Added a few metrics for measuring performance

spatz/metrics/metric.py

@@ -1,14 +1,19 @@
+from abc import abstractmethod
 
-
+from numpy.typing import ArrayLike
 from typing import Any
 
 
 class Metric:
     def __init__(self) -> None:
-        self.__sum = 0
+        self._score = None
 
-    def get_score():
-        pass
+    def get_score(self):
+        return self._score
 
-    def __call__(self, *args) -> Any:
-        self.__sum += abs(x - y)
+    @abstractmethod
+    def _update(self, x: ArrayLike, y: ArrayLike):
+        raise NotImplementedError()
+
+    def __call__(self, x: ArrayLike, y: ArrayLike) -> Any:
+        self._update(x, y)