Resolve "Introduce a function to return the expected average number of stories for a taxonomy string"

Closes #8 (closed)

\approve @gislars @laurens

taxonomylib/taxonomylib.py

@@ -251,3 +251,45 @@ class Taxonomy:
             self._taxonomy_dict[section] = content
         else:
             raise ValueError("Taxonomy section does not exist")
+
+    def get_number_of_stories(self):
+        """
+        Gets the number of stories as defined in the taxonomy dictionary. The function returns
+        the exact number of stories if possible or a best estimate average number based on the
+        given range of stories in the taxonomy string. Additionally, the minimum and maximum
+        values are returned (same as number of stories if exactly defined, and `None` for the
+        maximum if not defined in the taxonomy dictionary).
+
+        Returns:
+            A tuple containing the number of stories, the minimum number of stories and the
+            maximum number of stories.
+        """
+
+        try:
+            section = self.get_section("height")
+        except ValueError:
+            return None, None, None
+
+        key, value = section.split(":")
+        if key == "HBET":
+            values = value.split("-")
+            if values[0] == "":
+                min_stories = 1
+            else:
+                min_stories = int(values[0])
+                if min_stories < 1:
+                    raise ValueError("Building cannot have fewer than 1 story")
+            if values[1] == "":
+                max_stories = None
+                num_stories = min_stories + 1
+            else:
+                max_stories = int(values[1])
+                num_stories = (min_stories + max_stories) / 2
+        elif key == "H" or key == "HEX":
+            num_stories = int(value)
+            min_stories = num_stories
+            max_stories = num_stories
+        else:
+            raise ValueError("Unknown height tag in taxonomy string")
+
+        return num_stories, min_stories, max_stories