fix: Graph.__str__ separates thousands in its counts

src/pgraph/PGraph.py

@@ -288,6 +288,8 @@ def __str__(self) -> str:
         :return: one-line summary of vertex/edge/component counts
         :rtype: str
 
+        Counts of 1,000 or more have thousands separators.
+
         .. runblock:: pycon
 
             >>> from pgraph import UGraph
@@ -301,7 +303,7 @@ def __str__(self) -> str:
 
         :seealso: :meth:`show`
         """
-        s = f"{self.__class__.__name__}: {self.n} {'vertex' if self.n==1 else 'vertices'}, {self.ne} edge{'s'[:self.ne^1]}, {self.nc} component{'s'[:self.nc^1]}"
+        s = f"{self.__class__.__name__}: {self.n:,} {'vertex' if self.n==1 else 'vertices'}, {self.ne:,} edge{'s'[:self.ne^1]}, {self.nc:,} component{'s'[:self.nc^1]}"
         return s
 
     def __repr__(self) -> str:

tests/test_graph.py

@@ -3,7 +3,7 @@
 import numpy as np
 import numpy.testing as nt
 
-from pgraph import *
+from pgraph import DGraph, Edge, UGraph, Vertex
 
 class TestUGraph(unittest.TestCase):
 
@@ -51,6 +51,21 @@ def test_str(self):
         self.assertEqual(len(lines), 3)  # class-name header + one line per vertex
         self.assertEqual(lines[0], "DGraph:")
 
+
+    def test_str_has_thousands_separators(self):
+        # counts of 1,000 or more are easier to read with separators
+        g = UGraph()
+        vs = [g.add_vertex() for _ in range(1001)]
+        self.assertEqual(str(g), "UGraph: 1,001 vertices, 0 edges, 1,001 components")
+        for a, b in zip(vs, vs[1:]):
+            g.add_edge(a, b)
+        self.assertEqual(str(g), "UGraph: 1,001 vertices, 1,000 edges, 1 component")
+        # below a thousand it is as before
+        h = UGraph()
+        for _ in range(999):
+            h.add_vertex()
+        self.assertEqual(str(h), "UGraph: 999 vertices, 0 edges, 999 components")
+
     def test_attr(self):
 
         g = UGraph()