Python Code Snippet to Pretty-Print a Table of Values

def format_dict_table(rows, column_names=None, max_column_width=None, border_style=2):
    """
    Returns a string representation of a tuple of dictionaries in a
    table format. This method can read the column names directly off the
    dictionary keys, but if a tuple of these keys is provided in the
    'column_names' variable, then the order of column_names will follow
    the order of the fields/keys in that variable.
    """
    if column_names or len(rows) > 0:
        lengths = {}
        rules = {}
        if column_names:
            column_list = column_names
        else:
            try:
                column_list = rows[0].keys()
            except:
                column_list = None
        if column_list:
            # characters that make up the table rules
            border_style = int(border_style)
            #border_style = 0
            if border_style >= 1:
                vertical_rule = ' | '
                horizontal_rule = '-'
                rule_junction = '-+-'
            else:
                vertical_rule = '  '
                horizontal_rule = ''
                rule_junction = ''                
            if border_style >= 2:
                left_table_edge_rule = '| '
                right_table_edge_rule = ' |'
                left_table_edge_rule_junction = '+-'
                right_table_edge_rule_junction = '-+'
            else:
                left_table_edge_rule = ''
                right_table_edge_rule = ''
                left_table_edge_rule_junction = ''
                right_table_edge_rule_junction = ''
 
            if max_column_width:
                column_list = [c[:max_column_width] for c in column_list]
                trunc_rows = []
                for row in rows:
                    new_row = {}
                    for k in row.keys():
                        new_row[k[:max_column_width]] = str(row[k])[:max_column_width]
                    trunc_rows.append(new_row)
                rows = trunc_rows
 
            for col in column_list:
                rls = [len(str(row[col])) for row in rows]
                lengths[col] = max(rls+[len(col)])
                rules[col] = horizontal_rule*lengths[col]
 
            template_elements = ["%%(%s)-%ss" % (col, lengths[col]) for col in column_list]
            row_template = vertical_rule.join(template_elements)
            border_template = rule_junction.join(template_elements)
            full_line = left_table_edge_rule_junction + (border_template % rules) + right_table_edge_rule_junction 
            display = []
            if border_style > 0:
                display.append(full_line)
            display.append(left_table_edge_rule + (row_template % dict(zip(column_list, column_list))) + right_table_edge_rule)
            if border_style > 0:
                display.append(full_line)
            for row in rows:       
                display.append(left_table_edge_rule + (row_template % row) + right_table_edge_rule)
            if border_style > 0:        
                display.append(full_line)
            return "\n".join(display)
        else:
            return ''
    else:
        return ''