Introduction

This Python package provide a function flatten() for flattening dict-like objects. It also provides some key joining methods (reducer), and you can choose the reducer you want or even implement your own reducer. You can also choose to invert the resulting flat dict.

Documentation

def flatten(d, reducer='tuple', inverse=False):
    """Flatten dict-like object.

    Parameters
    ----------
    d: dict-like object
        The dict that will be flattened.
    reducer: {'tuple', 'path', function} (default: 'tuple')
        The key joining method. If a function is given, the function will be
        used to reduce.
        'tuple': The resulting key will be tuple of the original keys
        'path': Use ``os.path.join`` to join keys.
    inverse: bool (default: False)
        Whether you want invert the resulting key and value.

    Returns
    -------
    flat_dict: dict
    """

Examples

In [1]: from flatten_dict import flatten

In [2]: normal_dict = {
   ...:     'a': '0',
   ...:     'b': {
   ...:         'a': '1.0',
   ...:         'b': '1.1',
   ...:     },
   ...:     'c': {
   ...:         'a': '2.0',
   ...:         'b': {
   ...:             'a': '2.1.0',
   ...:             'b': '2.1.1',
   ...:         },
   ...:     },
   ...: }

In [3]: flatten(normal_dict)
Out[3]:
{('a',): '0',
 ('b', 'a'): '1.0',
 ('b', 'b'): '1.1',
 ('c', 'a'): '2.0',
 ('c', 'b', 'a'): '2.1.0',
 ('c', 'b', 'b'): '2.1.1'}

In [4]: flatten(normal_dict, reducer='path')
Out[4]:
{'a': '0',
 'b/a': '1.0',
 'b/b': '1.1',
 'c/a': '2.0',
 'c/b/a': '2.1.0',
 'c/b/b': '2.1.1'}

In [5]: flatten(normal_dict, reducer='path', inverse=True)
Out[5]:
{'0': 'a',
 '1.0': 'b/a',
 '1.1': 'b/b',
 '2.0': 'c/a',
 '2.1.0': 'c/b/a',
 '2.1.1': 'c/b/b'}

In [6]: def underscore_reducer(k1, k2):
   ...:     if k1 is None:
   ...:         return k2
   ...:     else:
   ...:         return k1 + "_" + k2
   ...:

In [7]: flatten(normal_dict, reducer=underscore_reducer)
Out[7]:
{'a': '0',
 'b_a': '1.0',
 'b_b': '1.1',
 'c_a': '2.0',
 'c_b_a': '2.1.0',
 'c_b_b': '2.1.1'}