fix input format conversion

ece.py

@@ -110,13 +110,13 @@ class ECE(evaluate.Metric):
 
         # Determine number of classes / binary or multiclass
         binary = True
-        if "num_classes" not in kwargs:
-            max_label = int(amax(references, list(range(references.dim()))))
-            if max_label > 1:
-                kwargs["num_classes"] = max_label
-                binary = False
-        elif kwargs["num_classes"] > 1:
+        if predictions.dim() == references.dim() + 1:
             binary = False
+            if "num_classes" not in kwargs:
+                kwargs["num_classes"] = int(predictions.shape[1])
+        else:
+            raise ValueError("Bad input shape. Expected to have predictions with shape (N,C,...) and references"
+                             f"with shape (N,...), but got {predictions.shape} and {references.shape}")
 
         # Compute the calibration
         if binary: