tools and fixes

bind/.gitignore

@@ -1 +1,2 @@
-minicalo.cpython-38-x86_64-linux-gnu.so
+minicalo.cpython-38-x86_64-linux-gnu.so
+tmp_test*

bind/G4Calo.py

@@ -397,4 +397,9 @@ def display_event(gd : GeometryDescriptor,
     if renderer is not None:
         fig.show(renderer=renderer) 
     else:
-        fig.show() 
+        fig.show() 
+
+
+
+def to_numpy(df_column):
+    return np.array(df_column.tolist())