This is a Python library which provides a dict-like structure which keeps elements sorted by value and maintains only the top or bottom N elements. It provides a memory efficient way of storing only the highest or lowest elements.
You can install the library using pip:
.. code-block:: bash
$ pip install limited_dict
You can create the dict-like structure as follows:
.. code:: python
from limited_dict import LimitedDict
my_dict = LimitedDict(max_length=50, cache_mapping=True, reverse_order=False)The arguments are:
max_length (required):
This is the maximum number of elements to store.
cache_mapping (optional):
If this is True the mapping between keys and values is stored in a more efficient way. This improves performance at the expense of greater memory usage.
reverse_order (optional):
If this is False the elements with the lowest max_length values are maintained. If this is True the elements with the highest max_length values are maintained.
The LimitedDict class can then be used like a dict:
.. code:: bash
from limited_dict import LimitedDict my_dict = LimitedDict(max_length=3, cache_mapping=False, reverse_order=False) my_dict['a'] = 1 my_dict['b'] = 10 my_dict['c'] = 0 my_dict['d'] = 5 my_dict['e'] = 7 print my_dict [('c', 0), ('a', 1), ('d', 5)]
It only stores max_length elements so some elements previously specified may no longer exist in the structure. Trying to access such elements will raise a KeyError:
.. code:: bash
my_dict['e'] Traceback (most recent call last): File "
", line 1, in File "limited_dict/limited_dict.py", line 48, in getitem raise KeyError(key) KeyError: 'e' my_dict['c'] 0
You can iterate over keys and values in the same way as a dict:
.. code:: bash
for key, value in my_dict.items(): ... print("{key}:{value}".format(key=key, value=value)) ... ... c:0 a:1 d:5