creates a map file (in the standard CSV format) based on 
        columns of a dataset. 
        1. read column names, lookup names in list
        2. read column content, get highest match of distinct values 
            from ontology lists (eg, Years, countries, cities, ages)

def generate_map_from_dataset(self, l_dataset):
        """
        creates a map file (in the standard CSV format) based on 
        columns of a dataset. 
        1. read column names, lookup names in list
        2. read column content, get highest match of distinct values 
            from ontology lists (eg, Years, countries, cities, ages)
        """
        l_map = []
        headers = l_dataset.get_header()
        print(headers)
        for row_num, col in enumerate(headers):
            if col != '':
                l_map.append('column:name:' + str(row_num) + '=' + l_dataset.force_to_string(col))
        
        for row_num, col in enumerate(headers):
            if col != '':
                vals = l_dataset.get_distinct_values_from_cols([col])
                l_map.append('column:count:distinct:' + col + '=' + str(len(vals[0])) )
                
        for row_num, col in enumerate(headers):
            if col != '':
                col_vals = l_dataset.count_unique_values(row_num, col, 10)
                for val_num, v in enumerate(col_vals):
                    l_map.append('column:topvalues:' + col + ':' + str(val_num) + '='  + v )
                #l_map.append('column:values:top5:' + str(row_num) + '=' + col_vals)
                
                
        return l_map