Make filename argument

eclipswaarneming.py

@@ -12,6 +12,7 @@ import time
 import matplotlib.pyplot as plt
 import datetime
 import sys
+import os.path
 import zmq
 import struct
 import pandas as pd
@@ -72,7 +73,7 @@ file_cal_times = []
 file_caldata = []
 starttime = Time.now() + 2 * u.hour
 
-if len(sys.argv) > 1:
+if len(sys.argv) > 1 and os.path.isfile(sys.argv[1]):
     df = pd.read_csv(sys.argv[1], parse_dates=[0])
     is_data = (df["tracker"] == 'suntracker') & \
               (df["offset az (deg)"] < 0.01) & \
@@ -96,10 +97,16 @@ if starttime < eclipse_endtime < starttime + 3*u.hour:
     ax.axvline(eclipse_endtime.datetime, linestyle='--', linewidth=1, color='lightgrey')
     ax.text(eclipse_endtime.datetime,0.1,'Einde: '+eclipse_endtime.isot[11:16],rotation=90, color='black', transform=ax.get_xaxis_transform())
 
-if len(sys.argv) == 1:
-    datafile = open(f"data{int(Time.now().unix)}.txt", "w")
+if len(sys.argv) == 1 or not(os.path.isfile(sys.argv[1])):
+    # Create new file
+    if len(sys.argv) == 1:
+        datafilename = f"data{int(Time.now().unix)}.txt"
+    else:
+        datafilename = sys.argv[1]
+    datafile = open(datafilename, "w")
     print("time (UTC),tracker,offset az (deg),offset el (deg),azimuth from north (deg),elevation (deg),signal", file=datafile)
 else:
+    # Append to existing file
     datafile = open(f"{sys.argv[1]}", "a")
 
 while True: