work on get friction values from rk

src/Model/Friction/Friction.py

@@ -22,6 +22,8 @@ from tools import trace, timer
 
 from Model.Tools.PamhyrDB import SQLSubModel
 
+from numpy import interp
+
 logger = logging.getLogger()
 
 
@@ -241,3 +243,17 @@ class Friction(SQLSubModel):
     def end_strickler(self, strickler):
         self._end_strickler = strickler
         self._status.modified()
+
+    def get_friction(self, rk):
+        if not self.contains_rk(rk):
+            return None
+        minor = interp(rk,
+                       [self.begin_rk, self.end_rk],
+                       [self.begin_strickler.minor,
+                        self.end_strickler.minor])
+        medium = interp(rk,
+                        [self.begin_rk, self.end_rk],
+                        [self.begin_strickler.medium,
+                         self.end_strickler.medium])
+
+        return minor, medium