feat: Add modular centrality score

Author: Anton Eriksson

interfaces/js/src/filetypes.ts

@@ -13,6 +13,7 @@ export interface TreeNode {
   path: number[];
   modules?: number[];
   flow?: number;
+  modularCentrality?: number;
   name?: string;
   id: number;
 }

interfaces/swig/InfomapIterator.i

@@ -75,6 +75,17 @@ namespace std {
 			"""
 			return self._depth()
 
+		@property
+		def modular_centrality(self):
+			"""Get the modular centrality of the node.
+
+			Returns
+			-------
+			float
+				The modular centrality
+			"""
+			return self.modularCentrality()
+
 		@property
 		def child_index(self):
 			"""Get the child index.
@@ -151,6 +162,17 @@ namespace std {
 			"""
 			return self._depth()
 
+		@property
+		def modular_centrality(self):
+			"""Get the modular centrality of the node.
+
+			Returns
+			-------
+			float
+				The modular centrality
+			"""
+			return self.modularCentrality()
+
 		@property
 		def child_index(self):
 			"""Get the child index.
@@ -228,6 +250,17 @@ namespace std {
 			"""
 			return self._depth()
 
+		@property
+		def modular_centrality(self):
+			"""Get the modular centrality of the node.
+
+			Returns
+			-------
+			float
+				The modular centrality
+			"""
+			return self.modularCentrality()
+
 		@property
 		def child_index(self):
 			"""Get the child index.
@@ -305,6 +338,17 @@ namespace std {
 			"""
 			return self._depth()
 
+		@property
+		def modular_centrality(self):
+			"""Get the modular centrality of the node.
+
+			Returns
+			-------
+			float
+				The modular centrality
+			"""
+			return self.modularCentrality()
+
 		@property
 		def child_index(self):
 			"""Get the child index.
@@ -382,6 +426,17 @@ namespace std {
 			"""
 			return self._depth()
 
+		@property
+		def modular_centrality(self):
+			"""Get the modular centrality of the node.
+
+			Returns
+			-------
+			float
+				The modular centrality
+			"""
+			return self.modularCentrality()
+
 		@property
 		def child_index(self):
 			"""Get the child index.

src/core/InfomapBase.cpp

@@ -2629,6 +2629,7 @@ void InfomapBase::writeJsonTree(std::ostream& outStream, bool states, bool write
                   << "\"modules\": [" << modules << "], "
                   << "\"name\": \"" << nodeName(node) << "\", "
                   << "\"flow\": " << node.data.flow << ", "
+                  << "\"modularCentrality\": " << it.modularCentrality() << ", "
                   << "\"id\": " << node.physicalId << " }";
       }
     }
@@ -2653,7 +2654,8 @@ void InfomapBase::writeJsonTree(std::ostream& outStream, bool states, bool write
                   << "\"path\": [" << path << "], "
                   << "\"modules\": [" << modules << "], "
                   << "\"name\": \"" << nodeName(node) << "\", "
-                  << "\"flow\": " << node.data.flow << ", ";
+                  << "\"flow\": " << node.data.flow << ", "
+                  << "\"modularCentrality\": " << it.modularCentrality() << ", ";
 
         if (states) {
           outStream << "\"stateId\": " << node.stateId << ", ";

src/core/InfomapIterator.h

@@ -8,6 +8,7 @@
 
 #include <deque>
 #include <map>
+#include <cmath>
 #include "InfoNode.h"
 
 namespace infomap {
@@ -141,6 +142,24 @@ struct InfomapIterator {
     return m_depth;
   }
 
+  double modularCentrality() const
+  {
+    if (m_current->parent == nullptr) {
+      // The root node has no modular centrality
+      return 0.0;
+    }
+
+    const auto p_m = m_current->parent->data.flow;
+    const auto p_u = m_current->data.flow;
+    const auto p_diff = p_m - p_u;
+
+    if (p_diff > 0.0) {
+      return -p_diff * std::log2(p_diff / p_m);
+    }
+
+    return 0.0;
+  }
+
   bool isEnd() const
   {
     return m_current == nullptr;
@@ -175,6 +194,7 @@ struct InfomapModuleIterator : public InfomapIterator {
   using InfomapIterator::childIndex;
   using InfomapIterator::current;
   using InfomapIterator::depth;
+  using InfomapIterator::modularCentrality;
   using InfomapIterator::path;
 };
 
@@ -217,6 +237,7 @@ struct InfomapLeafModuleIterator : public InfomapIterator {
   using InfomapIterator::childIndex;
   using InfomapIterator::current;
   using InfomapIterator::depth;
+  using InfomapIterator::modularCentrality;
   using InfomapIterator::path;
 };
 
@@ -259,6 +280,7 @@ struct InfomapLeafIterator : public InfomapIterator {
   using InfomapIterator::childIndex;
   using InfomapIterator::current;
   using InfomapIterator::depth;
+  using InfomapIterator::modularCentrality;
   using InfomapIterator::path;
 };
 
@@ -315,6 +337,7 @@ struct InfomapIteratorPhysical : public InfomapIterator {
   using InfomapIterator::childIndex;
   using InfomapIterator::current;
   using InfomapIterator::depth;
+  using InfomapIterator::modularCentrality;
   using InfomapIterator::path;
 };
 
@@ -363,6 +386,7 @@ struct InfomapLeafIteratorPhysical : public InfomapIteratorPhysical {
   using InfomapIteratorPhysical::childIndex;
   using InfomapIteratorPhysical::current;
   using InfomapIteratorPhysical::depth;
+  using InfomapIteratorPhysical::modularCentrality;
   using InfomapIteratorPhysical::path;
 };