set

问题 I'm doing some set operations in Python, and I noticed something odd.. >> set([1,2,3]) | set([2,3,4]) set([1, 2, 3, 4]) >> set().union(*[[1,2,3], [2,3,4]]) set([1, 2, 3, 4]) That's good, expected behaviour - but with intersection: >> set([1,2,3]) & set([2,3,4]) set([2, 3]) >> set().intersection(*[[1,2,3], [2,3,4]]) set([]) Am I losing my mind here? Why isn't set.intersection() operating as I'd expect it to? How can I do the intersection of many sets as I did with union (assuming the [[1,2,3],

问题 Given a Set, generate all subsets of length n. Sample input: set = new Set(['a', 'b', 'c']), length = 2 Sample output: Set {'a', 'b'}, Set {'a', 'c'}, Set {'b', 'c'} How to do this efficiently, without converting the Set to an Array ? I already have a good solution for arrays as input: function* subsets(array, length, start = 0) { if (start >= array.length || length < 1) { yield new Set(); } else { while (start <= array.length - length) { let first = array[start]; for (subset of subsets(array

问题 I'm kind of new to Android and I have to make a Bluetooth connection between two PCBs. I saw a line of code in API guides and I still haven't figure out what it means. I wonder if someone can help me. Here's that code: Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices(); What I can't understand is Set<BluetoothDevice> ! Why does they put something between "< >" . I've also seen than in ArrayAdapter<String> . What these elements do? 回答1: That makes the Set a Generic set.

问题 So if we can get past the "should you?" question ... does anyone know how to set the value of an integer in prototype? Number.prototype.add = function(num){ var newVal = this.valueOf() + num; this.valueOf(newVal); return newVal; } var rad = 4001.23; document.write(rad.add(10) + '<br/>' + rad); You'll notice rad.add(10) returns the number contained in the variable "rad" plus 10, but I would really like to change the value of rad from within the prototype add function (something I know this

问题 consider the following script: # multipleSmallFrozensets is a list of 7 frozensets of differenet number of string objects multipleSmallFrozensets = [ frozenset({'YHR007C', 'YHR042W'}), frozenset({'YPL274W'}), frozenset({'YCL064C'}), frozenset({'YBR166C'}), frozenset({'YEL041W', 'YJR049C'}), frozenset({'YGL142C'}), frozenset({'YJL134W', 'YKR053C'})] # singleFrozenset is a frozenset of 3410 string objects singleFrozenset = frozenset({'YIL140W','YLR268W','YLR357W','YJL155C','YHR067W', 'YAL008W',

问题 I've been studying for a coding exam by doing the HackerRank test cases, for the most part I've been doing well, but I get hung up on some easy cases and you all help me when I can't see the solution. I'm working on this problem: https://www.hackerrank.com/challenges/ctci-ransom-note A kidnapper wrote a ransom note but is worried it will be traced back to him. He found a magazine and wants to know if he can cut out whole words from it and use them to create an untraceable replica of his

问题 Colouring problem : Hello, I'm trying to implement a bool function that returns true when a color can be extended to a country and false otherwise but I'm having trouble working with sets as we cannot pattern match them... My code : type Country = string;; type Chart = Set<Country*Country>;; type Colour = Set<Country>;; type Colouring = Set<Colour>;; (* This is how you tell that two countries are neghbours. It requires a chart.*) let areNeighbours ct1 ct2 chart = Set.contains (ct1,ct2) chart

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Python: simple list merging based on intersections I am trying to classify objects. Each object is identified by a unique identifier property called id . So my classification logic goes like this. First i prepare a list of objects and then the classification function takes 2 objects at a time and returns a frozenset containing their id . So if object1 and object5 are in the same category a frozenset(id1,id5) is

问题 When I do something like: U = [(1.0, 0.0), (0.0, 1.0)] set(U) It gives me: {(0.0, 1.0), (1.0, 0.0)} I just want to convert the list into a set. Any help? Thanks 回答1: Sets are not ordered. Dictionaries are not ordered either. If you want to preserve a specific order, then use a list. >>> ''.join(set("abcdefg")) 'acbedgf' >>> ''.join(set("gfedcba")) 'acbedgf' >>> ''.join(set("1234567")) '1325476' >>> ''.join(set("7654321")) '1325476' Obviously, when you iterate over a set some kind of order has

问题 E.g. for List(1, 1, 1, 2, 3, 3, 4) it would be Set(1, 3) , because 1 and 3 are the only elements which occur multiple times. 回答1: val s = List(1, 1, 1, 2, 3, 3, 4) // a list with non-unique elements (s diff s.distinct) toSet // Set(1, 3) 回答2: A bit more convoluted but you can avoid having to call toSet.toList , first group the integers: scala> s.groupBy(identity) res13: scala.collection.immutable.Map[Int,List[Int]] = Map(2 -> List(2), 4 -> List(4), 1 -> List(1, 1, 1), 3 -> List(3, 3)) Then