Add clear() function to class SimRandom (#401)

* Add SimRandom.clear()

* Minor

* Remove commented codes

* Lint error

maro/data_lib/cim/utils.py

@@ -5,20 +5,13 @@
 from typing import List, Union
 
 # we keep 4 random generator to make the result is reproduce-able with same seed(s), no matter if agent passed actions
-from maro.simulator.utils import random
-
 ORDER_INIT_RAND_KEY = "order_init"
 ROUTE_INIT_RAND_KEY = "route_init"
 ORDER_NUM_RAND_KEY = "order_number"
 BUFFER_TICK_RAND_KEY = "buffer_time"
 
 DATA_CONTAINER_INIT_SEED_LIMIT = 4096
 
-random.create_instance(ORDER_INIT_RAND_KEY)
-random.create_instance(ROUTE_INIT_RAND_KEY)
-random.create_instance(ORDER_NUM_RAND_KEY)
-random.create_instance(BUFFER_TICK_RAND_KEY)
-
 
 def clip(min_val: Union[int, float], max_val: Union[int, float], value: Union[int, float]) -> Union[int, float]:
     """Clip value between specified range

maro/simulator/utils/sim_random.py

@@ -86,6 +86,13 @@ def reset_seed(self, key: str) -> None:
         rand = self._rand_instances[key]
         rand.seed(self._seed_dict[key])
 
+    def clear(self) -> None:
+        """Clear all existing random keys.
+        """
+        self._rand_instances = OrderedDict()
+        self._seed_dict = {}
+        self._seed = int(time.time())
+
 
 random = SimRandom()
 """Random utility for simulator, same with original random module."""

tests/cim/test_cim_scenario.py

@@ -8,6 +8,8 @@
 
 import yaml
 
+from maro.simulator.utils import random
+
 os.environ["MARO_STREAMIT_ENABLED"] = "true"
 os.environ["MARO_STREAMIT_EXPERIMENT_NAME"] = "cim_testing"
 
@@ -37,6 +39,8 @@ def __init__(self, *args, **kwargs):
         self._reload_topology: str = TOPOLOGY_PATH_CONFIG
         self._business_engine: Optional[CimBusinessEngine] = None
 
+        random.clear()
+
     def _init_env(self, backend_name: str) -> None:
         os.environ["DEFAULT_BACKEND_NAME"] = backend_name
         self._env = Env(