def parse_meta(self, selected_meta_data):
        """
        Parses all of the metadata files
        :param selected_meta_data: if specified then only the columns that are contained here are going to be parsed
        :return:
        """
        # reads all meta data files
        files = self._get_files("meta", self.path)
        df = pd.DataFrame()
        print("Parsing the metadata files...")
        for f in tqdm(files):
            data = self.parse_single_meta(f, selected_meta_data)
            if data is not None:
                df = pd.concat([df, data], axis=0)
        df.index = df['sample']
        #
        # df = df.drop('sample', 1)  # 1 for the columns
        return df