[plotting] pd fixed bug when index is not sorted

plotting.py

@@ -117,6 +117,7 @@ def figure_history(history_csv_path):
 def plot_histories(history_csv_path, path, cut=None, roll=1):
     df = pd.read_csv(history_csv_path)
     df = df.set_index("epoch")
+    df = df.sort_index()
     df = df.truncate(after=cut)
     for col in df.columns:
         if col.startswith("val_"):