Add method `ishape_range`

Common/util_eddies.py

@@ -202,6 +202,12 @@ class SHPC_class:
 
         return ishape
 
+    def ishape_range(self, date, i_slice, orientation):
+        ishape_start = self.comp_ishape(date, 1, i_slice, orientation)
+        ishape_stop = self._ishape_last[i_slice][orientation]\
+            [date - self.d_init[i_slice]] + 1
+        return range(ishape_start, ishape_stop)
+
 def in_window(point, window):
     llcrnrlon, llcrnrlat, urcrnrlon, urcrnrlat = window
     longit = point[0] + math.ceil((llcrnrlon - point[0]) / 360) * 360