add util function to get most recent last.pt file

added logic in train.py __main__ to handle resuming from a run

utils/utils.py

@@ -36,6 +36,12 @@ def init_seeds(seed=0):
     np.random.seed(seed)
     torch_utils.init_seeds(seed=seed)
 
+def get_latest_run(search_dir = './runs/'):
+    # get path to most recent 'last.pt' in run dirs
+    # assumes most recently saved 'last.pt' is the desired weights to --resume from
+    last_list =  glob.glob('runs/*/last.pt')
+    latest = max(last_list, key = os.path.getctime)
+    return latest
 
 def check_git_status():
     # Suggest 'git pull' if repo is out of date