document and test api functions

graphtools/api.py

@@ -231,7 +231,28 @@ def Graph(data,
 
 
 def from_igraph(G, **kwargs):
-    if 'precomputed' in kwargs and kwargs['precomputed'] != 'adjacency':
-        raise ValueError("Cannot build graph from igraph with precomputed={}. "
-                         "Use 'adjacency' instead.".format(kwargs['precomputed']))
-    return Graph(sparse.coo_matrix(G.get_adjacency().data), precomputed='adjacency', **kwargs)
+    """Convert an igraph.Graph to a graphtools.Graph
+
+    Creates a graphtools.graphs.TraditionalGraph with a
+    precomputed adjacency matrix
+
+    Parameters
+    ----------
+    G : igraph.Graph
+        Graph to be converted
+    kwargs
+        keyword arguments for graphtools.Graph
+
+    Returns
+    -------
+    G : graphtools.graphs.TraditionalGraph
+    """
+    if 'precomputed' in kwargs:
+        if kwargs['precomputed'] != 'adjacency':
+            warnings.warn(
+                "Cannot build graph from igraph with precomputed={}. "
+                "Use 'adjacency' instead.".format(kwargs['precomputed']),
+                UserWarning)
+        del kwargs['precomputed']
+    return Graph(sparse.coo_matrix(G.get_adjacency().data),
+                 precomputed='adjacency', **kwargs)

graphtools/base.py

@@ -535,9 +535,41 @@ def build_kernel(self):
         """
         raise NotImplementedError
 
-    def to_pygsp(self):
+    def to_pygsp(self, **kwargs):
+        """Convert to a PyGSP graph
+
+        For use only when the user means to create the graph using
+        the flag `use_pygsp=True`, and doesn't wish to recompute the kernel.
+        Creates a graphtools.graphs.TraditionalGraph with a precomputed
+        affinity matrix which also inherits from pygsp.graphs.Graph.
+
+        Parameters
+        ----------
+        kwargs
+            keyword arguments for graphtools.Graph
+
+        Returns
+        -------
+        G : graphtools.base.PyGSPGraph, graphtools.graphs.TraditionalGraph
+        """
         from . import api
-        return api.Graph(self.K, precomputed="affinity", use_pygsp=True)
+        if 'precomputed' in kwargs:
+            if kwargs['precomputed'] != 'affinity':
+                warnings.warn(
+                    "Cannot build PyGSPGraph with precomputed={}. "
+                    "Using 'affinity' instead.".format(kwargs['precomputed']),
+                    UserWarning)
+            del kwargs['precomputed']
+        if 'use_pygsp' in kwargs:
+            if kwargs['use_pygsp'] is not True:
+                warnings.warn(
+                    "Cannot build PyGSPGraph with use_pygsp={}. "
+                    "Use True instead.".format(kwargs['use_pygsp']),
+                    UserWarning)
+            del kwargs['use_pygsp']
+        return api.Graph(self.K,
+                         precomputed="affinity", use_pygsp=True,
+                         **kwargs)
 
 
 class PyGSPGraph(with_metaclass(abc.ABCMeta, pygsp.graphs.Graph, Base)):

test/test_api.py

@@ -3,6 +3,7 @@
     data,
     build_graph,
     raises,
+    warns,
 )
 import warnings
 
@@ -24,12 +25,36 @@ def test_from_igraph():
     assert np.all(G.K == G2.K)
 
 
+@warns(UserWarning)
+def test_from_igraph_invalid_precomputed():
+    n = 100
+    m = 500
+    K = np.zeros((n, n))
+    for _ in range(m):
+        e = np.random.choice(n, 2, replace=False)
+        K[e[0], e[1]] = K[e[1], e[0]] = 1
+    g = igraph.Graph.Adjacency(K.tolist())
+    G = graphtools.from_igraph(g, precomputed='affinity')
+
+
 def test_to_pygsp():
     G = build_graph(data)
     G2 = G.to_pygsp()
     assert isinstance(G2, graphtools.graphs.PyGSPGraph)
     assert np.all(G2.K == G.K)
 
+
+@warns(UserWarning)
+def test_to_pygsp_invalid_precomputed():
+    G = build_graph(data)
+    G2 = G.to_pygsp(precomputed='adjacency')
+
+
+@warns(UserWarning)
+def test_to_pygsp_invalid_use_pygsp():
+    G = build_graph(data)
+    G2 = G.to_pygsp(use_pygsp=False)
+
 #####################################################
 # Check parameters
 #####################################################