Update art/defences/detector/poison/activation_defence.py

Co-authored-by: Beat Buesser <[email protected]>

Author: keykholt

art/defences/detector/poison/activation_defence.py

@@ -671,7 +671,7 @@ def _check_params(self):
             raise ValueError("Unsupported method for cluster analysis method: " + self.cluster_analysis)
         if self.generator and not isinstance(self.generator, DataGenerator):
             raise TypeError("Generator must a an instance of DataGenerator")
-        if self.ex_re_threshold and self.ex_re_threshold <= 0:
+        if self.ex_re_threshold is not None and self.ex_re_threshold <= 0:
             raise ValueError("Exclusionary reclassification threshold must be positive")
 
     def _get_activations(self, x_train: Optional[np.ndarray] = None) -> np.ndarray: