From 9f95d73da658e0cf5c6096561b045cee07714497 Mon Sep 17 00:00:00 2001
From: mss <marcspeck@gmail.com>
Date: Wed, 7 Sep 2022 10:37:37 +0200
Subject: [PATCH] 'if self.tdrWindow.td' throws a ValueError when td is not
 empty

---
 NanoVNASaver/Charts/TDR.py  | 4 ++--
 NanoVNASaver/Windows/TDR.py | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/NanoVNASaver/Charts/TDR.py b/NanoVNASaver/Charts/TDR.py
index 16d80bb..2d7fc7c 100644
--- a/NanoVNASaver/Charts/TDR.py
+++ b/NanoVNASaver/Charts/TDR.py
@@ -256,7 +256,7 @@ class TDRChart(Chart):
             return
         a0.accept()
         width = self.width() - self.leftMargin - self.rightMargin
-        if len(self.tdrWindow.td) > 0:
+        if self.tdrWindow.td:
             if self.fixedSpan:
                 max_index = np.searchsorted(self.tdrWindow.distance_axis, self.maxDisplayLength * 2)
                 min_index = np.searchsorted(self.tdrWindow.distance_axis, self.minDisplayLength * 2)
@@ -415,7 +415,7 @@ class TDRChart(Chart):
         qp.end()
 
     def valueAtPosition(self, y):
-        if len(self.tdrWindow.td) > 0:
+        if self.tdrWindow.td:
             height = self.height() - self.topMargin - self.bottomMargin
             absy = (self.height() - y) - self.bottomMargin
             if self.fixedValues:
diff --git a/NanoVNASaver/Windows/TDR.py b/NanoVNASaver/Windows/TDR.py
index 7006dbe..52b7dbb 100644
--- a/NanoVNASaver/Windows/TDR.py
+++ b/NanoVNASaver/Windows/TDR.py
@@ -34,7 +34,7 @@ class TDRWindow(QtWidgets.QWidget):
         super().__init__()
         self.app = app
 
-        self.td = []
+        self.td = None
         self.distance_axis = []
         self.step_response = []
         self.step_response_Z = []