Update preprocessing.py

MARBLE/preprocessing.py

@@ -65,7 +65,7 @@ def construct_dataset(
     for i, (a, v, l, m) in enumerate(zip(anchor, vector, label, mask)):
         for _ in range(number_of_resamples):
             # even sampling of points
-            start_idx is None:
+            if start_idx is None:
                 start_idx = torch.randint(low=0, high=len(a), size=(1,))
             sample_ind, _ = g.furthest_point_sampling(a, spacing=spacing, start_idx=start_idx)
             sample_ind, _ = torch.sort(sample_ind) #this will make postprocessing easier