diff --git a/AIMSim/ops/descriptor.py b/AIMSim/ops/descriptor.py
index d25f4886..4b382c53 100644
--- a/AIMSim/ops/descriptor.py
+++ b/AIMSim/ops/descriptor.py
@@ -64,7 +64,7 @@ def to_numpy(self):
         if not hasattr(self, "numpy_"):
             self.numpy_ = np.zeros((0,), dtype=np.int8)
             DataStructs.ConvertToNumpyArray(self.rdkit_, self.numpy_)
-        self.numpy_ = self.numpy_.flatten()
+        self.numpy_ = self.numpy_.ravel()
         return self.numpy_
 
     def to_rdkit(self):
@@ -81,9 +81,7 @@ def to_rdkit(self):
         return self.rdkit_
 
     def check_init(self):
-        if hasattr(self, "numpy_") or hasattr(self, "rdkit_"):
-            return True
-        return False
+        return getattr(self, "numpy_", None) is not None or getattr(self, "rdkit_", None) is not None
 
     def _set_morgan_fingerprint(self, molecule_graph, radius, n_bits, **kwargs):
         """Set the descriptor to a morgan fingerprint.
diff --git a/AIMSim/ops/similarity_measures.py b/AIMSim/ops/similarity_measures.py
index c469c401..6e319418 100644
--- a/AIMSim/ops/similarity_measures.py
+++ b/AIMSim/ops/similarity_measures.py
@@ -252,8 +252,7 @@ def __call__(self, mol1_descriptor, mol2_descriptor):
         Returns:
             similarity_ (float): Similarity value
         """
-        if sum(mol1_descriptor.to_numpy()) == 0 \
-                or sum(mol1_descriptor.to_numpy()) == 0:
+        if not np.any(mol1_descriptor.to_numpy()) or not np.any(mol2_descriptor.to_numpy()):
             raise ValueError('Molecule descriptor has no active bits')
         similarity_ = None
         if self.metric == "l0_similarity":