diff --git a/lang/zh/gklearn/ged/edit_costs/constant.py b/lang/zh/gklearn/ged/edit_costs/constant.py
new file mode 100644
index 0000000..641bab7
--- /dev/null
+++ b/lang/zh/gklearn/ged/edit_costs/constant.py
@@ -0,0 +1,50 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""
+Created on Wed Jun 17 17:52:23 2020
+
+@author: ljia
+"""
+from gklearn.ged.edit_costs import EditCost
+
+
+class Constant(EditCost):
+	"""Implements constant edit cost functions.
+	"""
+
+	
+	def __init__(self, node_ins_cost=1, node_del_cost=1, node_rel_cost=1, edge_ins_cost=1, edge_del_cost=1, edge_rel_cost=1):
+		self.__node_ins_cost = node_ins_cost
+		self.__node_del_cost = node_del_cost
+		self.__node_rel_cost = node_rel_cost
+		self.__edge_ins_cost = edge_ins_cost
+		self.__edge_del_cost = edge_del_cost
+		self.__edge_rel_cost = edge_rel_cost
+		
+		
+	def node_ins_cost_fun(self, node_label):
+		return self.__node_ins_cost
+	
+	
+	def node_del_cost_fun(self, node_label):
+		return self.__node_del_cost
+	
+	
+	def node_rel_cost_fun(self, node_label_1, node_label_2):
+		if node_label_1 != node_label_2:
+			return self.__node_rel_cost
+		return 0
+	
+	
+	def edge_ins_cost_fun(self, edge_label):
+		return self.__edge_ins_cost
+	
+	
+	def edge_del_cost_fun(self, edge_label):
+		return self.__edge_del_cost
+	
+	
+	def edge_rel_cost_fun(self, edge_label_1, edge_label_2):
+		if edge_label_1 != edge_label_2:
+			return self.__edge_rel_cost
+		return 0
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