model_devi_clean_traj support int type (#583)

* model_devi_clean_traj support buffer

* fix clean index

* update readme

Author: KZHIWEI

README.md

@@ -557,7 +557,7 @@ The bold notation of key (such aas **type_map**) means that it's a necessary key
 | model_devi_perc_candi_f  | Float | 0.0 | See `model_devi_adapt_trust_lo`.|
 | model_devi_perc_candi_v  | Float | 0.0 | See `model_devi_adapt_trust_lo`.|
 | model_devi_f_avg_relative | Boolean | False | Normalized the force model deviations by the RMS force magnitude along the trajectory. This key should not be used with `use_relative`. |
-| **model_devi_clean_traj**  | Boolean | true                                                         | Deciding whether to clean traj folders in MD since they are too large. |
+| **model_devi_clean_traj**  | Boolean or Int | true                                                         | If type of model_devi_clean_traj is boolean type then it denote whether to clean traj folders in MD since they are too large. If it is Int type, then the most recent n iterations of traj folders will be retained, others will be removed. |
 | **model_devi_nopbc**  | Boolean | False                                                         | Assume open boundary condition in MD simulations. |
 | model_devi_activation_func | List of list of string | [["tanh","tanh"],["tanh","gelu"],["gelu","tanh"],["gelu","gelu"]]	| Set activation functions for models, length of the List should be the same as `numb_models`, and two elements in the list of string respectively assign activation functions to the embedding and fitting nets within each model. *Backward compatibility*: the orginal "List of String" format is still supported, where embedding and fitting nets of one model use the same activation function, and the length of the List should be the same as `numb_models`|
 | **model_devi_jobs**        | [<br/>{<br/>"sys_idx": [0], <br/>"temps": <br/>[100],<br/>"press":<br/>[1],<br/>"trj_freq":<br/>10,<br/>"nsteps":<br/> 1000,<br/> "ensembles": <br/> "nvt" <br />},<br />...<br />] | List of dict | Settings for exploration in `01.model_devi`. Each dict in the list corresponds to one iteration. The index of `model_devi_jobs` exactly accord with index of iterations |

dpgen/generator/run.py

@@ -2840,15 +2840,24 @@ def post_fp (iter_index,
     else :
         raise RuntimeError ("unsupported fp style")
     # clean traj
-    iter_name = make_iter_name(iter_index)
     clean_traj = True
     if 'model_devi_clean_traj' in jdata :
         clean_traj = jdata['model_devi_clean_traj']
-    if clean_traj:
-        modd_path = os.path.join(iter_name, model_devi_name)
+    modd_path =  None
+    if isinstance(clean_traj, bool):
+        iter_name = make_iter_name(iter_index)
+        if clean_traj:
+            modd_path = os.path.join(iter_name, model_devi_name)
+    elif isinstance(clean_traj, int):
+        clean_index = iter_index - clean_traj
+        if clean_index >= 0:
+            modd_path = os.path.join(make_iter_name(clean_index), model_devi_name)
+    if modd_path is not None:
         md_trajs = glob.glob(os.path.join(modd_path, 'task*/traj'))
-        for ii in md_trajs :
+        for ii in md_trajs:
             shutil.rmtree(ii)
+        
+
 
 def set_version(mdata):