plot_sayma_data: Add option to log phase measurements

plot_sayma_data.py

@@ -28,6 +28,9 @@ def main():
         "CHANNEL must be 1 or 2; "
         "NAME must be any of: " + " ".join(list(RP_IP_ADDRS.keys())),
         type=str, nargs=2)
+    parser.add_argument("--log",
+        help="path of the log file where the measurement record will be appended",
+        type=str)
     args = parser.parse_args()
 
     # Must only compare 2 data
@@ -65,6 +68,13 @@ def main():
     # Element-wise multiply Z[0] with the conjugate of Z[1] to get the phase difference (i.e. angle(z0) - angle(z1)), and use the mean value.
     angle = np.angle(np.mean(z[0]*z[1].conj()))
 
+    # Append the phase difference to the log file
+    log = args.log
+    if log is not None:
+        with open(log, 'a') as f:
+            f.write("{}\t{}\n".format(now_iso, angle))
+            print("Phase measurement record appended to log: {}".format(log))
+    # Print the phase difference
     print(angle)
 
     # Normalize y1 and y2 for plotting