Aggregate all reports of the same type into a master report

def aggregate(self):
        """
        Aggregate all reports of the same type into a master report
        """
        for report in self.reportset:
            printtime('Processing {}'.format(report.split('.')[0]), self.start)
            # Initialise the header for each report - MLST is different, as the header is different for each
            # MLST scheme. This provides a generic header instead
            header = '' if report != 'mlst.csv' else 'Strain,Genus,SequenceType,Matches,1,2,3,4,5,6,7\n'
            # Initialise a string to hold the data for each report
            data = ''
            # Open the aggregated report
            with open(os.path.join(self.reportpath, report), 'w') as aggregate:
                for sample in self.runmetadata.samples:
                    # Try to open the report for this run
                    try:
                        #
                        with open(os.path.join(sample.general.reportpath, report), 'r') as runreport:
                            # Only get the header from the first file
                            if not header:
                                header = runreport.readline()
                            else:
                                for row in runreport:
                                    # The final entry in a report does not have a newline character. Add \n as required
                                    if not row.endswith('\n'):
                                        row += '\n'
                                    # For certain reports, the header row is printed above each strain - ignore multiple
                                    # instances of the header
                                    if row.split(',')[0] != header.split(',')[0]:
                                        # Add the row to the string of data
                                        data += row
                    except IOError:
                        pass
                # Write the strings to the aggregate report file
                aggregate.write(header)
                aggregate.write(data)