set

问题 AFAIK, F# Map and set are implemented as red-black trees, so I guess that an iteration on these would be in-order traversal. I did some test and the iteration results are always sorted. But I want to make it sure. Is it in-order traversal? 回答1: The documentation on MSDN is pretty good for figuring this out. For instance, the return value for Set.toSeq is "An ordered sequence of the elements of set." It looks like the answer to your question is yes, for both maps and sets. 回答2: AFAIK, F# Map

问题 I m seeking some equivalent in C of python's set() variable type any ideas? here is the python doc about sets http://docs.python.org/2/library/sets.html and could you explain/link me a help for this? please 回答1: No, there isn't. The Python datatype relies on a lot of things regarding Python objects that the more low-level data you typically work with in C simply don't have. Like being able to compare two "objects" reliably, regardless of their type or internal structure. The more you know

问题 I have a Dataframe that contains sets of ids in one column and dates in another: import pandas as pd df = pd.DataFrame([['2018-01-01', {1, 2, 3}], ['2018-01-02', {3}], ['2018-01-03', {3, 4, 5}], ['2018-01-04', {5, 6}]], columns=['timestamp', 'ids']) df['timestamp'] = pd.to_datetime(df['timestamp']) df.set_index('timestamp', inplace=True) ids timestamp 2018-01-01 {1, 2, 3} 2018-01-02 {3} 2018-01-03 {3, 4, 5} 2018-01-04 {5, 6} What I am looking for is a function that can give me the ids for the

问题 I am unable to figure out why this code doesn't work >>> my_list = [1,2,3,4,5] >>> my_set = {*my_list} File "<stdin>", line 1 my_set = {*my_list} ^ SyntaxError: invalid syntax *args is used in python to unpack list. My expectation was that the above operation would create a set but it didn't. Can *args and **kwargs in Python be only used to pass arguments as function ? I am aware of the set() function but curious why this syntax doesn't work. 回答1: Thanks to PEP0448, these days it does work,

问题 I'm looking for built-in alternatives of HashSet and Dictionary objects that have better performance than lists but do not use the internal GetHashCode method. I need this because for the class I have written, there is no way of writing a GetHashCode method that fulfills the usual contract with Equals other than public override int GetHashCode() { return 0; } // or return any other constant value which would turn HashSet and Dictionary into ordinary lists (performance-wise). So what I need is

问题 For me, an integer set seems to be a foldable data structure. Why is Data.IntSet not an instance of Foldable ? My actual intention is to use find on an IntSet . How can I implement find for Data.IntSet ? 回答1: IntSet can't be Foldable from base package because it doesn't have kind * -> * . ghci> :t foldr foldr :: Foldable t => (a -> b -> b) -> b -> t a -> b ghci> :k Foldable Foldable :: (* -> *) -> Constraint ghci> import Data.IntSet (IntSet) ghci> :k IntSet IntSet :: * In simple words, to be

问题 I am reading some line segments from cin. Each line segment is represented by a start and end point. 2D. X and Y. The input is not sorted. It is in random order. (Update:But I need them sorted first by X and then by Y) I can read in all the segments, store them in a vector and then call std::sort. On the other hand, I can create an empty std::set and insert each segment as it arrives. The set will automatically maintain sorted order. Which of the two approaches is more efficient? Update: The

问题 I want to create an class that represents an integer set using a HashSet<int> . I want it to keep track of which values are included in the set using that internal container. I've done this so far: class SetInteger { HashSet<int> intTest= new HashSet<int>(); intTest.Add(1); intTest.Add(2); intTest.Add(3); intTest.Add(4); intTest.Add(5); intTest.Add(6); intTest.Add(7); intTest.Add(8); intTest.Add(9); intTest.Add(10); } So, here I think I'm adding some values to the HashSet , but I dont see how

问题 I'm working on a something related to roughset right now. The project uses alot of sets operation and manipulation. I've been using string operations as a stop gap measure for set operation. It has worked fine until we need to process some ungodly amount of data ( 500,000 records with about 40+ columns each ) through the algorithm. I know that there is no set data structure in .net 2.0(2.0 was the latest when I started the project) I want to know if there is any library that offer fast set

问题 I made a little playground to do some tests on Set operations with custom objects but they are still failing and I have no idea why. class User: NSObject { let id: String init(id: String) { self.id = id super.init() } override var hashValue: Int { get { return id.hashValue } } override var description: String { get { return id } } } func ==(lhs: User, rhs: User) -> Bool { return lhs.hashValue == rhs.hashValue } Then, I made two sets of User objects: let user1 = User(id: "zach") let user2 =