Added r as attribute to Touchstone

NanoVNASaver/Touchstone.py

@@ -113,7 +113,11 @@ class Touchstone:
     def s22data(self) -> list:
         return self.s("22")
 
-    def s(self, name: str):
+    @property
+    def r(self) -> int:
+        return self.opts.resistance
+
+    def s(self, name: str) -> list:
         return self.sdata[Touchstone.FIELD_ORDER.index(name)]
 
     def _parse_comments(self, fp) -> str:

test/test_touchstone.py

@@ -61,6 +61,7 @@ class TestTouchstoneTouchstone(unittest.TestCase):
         self.assertEqual(str(ts.opts), "# HZ S RI R 50")
         self.assertEqual(len(ts.s11data), 1010)
         self.assertEqual(len(ts.s21data), 0)
+        self.assertEqual(ts.r, 50)
 
         ts = Touchstone("./test/data/valid.s2p")
         ts.load()