Added -c option to cmd interface to print available columns in log file

lammps_logfile/cmd_interface.py

@@ -4,24 +4,30 @@
 import matplotlib.pyplot as plt
 
 def get_parser():
-    parser = argparse.ArgumentParser(description="Plot contents from lammps log files")
+    parser = argparse.ArgumentParser(description="Plot contents from lammps log files. Input file argument comes before keyword arguments. ")
     parser.add_argument("-x", type=str, default="Time", help="Data to plot on the first axis")
     parser.add_argument("-y", type=str, nargs="+", help="Data to plot on the second axis. You can supply several names to get several plot lines in the same figure.")
     parser.add_argument("-a", "--running_average", type=int, default=1, help="Optionally average over this many log entries with a running average. Some thermo properties fluctuate wildly, and often we are interested in te running average of properties like temperature and pressure.")
     parser.add_argument("input_file",  metavar='INPUT_FILE', type=str, help="Lammps log file containing thermo output from lammps simulation.")
     parser.add_argument("-o", type=str, dest='fout', default='', help='Save the figure to this file; the format must be supported by matplotlib.')
+    parser.add_argument("-c", "--columns", action='store_true', default=False, help='Print columns of the lammps logfile')
+
     return parser
 
 def run():
     args = get_parser().parse_args()
     log = File(args.input_file)
+
+    if args.columns: 
+         print(f"Columns available in log file:\n{' '.join(log.get_keywords())}")
+         if args.y is None:
+              exit(0)
+
     x = log.get(args.x)
-    print(x)
     if args.running_average >= 2:    
             x = running_mean(x, args.running_average)
     for y in args.y:
         data = log.get(y)
-        print(data)
         if args.running_average >= 2:    
             data = running_mean(data, args.running_average)