def pockettopo2compass(txtfilename, exclude_splays=False, calculate_lrud=False):
    """Main function which converts a PocketTopo .TXT file to a Compass .DAT file"""
    print 'Converting PocketTopo data file %s ...' % txtfilename

    # Read our PocketTopo .TXT file, averaging triple-shots in the process
    infile = pockettopo.TxtFile.read(txtfilename, merge_duplicate_shots=True)

    cave_name = os.path.basename(txtfilename).rsplit('.', 1)[0].replace('_', ' ')
    outfilename = txtfilename.rsplit('.', 1)[0] + '.DAT'

    # Create the Compass DatFile in memory and start building, we'll write to file when done
    outfile = compass.DatFile(cave_name)

    for insurvey in infile:
        # Our Compass and PocketTopo Surveys are very similar...
        outsurvey = compass.Survey(
            insurvey.name, insurvey.date, comment=insurvey.comment, cave_name=cave_name, declination=insurvey.declination
        )
        outsurvey.length_units = 'M'
        outsurvey.passage_units = 'M'
        
        for inshot in insurvey:
            if inshot.is_splay and exclude_splays:
                continue  # skip

            # ...but the Shot data fields require some tweaking, see `shot2shot()` for details
            outshot = shot2shot(insurvey, inshot, calculate_lrud)
            outsurvey.add_shot(outshot)

        outfile.add_survey(outsurvey)

        # DEBUG
        #for station, splays in list(insurvey.splays.items()):
        #    print 'sta %s has %d splays' % (station, len(splays))

    # Finally all built, dump the whole DatFile/Surveys/Shots structure to file
    outfile.write(outfilename)
    print 'Wrote Compass data file %s .' % outfilename
Main function which converts a PocketTopo .TXT file to a Compass .DAT file