Improve log download: remove empty records, sort by timestamp

To make Plotjuggler not to warn about unsorted records everytime

tools/grab_log.py

@@ -9,8 +9,7 @@ PORT = os.environ['PORT']
 DIR = os.path.dirname(os.path.realpath(__file__))
 
 dev = serial.Serial(port=PORT, baudrate=115200, timeout=0.5)
-
-log = open(f'{DIR}/log/{datetime.datetime.now().isoformat()}.csv', 'wb')
+lines = []
 
 print('Downloading log...')
 count = 0
@@ -19,8 +18,14 @@ while True:
     line = dev.readline()
     if not line:
         break
-    log.write(line)
+    lines.append(line)
     count += 1
     print(f'\r{count} lines', end='')
 
+# sort by timestamp
+header = lines.pop(0)
+lines.sort(key=lambda line: float(line.split(b',')[0]))
+
+log = open(f'{DIR}/log/{datetime.datetime.now().isoformat()}.csv', 'wb')
+log.writelines([header] + lines)
 print(f'\nWritten {os.path.relpath(log.name, os.curdir)}')