Added DSFMap to wrapper, as well as IndexPair

cython/gtsam/tests/test_dsf_map.py

@@ -0,0 +1,38 @@
+"""
+GTSAM Copyright 2010-2019, Georgia Tech Research Corporation,
+Atlanta, Georgia 30332-0415
+All Rights Reserved
+
+See LICENSE for the license information
+
+Unit tests for Disjoint Set Forest.
+Author: Frank Dellaert & Varun Agrawal
+"""
+# pylint: disable=invalid-name, no-name-in-module, no-member
+
+from __future__ import print_function
+
+import unittest
+
+import gtsam
+from gtsam.utils.test_case import GtsamTestCase
+
+
+class TestDSFMap(GtsamTestCase):
+    """Tests for DSFMap."""
+
+    def test_all(self):
+        """Test everything in DFSMap."""
+        def key(index_pair):
+            return index_pair.i(), index_pair.j()
+
+        dsf = gtsam.DSFMapIndexPair()
+        pair1 = gtsam.IndexPair(1, 18)
+        self.assertEqual(key(dsf.find(pair1)), key(pair1))
+        pair2 = gtsam.IndexPair(2, 2)
+        dsf.merge(pair1, pair2)
+        self.assertTrue(dsf.find(pair1), dsf.find(pair1))
+
+
+if __name__ == '__main__':
+    unittest.main()

gtsam.h

@@ -241,11 +241,28 @@ class FactorIndices {
   size_t back() const;
   void push_back(size_t factorIndex) const;
 };
+
 //*************************************************************************
 // base
 //*************************************************************************
 
 /** gtsam namespace functions */
+
+#include <gtsam/base/DSFMap.h>
+class IndexPair { 
+  IndexPair(); 
+  IndexPair(size_t i, size_t j); 
+  size_t i() const;
+  size_t j() const;
+};
+
+template<KEY = {gtsam::IndexPair}>
+class DSFMap {
+  DSFMap();
+  KEY find(const KEY& key) const;
+  void merge(const KEY& x, const KEY& y);
+};
+
 #include <gtsam/base/Matrix.h>
 bool linear_independent(Matrix A, Matrix B, double tol);
 

gtsam/base/DSFMap.h

@@ -18,9 +18,9 @@
 
 #pragma once
 
+#include <cstdlib>  // Provides size_t
 #include <map>
 #include <set>
-#include <cstdlib>        // Provides size_t
 
 namespace gtsam {
 
@@ -29,11 +29,9 @@ namespace gtsam {
  * Uses rank compression and union by rank, iterator version
  * @addtogroup base
  */
-template<class KEY>
+template <class KEY>
 class DSFMap {
-
+ protected:
-protected:
-
   /// We store the forest in an STL map, but parents are done with pointers
   struct Entry {
     typename std::map<KEY, Entry>::iterator parent_;
@@ -41,7 +39,7 @@ protected:
     Entry() {}
   };
 
-    typedef typename std::map<KEY, Entry> Map;
+  typedef typename std::map<KEY, Entry> Map;
   typedef typename Map::iterator iterator;
   mutable Map entries_;
 
@@ -62,8 +60,7 @@ protected:
   iterator find_(const iterator& it) const {
     // follow parent pointers until we reach set representative
     iterator& parent = it->second.parent_;
-    if (parent != it)
+    if (parent != it) parent = find_(parent);  // not yet, recurse!
-      parent = find_(parent); // not yet, recurse!
     return parent;
   }
 
@@ -73,13 +70,11 @@ protected:
     return find_(initial);
   }
 
-public:
+ public:
-
   typedef std::set<KEY> Set;
 
   /// constructor
-  DSFMap() {
+  DSFMap() {}
-  }
 
   /// Given key, find the representative key for the set in which it lives
   inline KEY find(const KEY& key) const {
@@ -89,12 +84,10 @@ public:
 
   /// Merge two sets
   void merge(const KEY& x, const KEY& y) {
-
     // straight from http://en.wikipedia.org/wiki/Disjoint-set_data_structure
     iterator xRoot = find_(x);
     iterator yRoot = find_(y);
-    if (xRoot == yRoot)
+    if (xRoot == yRoot) return;
-      return;
 
     // Merge sets
     if (xRoot->second.rank_ < yRoot->second.rank_)
@@ -117,7 +110,14 @@ public:
     }
     return sets;
   }
-
 };
 
-}
+/// Small utility class for representing a wrappable pairs of ints.
+class IndexPair : public std::pair<size_t,size_t> {
+ public:
+  IndexPair(): std::pair<size_t,size_t>(0,0) {}
+  IndexPair(size_t i, size_t j) : std::pair<size_t,size_t>(i,j) {}
+  inline size_t i() const { return first; };
+  inline size_t j() const { return second; };
+};
+}  // namespace gtsam

gtsam/base/tests/testDSFMap.cpp

@@ -139,6 +139,12 @@ TEST(DSFMap, sets){
   EXPECT(s2 == sets[4]);
 }
 
+/* ************************************************************************* */
+TEST(DSFMap, findIndexPair) {
+  DSFMap<IndexPair> dsf;
+  EXPECT(dsf.find(IndexPair(1,2))==IndexPair(1,2));
+  EXPECT(dsf.find(IndexPair(1,2)) != dsf.find(IndexPair(1,3)));
+}
 /* ************************************************************************* */
 int main() { TestResult tr; return TestRegistry::runAllTests(tr);}
 /* ************************************************************************* */