Add python bindings for attribute read/write (#1156)

* add python bindings for attribute read/write

* fix string conversion

* fix test typo

* fix string conversion

networkit/graph.pxd

@@ -179,6 +179,8 @@ cdef extern from "<networkit/graph/Graph.hpp>":
 		void set(node, int) except +
 		int get(node) except +
 		int get(node, int) except +
+		void write(string) except +
+		void read(string) except +
 		void swap(_NodeIntAttribute& other)
 		string getName() except +	
 
@@ -195,6 +197,8 @@ cdef extern from "<networkit/graph/Graph.hpp>":
 		void set(node, double) except +
 		double get(node) except +
 		double get(node, double) except +
+		void write(string) except +
+		void read(string) except +
 		void swap(_NodeDoubleAttribute& other)
 		string getName() except +
 
@@ -211,6 +215,8 @@ cdef extern from "<networkit/graph/Graph.hpp>":
 		void set(node, string) except +
 		string get(node) except +
 		string get(node, string) except +
+		void write(string) except +
+		void read(string) except +
 		void swap(_NodeStringAttribute& other)
 		string getName() except +
 
@@ -230,6 +236,8 @@ cdef extern from "<networkit/graph/Graph.hpp>":
 		int get2(node, node) except +
 		int get(edgeid, int) except +
 		int get2(node, node, int) except +
+		void write(string) except +
+		void read(string) except +
 		void swap(_EdgeIntAttribute& other)
 
 cdef extern from "<networkit/graph/Graph.hpp>":
@@ -248,6 +256,8 @@ cdef extern from "<networkit/graph/Graph.hpp>":
 		double get2(node, node) except +
 		double get(edgeid, double) except +
 		double get2(node, node, double) except +
+		void write(string) except +
+		void read(string) except +
 		void swap(_EdgeDoubleAttribute& other)
 
 cdef extern from "<networkit/graph/Graph.hpp>":
@@ -266,6 +276,8 @@ cdef extern from "<networkit/graph/Graph.hpp>":
 		string get2(node, node) except +
 		string get(edgeid, string) except +
 		string get2(node, node, string) except +
+		void write(string) except +
+		void read(string) except +
 		void swap(_EdgeStringAttribute& other)
 
 cdef class Graph:

networkit/graph.pyx

@@ -1164,6 +1164,12 @@ cdef class NodeIntAttribute:
 		preincrement(self._iter)
 		return val
 
+	def write(self, path: str):
+		return self._this.write(stdstring(path))
+
+	def read(self, path: str):
+		return self._this.read(stdstring(path))
+
 
 cdef class NodeDoubleAttribute:
 	cdef setThis(self, _NodeDoubleAttribute& other, _Graph* G):
@@ -1202,6 +1208,12 @@ cdef class NodeDoubleAttribute:
 		preincrement(self._iter)
 		return val
 
+	def write(self, path: str):
+		return self._this.write(stdstring(path))
+
+	def read(self, path: str):
+		return self._this.read(stdstring(path))
+
 cdef class NodeStringAttribute:
 
 	cdef setThis(self, _NodeStringAttribute& other, _Graph* G):
@@ -1241,6 +1253,12 @@ cdef class NodeStringAttribute:
 		preincrement(self._iter)
 		return val
 
+	def write(self, path: str):
+		return self._this.write(stdstring(path))
+
+	def read(self, path: str):
+		return self._this.read(stdstring(path))
+
 class NodeAttribute:
 	"""
 	Generic class for node attributes returned by networkit.graph.attachNodeAttribute().
@@ -1290,6 +1308,12 @@ class NodeAttribute:
 
 	def __next__(self):
 		return next(self._iter)
+
+	def write(self, path: str):
+		return self.attr.write(path)
+
+	def read(self, path: str):
+		return self.attr.read(path)
 
 
 # The following 3 classes EdgeIntAttribute, EdgeDoubleAttribute and 
@@ -1351,6 +1375,11 @@ cdef class EdgeIntAttribute:
 		preincrement(self._iter)
 		return val
 
+	def write(self, path: str):
+		return self._this.write(stdstring(path))
+
+	def read(self, path: str):
+		return self._this.read(stdstring(path))
 
 cdef class EdgeDoubleAttribute:
 	cdef setThis(self, _EdgeDoubleAttribute& other, _Graph* G):
@@ -1402,6 +1431,12 @@ cdef class EdgeDoubleAttribute:
 		val = dereference(self._iter)
 		preincrement(self._iter)
 		return val
+
+	def write(self, path: str):
+		return self._this.write(stdstring(path))
+
+	def read(self, path: str):
+		return self._this.read(stdstring(path))
 
 cdef class EdgeStringAttribute:
 
@@ -1455,6 +1490,12 @@ cdef class EdgeStringAttribute:
 		val = (val[0], pystring(val[1]))
 		preincrement(self._iter)
 		return val
+
+	def write(self, path: str):
+		return self._this.write(stdstring(path))
+
+	def read(self, path: str):
+		return self._this.read(stdstring(path))
 
 class EdgeAttribute:
 	"""
@@ -1503,6 +1544,12 @@ class EdgeAttribute:
 	def __next__(self):
 		return next(self._iter)
 
+	def write(self, path: str):
+		return self.attr.write(path)
+
+	def read(self, path: str):
+		return self.attr.read(path)
+
 
 cdef cppclass EdgeCallBackWrapper:
 	void* callback

networkit/test/test_graph.py

@@ -302,6 +302,24 @@ def testNodeAttributes(self):
 
 			G.detachNodeAttribute("attribute")
 
+	def testNodeAttributeReadWrite(self):
+		G = nk.Graph(5)
+
+		for attType in [int, float, str]:
+			attVals = [attType(u) for u in G.iterNodes()]
+
+			attrs = G.attachNodeAttribute("attribute", attType)
+			attrsRead = G.attachNodeAttribute("attributeRead", attType)
+			for u in G.iterNodes():
+				attrs[u] = attVals[u]
+			attrs.write('test.attrs')
+			attrsRead.read('test.attrs')
+			for u in G.iterNodes():
+				self.assertEqual(attrs[u], attrsRead[u])
+
+			G.detachNodeAttribute("attribute")
+			G.detachNodeAttribute("attributeRead")
+
 	def testEdgeAttributesMandatoryIndexing(self):
 		G = nk.Graph(5)
 		with self.assertRaises(Exception):
@@ -352,6 +370,30 @@ def testEdgeAttributesByNodePair(self):
 				self.assertEqual(attrs[u,v], attVals[u])
 
 			G.detachEdgeAttribute("attribute")
+
+	def testEdgeAttributeReadWrite(self):
+		G = nk.Graph(5)
+		G.indexEdges()
+
+		G.addEdge(0, 1)
+		G.addEdge(0, 2)
+		G.addEdge(1, 3)
+		G.addEdge(2, 4)
+
+		for attType in [int, float, str]:
+			attVals = [attType(u+v) for u,v in G.iterEdges()]
+
+			attrs = G.attachEdgeAttribute("attribute", attType)
+			attrsRead = G.attachEdgeAttribute("attributeRead", attType)
+			for u,v in G.iterEdges():
+				attrs[u,v] = attVals[u]
+			attrs.write('test.attrs')
+			attrsRead.read('test.attrs')
+			for u,v in G.iterEdges():
+				self.assertEqual(attrs[u,v], attrsRead[u,v])
+
+			G.detachEdgeAttribute("attribute")
+			G.detachEdgeAttribute("attributeRead")
 
 	def testRandomEdgesReproducibility(self):
 		numSamples = 10