add util function to get most recent last.pt file

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

train.py

@@ -198,10 +198,10 @@ def train(hyp):
     model.names = data_dict['names']
 
     #save hyperparamter and training options in run folder
-    with open(os.path.join(log_dir, 'hyp.yaml', 'w')) as f:
+    with open(os.path.join(log_dir, 'hyp.yaml'), 'w') as f:
         yaml.dump(hyp, f)
 
-    with open(os.path.join(log_dir, 'opt.yaml', 'w')) as f:
+    with open(os.path.join(log_dir, 'opt.yaml'), 'w') as f:
         yaml.dump(opt, f)
     
     # Class frequency
@@ -294,7 +294,7 @@ def train(hyp):
 
             # Plot
             if ni < 3:
-                f = 'train_batch%g.jpg' % i  # filename
+                f = os.path.join(log_dir, 'train_batch%g.jpg' % i)  # filename
                 res = plot_images(images=imgs, targets=targets, paths=paths, fname=f)
                 if tb_writer:
                     tb_writer.add_image(f, res, dataformats='HWC', global_step=epoch)
@@ -385,6 +385,7 @@ if __name__ == '__main__':
     parser.add_argument('--img-size', nargs='+', type=int, default=[640, 640], help='train,test sizes')
     parser.add_argument('--rect', action='store_true', help='rectangular training')
     parser.add_argument('--resume', action='store_true', help='resume training from last.pt')
+    parser.add_argument('--resume_from_run', type=str, default='', 'resume training from last.pt in this dir')
     parser.add_argument('--nosave', action='store_true', help='only save final checkpoint')
     parser.add_argument('--notest', action='store_true', help='only test final epoch')
     parser.add_argument('--evolve', action='store_true', help='evolve hyperparameters')
@@ -398,6 +399,12 @@ if __name__ == '__main__':
     parser.add_argument('--single-cls', action='store_true', help='train as single-class dataset')
     parser.add_argument('--hyp', type=str, default='', help ='path to hyp yaml file')
     opt = parser.parse_args()
+
+    if opt.resume and not opt.resume_from_run:
+        last = get_latest_run()
+        print(f'WARNING: No run provided to resume from. Resuming from most recent run found at {last}')
+    else:
+        last = opt.resume_from_run
     opt.weights = last if opt.resume else opt.weights
     opt.cfg = check_file(opt.cfg)  # check file
     opt.data = check_file(opt.data)  # check file