set

问题 I am trying to get a function (given as a parameter a set) to return a set whose elements are all the subset formed from the main set. Ex: {1;2;3} -> { {1}, {2}, {3}, {1,2}, {1,3}, {2,3}, {1,2,3} } But I don't exactly know how to make a module that lets me work with a set of sets. What type should I define it as? 回答1: A set of all subsets is called a power set. To implement an algorithm you don't really need a special data structure, as you can represent a set with a list. Correspondingly a

问题 I have a bad-projected database which have a ID sets in text columns like "1,2,5,10". I need to get an intersection of two columns which are set by same way. I don't like to do it using PHP or another scripting language, I also not like MySQL custom functions. Is there any way to get an intersection of two sets given by comma-delimeter strings? Actually I don't need to have full intersection, I just need to know is there same numbers in two sets. If yes, I need to have "1", if no same number,

问题 So I'm trying to find all sub-lists of a list and here is what I have now. I'm new to Python and I don't understand why " Q3_ans=set(ans)" raises an error. I've tried to convert a list to set before and it works. def f2(seq): ''' This is the base case of the recursion from function all_sublists ''' assert len(seq)==2 assert isinstance(x,list) a,b=seq return [[a],[b],[a,b]] def all_sublists(x): ''' This function will generate all of the sublists of a list, not including the empty one, using

问题 This question already has answers here : What is the fastest way to compare two sets in Java? (9 answers) Closed 3 years ago . Given two Sets: how to compare them efficiently in Java? (a) keep them as List s, sort them and compare them. ( Comparable ) (b) keep them as Set s and compare the hashCode of the Sets? background: many comparisons need to be done Sets are small (usually < 5 elements per set). 回答1: The proper way to compare two sets is to use the equals method. I would not worry about

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 6 years ago . I noticed a logical inconsistence between Set and SortedSet interfaces in Java. SortedSet recognizes different objects (by equal()

问题 I'd like to create this function, which selects a random element from a Set: randElem :: (RandomGen g) => Set a -> g -> (a, g) Simple listy implementations can be written. For example (code updated, verified working): import Data.Set as Set import System.Random (getStdGen, randomR, RandomGen) randElem :: (RandomGen g) => Set a -> g -> (a, g) randElem s g = (Set.toList s !! n, g') where (n, g') = randomR (0, Set.size s - 1) g -- simple test drive main = do g <- getStdGen print . fst $ randElem

问题 Is there a collection in c# that supports the inheritance like concept that objects can have of appearing to include all the elements from another as well as themselves? For example: HashSet<animal> animals = new HashSet<animal>(); HashSet<dog> dogs = new HashSet<dog>(); animals.also_appears_to_include(dogs); So if I for example added 2 elements to dogs and 1 to animals, then looked at how many elements animals has I would see 3. Alternatively I could put references to the above mentioned 3

问题 Similar questions have already been asked on SO, but they have more specific constraints and their answers don't apply to my question. Generally speaking, what is the most pythonic way to determine if an arbitrary numpy array is a subset of another array? More specifically, I have a roughly 20000x3 array and I need to know the indices of the 1x3 elements that are entirely contained within a set. More generally, is there a more pythonic way of writing the following: master=[12,155,179,234,670

问题 I am trying to create a method that will return all subsets of a set. For example if I have the collection 10,20,30 I will like to get the following output return new List<List<int>>() { new List<int>(){10}, new List<int>(){20}, new List<int>(){30}, new List<int>(){10,20}, new List<int>(){10,30}, new List<int>(){20,30}, //new List<int>(){20,10}, that substet already exists // new List<int>(){30,20}, that subset already exists new List<int>(){10,20,30} }; because the collection can also be a

问题 Suppose I have a set of tuples representing URLS with "scores": {(0.75, 'http://www.foo.com'), (0.33, 'http://www.bar.com'), (0.5, 'http://www.foo.com'), (0.66, 'http://www.bar.com')} . What is a concise way for me to filter out duplicate URLS, returning only the URL with the lowest score? That is, from the example set above, I want to get the following set, where each URL appears only once, with the lowest corresponding score from the original set: {(0.5, 'http://www.foo.com'),(0.33, 'http:/