Sl update giftlist1/23/2024 Projects have deprecated themselves and now recommend SortedĬontainers instead. The performance comparison page documents severalĪlternative implementations of the sorted types described. Indexes like 0 and -1, is optimized and will not require the positional Overhead but avoid positional indexing if able. Indexing a sorted list requires building and maintaining a positional index List is O(log(n)) while it is O(1) for Python’s built-in list data type. The runtime complexity for indexing a sorted One final caveat: indexing a sorted list is fast but not as fast as indexing The hashing protocol also requires that equal keys have equal hashes. Similar limitations also apply to Python’s dict data type which can beĬorrupted by modifying the hash of a key while the item is stored in theĭict. To modify the sorted order position, remove the value, update it, and then add the value back again. The Record instance bob2 can no longer be found in the SortedListīecause modifying the rank changed its sort order position without updating Returns a different comparison key for a given value while the value is stored The compared values must have aĪnother invalid use case of SortedKeyList occurs when the key-function If the data type does not define equality then it inherits equality from Sure the comparison methods or key-function define a total ordering and If the data type defines its own equality, that is _eq_, then make These examples can be summarized in two pieces of advice: The comparison key does not change while the value is stored in the sortedĮqual Record instances have equal rank attributes based on instance The comparison key, rank, is an integer, which has a total ordering. The above example displays that all three requirements are followed: > alice1 = Record ( 'alice', 1 ) > bob2 = Record ( 'bob', 2 ) > carol3 = Record ( 'carol', 3 ) > bob4 = Record ( 'bob', 4 ) > bob2 != bob4 # > sl = SortedList () > bob2 in sl True > bob4 in sl True In terms of instance identity, the situation is simplified. When using equality inherited from object, that is, defined The Record example above is complicated by equality defined as those objects But the key-function will take more memory and be slowerĪs it uses a SortedKeyList which stores a reference to the key for Record._lt_ method and instead use a key-function which called Lexicographical ordering semantics of tuples to define equality and comparison The example above uses a comparison-key method named _cmp_key and the The best way to fix the Record type is to define equality and comparison in Mapping types (not comparable, changed in Python 3). Sets and frozensets (not a total ordering). There are also some built-in Python types and values which lack a total Sequences like list and tuple of values with a total ordering. Of the built-in types inĪll floating-point numbers except float('nan'). Each of these common types defines a total ordering and can be usedįor comparisons in Sorted Containers. Intuitively, a total ordering is best understood through integer and string In pseudocode the three requirements for a total ordering The Record type therefore does not have a In the above example, bob2 and bob4 are equal to each other while bob2 isĪlso strictly less than bob4. bob2 = Record ( 'bob', 2 ) > bob4 = Record ( 'bob', 4 ) > bob2 = bob4 True > bob2 < bob4 # <- Here's the problem.
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