first commit

helix/constants/exposure_category.py

@@ -0,0 +1,34 @@
+from enum import Enum
+
+
+class ExposureCategory(Enum):
+    B = 'B'
+    C = 'C'
+    D = 'D'
+    B_C = 'B to C'
+    C_B = 'C to B'
+
+    def z_g(self):
+        return {
+            ExposureCategory.B: 1200.,
+            ExposureCategory.C: 900.,
+            ExposureCategory.D: 700.,
+            ExposureCategory.B_C: (1273., 906.),
+            ExposureCategory.C_B: (906., 1273.)
+        }[self]
+
+    def alpha(self):
+        return {
+            ExposureCategory.B: 7.,
+            ExposureCategory.C: 9.5,
+            ExposureCategory.D: 11.5,
+            ExposureCategory.B_C: (6.62, 9.5),
+            ExposureCategory.C_B: (9.5, 6.62)
+        }[self]
+
+    def is_interpolated(self):
+        return self in [ExposureCategory.B_C, ExposureCategory.C_B]
+
+    @classmethod
+    def default_value(cls):
+        return cls.C.value