MIDict (Multi-Index Dict)

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MIDict is an ordered “dictionary” with multiple indices where any index can serve as “keys” or “values”, capable of assessing multiple values via its powerful indexing syntax, and suitable as a bidirectional/inverse dict (a drop-in replacement for dict/OrderedDict in Python 2 & 3).


  • Multiple indices
  • Multi-value indexing syntax
  • Convenient indexing shortcuts
  • Bidirectional/inverse dict
  • Compatible with normal dict in Python 2 & 3
  • Accessing keys via attributes
  • Extended methods for multi-indices
  • Additional APIs to handle indices
  • Duplicate keys/values handling


name uid ip
jack 1 192.1
tony 2 192.2

The above table-like data set (with multiple columns/indices) can be represented using a MIDict:

user = MIDict([['jack', 1, '192.1'], # list of items (rows of data)
               ['tony', 2, '192.2']],
              ['name', 'uid', 'ip']) # a list of index names

Access a key and get a value or a list of values (similar to a normal dict):

user['jack'] == [1, '192.1']

Any index (column) can be used as the “keys” or “values” via the advanced “multi-indexing” syntax d[index_key:key, index_value]. Both index_key and index_value can be a normal index name or an int (the order the index), and index_value can also be a tuple, list or slice object to specify multiple values, e.g.:

user['name':'jack', 'uid'] == 1
user['ip':'192.1', 'name'] == 'jack'

user['name':'jack', ('uid', 'ip')] == [1, '192.1']
user[0:'jack', [1, 2]]             == [1, '192.1']
user['name':'jack', 'uid':]        == [1, '192.1']

The “multi-indexing” syntax also has convenient shortcuts:

user['jack'] == [1, '192.1']
user[:'192.1'] == ['jack', 1]
user['jack', :] == ['jack', 1, '192.1']

A MIDict with 2 indices can be used as a bidirectional/inverse dict:

color = MIDict(red='#FF0000', green='#00FF00')

color['red']      == '#FF0000' # forward indexing: d[key] -> value
color[:'#FF0000'] == 'red'     # backward/inverse indexing: d[:value] -> key


pip install midict

PyPI repository: https://pypi.python.org/pypi/midict


Source code: https://github.com/ShenggaoZhu/midict

Report issues: https://github.com/ShenggaoZhu/midict/issues/new


python tests/tests.py

Tested with both Python 2.7 and Python 3,3, 3.4, 3.5.

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