fix slicing for LabelTensor (#167)

* fix slicing for LabelTensor
* Update testing_pr.yml for solving python3.1 error

.github/workflows/testing_pr.yml

@@ -14,7 +14,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [windows-latest, macos-latest, ubuntu-latest]
-        python-version: [3.7, 3.8, 3.9, 3.10]
+        python-version: [3.7, 3.8, 3.9, '3.10']
         
     steps:
     - uses: actions/checkout@v2

pina/label_tensor.py

@@ -197,8 +197,22 @@ class LabelTensor(torch.Tensor):
         Return a copy of the selected tensor.
         """
         selected_lt = super(Tensor, self).__getitem__(index)
-        if hasattr(self, 'labels'):
-            selected_lt.labels = self.labels
+
+        try:
+            len_index = len(index)
+        except TypeError:
+            len_index = 1
+
+        if isinstance(index, int) or len_index == 1:
+            if selected_lt.ndim == 1:
+                selected_lt = selected_lt.reshape(1, -1)
+            if hasattr(self, 'labels'):
+                selected_lt.labels = self.labels
+        elif len_index == 2:
+            if selected_lt.ndim == 1:
+                selected_lt = selected_lt.reshape(-1, 1)
+            if hasattr(self, 'labels'):
+                selected_lt.labels = self.labels[index[1]]
 
         return selected_lt
 

tests/test_label_tensor.py

@@ -73,7 +73,7 @@ def test_merge():
     tensor_bc = tensor_b.append(tensor_c)
     assert torch.allclose(tensor_bc, tensor.extract(['b', 'c']))
 
-def test_merge():
+def test_merge2():
     tensor = LabelTensor(data, labels)
     tensor_b = tensor.extract('b')
     tensor_c = tensor.extract('c')
@@ -87,4 +87,18 @@ def test_getitem():
     tensor_view = tensor[:5]
 
     assert tensor_view.labels == labels
-    assert torch.allclose(tensor_view, data[:5])
+    assert torch.allclose(tensor_view, data[:5])
+
+def test_slice():
+    tensor = LabelTensor(data, labels)
+    tensor_view = tensor[:5, :2]
+    assert tensor_view.labels == labels[:2]
+    assert torch.allclose(tensor_view, data[:5, :2])
+
+    tensor_view2 = tensor[3]
+    assert tensor_view2.labels == labels
+    assert torch.allclose(tensor_view2, data[3])
+
+    tensor_view3 = tensor[:, 2]
+    assert tensor_view3.labels == labels[2]
+    assert torch.allclose(tensor_view3, data[:, 2].reshape(-1, 1))