utils.py 文件源码

def flatten_dict(d, parent_key='', sep='_'):
    """Flattens a nested dictionary.

    :param d: A nested dictionary
    :type d: dict or MutableMapping
    :param str parent_key: The parent's key. This is a value for tail recursion, so don't set it yourself.
    :param str sep: The separator used between dictionary levels

    .. seealso:: http://stackoverflow.com/a/6027615
    """
    items = []
    for k, v in d.items():
        new_key = parent_key + sep + k if parent_key else k
        if isinstance(v, (dict, MutableMapping)):
            items.extend(flatten_dict(v, new_key, sep=sep).items())
        elif isinstance(v, (set, list)):
            items.append((new_key, ','.join(v)))
        else:
            items.append((new_key, v))
    return dict(items)