diff --git a/run_selector.py b/run_selector.py
index 80c1877..a1e7e6f 100644
--- a/run_selector.py
+++ b/run_selector.py
@@ -51,6 +51,7 @@ class RunSelector:
         time_max=None,
         time=None,
         unit_time=None,
+        allow_nodata=False,
     ):
         """
         Select runs and outputs with several filter options.
@@ -84,6 +85,7 @@ class RunSelector:
             time_max    : float, select output where time <= time_min (in code units)
             time        : float or list of float. For each value, select the output closer to it.
             unit_time   : astrophysix.Unit, unit for the time above. None is code unit.
+            allow_nodata : allow runs whith only postprocessed datas
 
             3. Sort the runs
 
@@ -97,6 +99,8 @@ class RunSelector:
         self.namelist = {}
         self.runs = self.get_runs(in_runs, filter_name, filter_nml, sort_run_by)
 
+        self.allow_nodata = allow_nodata
+
         self.info = {}
         for run in self.runs:
             self.info[run] = {}
@@ -281,8 +285,10 @@ class RunSelector:
         info_filename_folder = f"{self.path_in}/{run}/info/info_{num:05}.txt"
         if os.path.exists(info_filename_output):
             info = read_ramses_info_file(info_filename_output)
-        else:
+        elif self.allow_nodata:
             info = read_ramses_info_file(info_filename_folder)
+        else:
+            raise IOError
         return info
 
     def get_nums(
@@ -336,10 +342,16 @@ class RunSelector:
             def get_time(num):
                 return self.info[run][num]["time"]
 
-        else:
-
+        elif isinstance(unit_time, str):
+            
+            factor = self.get_nml_value(unit_time, run)
             def get_time(num):
-                time_code = self.info[run][num]["time"]
+                time_code = self.info[run][num]["time"]     
+                return time_code / factor
+
+        else:
+            def get_time(num):
+                time_code = self.info[run][num]["time"]     
                 return time_code * self.info[run][num]["unit_time"].express(unit_time)
 
         # -- A function to search a given time using dichotomy
@@ -466,7 +478,7 @@ class RunSelector:
             prefix = self.path_in 
         paths = []
         for run in self.nums:
-            for num in nums[run]:
+            for num in self.nums[run]:
                 paths.append(f"{prefix}/{run}/output_{num:05}\n")
         f = open(os.path.expanduser(filename), "w")
         f.writelines(paths)