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README.md

@@ -63,7 +63,8 @@ astar.setup(map_width, map_height, direction, allocate, typical_adjacent, cache)
 
 ### astar.set_map(world)
 
-Set your map data.
+Set your map data.  
+*Setting new map data reset the current cache.
 
 ```lua
 local world = {
@@ -83,6 +84,8 @@ Set costs for your walkable tiles on your `world` table. This table keys determi
 
 Table's sum must be the `astar.DIRECTION_FOUR` or `astar.DIRECTION_EIGHT`. In this example we want to move 8 direction. 
 
+*Setting new cost data reset the current cache.
+
 ```lua
 local costs = {
     [2] = {