Refactor Feature chaining and add test case for Feature chain with la…

…mbda (#206)

deeptrack/features.py

@@ -508,7 +508,7 @@ def __iter__(self):
     def __next__(self):
         yield self.update().resolve()
 
-    def __rshift__(self, other: "Feature") -> "Feature":
+    def __rshift__(self, other) -> "Feature":
 
         # Allows chaining of features. For example,
         # feature1 >> feature2 >> feature3
@@ -519,12 +519,11 @@ def __rshift__(self, other: "Feature") -> "Feature":
             return Chain(self, other)
 
         # Import here to avoid circular import.
-        from . import models
+
 
         # If other is a function, call it on the output of the feature.
         # For example, feature >> some_function
-        if isinstance(other, models.KerasModel):
-            return NotImplemented
+
         if callable(other):
             return self >> Lambda(lambda: other)
 

deeptrack/test/test_features.py

@@ -458,6 +458,18 @@ def test_Feature_arithmetic(self):
         input_2 = [10, 20]
         self.assertListEqual(pipeline(input_2), [-input_2[0], -input_2[1]])
 
+    def test_Features_chain_lambda(self):
+
+        value = features.Value(value=1)
+        func = lambda x: x + 1
+
+        feature = value >> func
+        feature.store_properties()
+
+        feature.update()
+        output_image = feature()
+        self.assertEqual(output_image, 2)
+
     def test_Feature_repeat(self):
         feature = features.Value(value=0) >> (features.Add(1) ^ iter(range(10)))