = {1.0, 3.0, 2.0, 4.5};
+ const Distrib::Weight_t weight[] =
+ {1, 23, 99, 6};
+ Distrib::Weight_t total_weight = 0;
+ dd.insert (values[0], 9.0);
+ for (int i = 0; i < nbValues; i++) {
+ dd.insert (values[i], weight[i]);
+ total_weight += weight[i];
+ }
+
+ std::vector < Distrib::Proba_t > p = dd.probabilities ();
+
+ for (size_t i = 0; i < p.size (); i++)
+ if (p[i] - (double)(weight[i] / (double)total_weight) > DBL_EPSILON
+ || p[i] - (double)(weight[i] / (double)total_weight) > DBL_EPSILON) {
+ std::cout << "p[" << i << "] = " << p[i] << std::endl
+ << "weight[" << i << "] = " << weight[i] << std::endl
+ << "Total weight = " << total_weight << std::endl
+ << "Difference = " << p[i] - (double)(weight[i] / (double)total_weight) << std::endl;
+ return EXIT_FAILURE;
+ }
+ return EXIT_SUCCESS;
+}