[Feature] add positive negative statistics (#2984)

Co-authored-by: zhjwy9343 <6593865@qq.com>
Co-authored-by: Jinjing Zhou <VoVAllen@users.noreply.github.com>

python/dgl/data/fakenews.py

@@ -37,7 +37,9 @@ class FakeNewsDataset(DGLBuiltinDataset):
         - Graphs: 314
         - Nodes: 41,054
         - Edges: 40,740
-        - Number of Classes: 2
+        - Classes:
+            Fake: 157
+            Real: 157
         - Node feature size:
             bert: 768
             content: 310
@@ -49,7 +51,9 @@ class FakeNewsDataset(DGLBuiltinDataset):
         - Graphs: 5464
         - Nodes: 314,262
         - Edges: 308,798
-        - Number of Classes: 2
+        - Classes:
+            Fake: 2732
+            Real: 2732
         - Node feature size:
             bert: 768
             content: 310

python/dgl/data/fraud.py

@@ -222,13 +222,16 @@ class FraudYelpDataset(FraudDataset):
 
     Statistics:
 
-    - Nodes: 45954
+    - Nodes: 45,954
     - Edges:
         R-U-R: 49,315
         R-T-R: 573,616
         R-S-R: 3,402,743
         ALL: 3,846,979
-    - Number of Classes: 2
+    - Classes:
+        Positive (spam): 6,677
+        Negative (legitimate): 39,277
+    - Positive-Negative ratio: 1 : 5.9
     - Node feature size: 32
 
     Parameters
@@ -285,13 +288,16 @@ class FraudAmazonDataset(FraudDataset):
 
     Statistics:
 
-    - Nodes: 11944
+    - Nodes: 11,944
     - Edges:
         U-P-U: 175,608
         U-S-U: 3,566,479
         U-V-U: 1,036,737
         ALL: 4,398,392
-    - Number of Classes: 2
+    - Classes:
+        Positive (fraudulent): 821
+        Negative (benign): 11,123
+    - Positive-Negative ratio: 1 : 13.5
     - Node feature size: 25
 
     Parameters