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A dictionary that is indexed by insertion order.

Project Description


indexed.IndexedOrderedDict is fully compatible with collections.OrderedDict and can be used as a drop in replacement. The main difference is that key, value and item views support accessing elements by their index.

d = indexed.IndexedOrderedDict()
d["first-key"] = "first-value"
d["second-key"] = "second-value"
d["third-key"] = "third-value"

values = d.values()
assert values[2] == "third-value"

assert d.keys().index("second-key") == 1


  • Can be used with both Python 2 and 3. Provides keysview(), valuesview() and itemsview() which were removed from Python 3 for compability.
  • Access keys, values and items by index, e.g. d.keys()[5].
  • Find the index of a key, e.g. d.keys().index("key").

Excluding those additions the API is the same as the API of collections.OrderedDict(). Including:

  • Initializing, setting, getting and deleting items
  • Iterating forwards and in reverse
  • d.clear()
  • d.popitem(last=True)
  • d.move_to_end(key, last=True)
  • d.keys(), d.values(), d.items()
  • d.pop(key[, default])
  • d.setdefault(key, default=None)
  • String representation
  • Pickling
  • Copying
  • Creating from keys
  • Comparing order sensitively with other ordered dictionaries or order insensitively with standard mappings


The only dependencies are Python >= 2.7 or Python >= 3.0.

  • With pip:

    sudo pip install
  • With easy_install:

    sudo easy_install
  • From current source code:

    python build
    sudo python install


Performance is practically on the same order of magnitude as the built in collections.OrderedDict.

d collections.OrderedDict indexed.IndexedOrderedDict
Operation Avergage Worst case Average Worst case
d.copy() O(n) O(n) O(n) O(n)
d[key] O(1) O(n) O(1) O(n)
d[key] = value O(1) O(n) [1] O(1) O(n) [1]
del d[key] O(1) O(n) O(n) O(n)
d.keys()[i] O(n) [2] O(n) [2] O(1) O(1)
d.values()[i] O(n) [3] O(n) [3] O(1) O(n)
d.items()[i] O(n) [3] O(n) [3] O(1) O(n)
d.keys().index(x) O(n) [3] O(n) [3] O(n) O(n)
[1](1, 2) These are amortized worst case runtimes.
[2](1, 2) This does not work in Python 3 because colections.KeysView is not indexable. One of the theoretically best work arounds is next(itertools.islice(d.keys(), i, i + 1)).
[3](1, 2, 3, 4, 5, 6) Assuming the theoretically best possible workaround.

License is licensed under the GPL3. See the LICENSE file for full copyright and license information.

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