add loss check in check.py (#72)

* add loss check

pdseg/check.py

@@ -426,6 +426,15 @@ def max_img_size_statistics():
     logger.info("max width and max height of images are ({},{})".format(
         max_width, max_height))
 
+def num_classes_loss_matching_check():
+    loss_type = cfg.SOLVER.LOSS
+    num_classes = cfg.DATASET.NUM_CLASSES
+    if num_classes > 2 and (("dice_loss" in loss_type) or ("bce_loss" in loss_type)):
+        logger.info(error_print("loss check."
+            " Dice loss and bce loss is only applicable to binary classfication"))
+    else:
+        logger.info(correct_print("loss check"))
+
 
 def check_train_dataset():
     list_file = cfg.DATASET.TRAIN_FILE_LIST
@@ -474,6 +483,7 @@ def check_train_dataset():
         image_type_check(img_dim)
         max_img_size_statistics()
         shape_check()
+        num_classes_loss_matching_check()
 
 
 def check_val_dataset():