Fix default value for ignore_index to -100 to match with CrossEntropyLoss

Author: BloodAxe

pytorch_toolbelt/losses/soft_ce.py

@@ -6,7 +6,7 @@
 
 
 class SoftCrossEntropyLoss(nn.Module):
-    def __init__(self, smooth_factor=1e-4, ignore_index=None):
+    def __init__(self, smooth_factor=1e-4, ignore_index: int = -100):
         super().__init__()
         self.smooth_factor = smooth_factor
         self.ignore_index = ignore_index