On 2008-06-18, Robert Bossy <[EMAIL PROTECTED]> wrote: > Hi, > > I wish to know how two dict objects are compared. By browsing the > archives I gathered that the number of items are first compared, but if > the two dict objects have the same number of items, then the comparison > algorithm was not mentioned.
You could consider hashing, if the order of hashing is independent on the end result and it is fast enough. Different hash results are different dicts, equal hashes give you no conclusion. Then, you are probably down to comparing keys (since keys are unique and the number of keys in both dicts are the same, one direction of comparing is enough) and values. Since dict is designed to be fast in accessing keys, the performance should be not entirely disastreus. > domain-specific language where there's a data structure similar to > python dict and I need an source of inspiration for implementing > comparisons. If you have a choice in data structures, you may want to have an ordered dictionary (or sorted dict), where keys are sorted, making it much easier to decide about equality. The price you pay at least is less fast dictionary modifications and possibly also less fast key access although that also depends on the speed of hashing the key. There are also discussions about ordered dictionaries in Python (I believe they are called OrderedDict or SortedDict). There is also a PEP about them. Sincerely, Albert -- http://mail.python.org/mailman/listinfo/python-list
