fix old codes

pina/label_tensor.py

@@ -55,6 +55,8 @@ class LabelTensor(torch.Tensor):
                     [0.9518, 0.1025],
                     [0.8066, 0.9615]])
         '''
+        if x.ndim == 1:
+            x = x.reshape(-1, 1)
 
         if isinstance(labels, str):
             labels = [labels]
@@ -130,3 +132,8 @@ class LabelTensor(torch.Tensor):
         new_labels = self.labels + lt.labels
         new_tensor = torch.cat((self, lt), dim=1)
         return LabelTensor(new_tensor, new_labels)
+
+    def __str__(self):
+        s = f'labels({str(self.labels)})\n'
+        s += super().__str__()
+        return s