[params] Now use default value if not in the param file

params.py

@@ -26,11 +26,18 @@ _loader.add_implicit_resolver(
 )
 
 
-def load_params(filename):
+def params_from_file(filename):
     with open(filename) as f:
         para_disk = yaml.load(f, Loader=_loader)
     return munch.munchify(para_disk)
 
 
 def default_params():
-    return load_params(_dir_path + "/params.yml")
+    return params_from_file(_dir_path + "/params.yml")
+
+
+def load_params(filename):
+    basic_params = default_params()
+    new_params = params_from_file(filename)
+    basic_params.update(new_params)
+    return basic_params