On 2018-01-27 18:01, qrious wrote:
I need a data structure and a corresponding (hopefully fast) mechanism
associated with it to do the following. While I am looking for the concept
first, my preference for implementation of this will be in Python.
[c1, c2,..., cn] is a list of strings (for my own implementation, but could be
any other type for the generic problem). There will be many hundreds, if not
thousands, of such lists with no shared member.
The method getAssocList(e) will return lists of the lists for which e is an
element.
Here a hash may be a way to go, but need help in figuring it out. Also, can
there be a faster and more memory efficient solution other than hashes?
You could build a dict where the key is the element and the value is a
list of those lists that contain that element.
The 'defaultdict' class is useful for that.
from collections import defaultdict
assoc_dict = defaultdict(list)
for lst in list_of_lists:
for elem in lst:
assoc_dict[elem].append(lst)
# Optionally convert to a plain dict once it's built.
assoc_dict = dict(assoc_dict)
--
https://mail.python.org/mailman/listinfo/python-list
