powerset

问题 Is it possible to make a racket function to return powerset of a given list ? Constraints- without explicit recursion use abstract list functions code contained in 2 lines (actual requirement) For eg: (powerset '(1 2)) '((1 2) (1) (2) ()) in any order. The other question I found still uses explicit recursion. My workflow: Taking (powerset '(a b c)) as an example, First get a list of whole numbers up to (expt 2 (length list)) ;'(0 1 2 3 4 5 6 7) Convert them into their respective binary form 2

问题 I am trying to implement a powerset function in Scheme in two ways. One way is using tail recursion, and I did it like this: (define (powerset list) (if (null? list) '(()) ;; if list is empty, its powerset is a list containing the empty list (let ((rest (powerset (cdr list)))) ;; define "rest" as the result of the recursion over the rest of list (append (map (lambda (x) (cons (car list) x)) rest) ;; add the first element of list to the every element of rest (which is a sublist of rest) rest))

问题 Let S(w) be a set of words. I want to generate all the possible n-combination of subsets s so that the union of those subsets are always equal to S(w). So you have a set (a, b, c, d, e) and you wan't all the 3-combinations: ((a, b, c), (d), (e)) ((a, b), (c, d), (e)) ((a), (b, c, d), (e)) ((a), (b, c), (d, e)) etc ... For each combination you have 3 set and the union of those set is the original set. No empty set, no missing element. There must be a way to do that using itertools.combination

问题 Say I have the following class: class A { String name; Double value; } and a list of the above class objects which might have: [{f 2.1}, {c 1.1}, {a 0.3}... and so on] [{n 0.5}, {f 1.9}, {x 0.1}, {a 1.9}, {b 1.1}... and so on] ... and so on all I want is to do the followings: 1. Building power subsets from the internal list items(N.B: skip the single subsets). 2. Push the subset in another List as an object of the above class A like this: a. if f,c is a subset of 1st element then f,c would be

问题 Say I have the following class: class A { String name; Double value; } and a list of the above class objects which might have: [{f 2.1}, {c 1.1}, {a 0.3}... and so on] [{n 0.5}, {f 1.9}, {x 0.1}, {a 1.9}, {b 1.1}... and so on] ... and so on all I want is to do the followings: 1. Building power subsets from the internal list items(N.B: skip the single subsets). 2. Push the subset in another List as an object of the above class A like this: a. if f,c is a subset of 1st element then f,c would be

问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 6 years ago . I wish to define a predicate powerset(X, P) which is true when P is the powerset of X. Should work whether or not P is ground. 回答1: Since you use SICStus Prolog you can use the subseq0(+Sequence, ?SubSequence)

问题 Practically, I've got a set of objects with probabilities, and I want to look at each possible group of them, in order of how likely it is that they're all true assuming they're independent -- i.e. in descending order of the product of the elements of the subsets -- or in order of length if the probabilities are the same (so that (1, 0.5) comes after (0.5)). Example: If I have [ 1, 0.5, 0.1 ] I want [ (), (1), (0.5), (1, 0.5), (0.1), (1, 0.1), (0.5, 0.1), (1, 0.5, 0.1) ] In essence, this

问题 Practically, I've got a set of objects with probabilities, and I want to look at each possible group of them, in order of how likely it is that they're all true assuming they're independent -- i.e. in descending order of the product of the elements of the subsets -- or in order of length if the probabilities are the same (so that (1, 0.5) comes after (0.5)). Example: If I have [ 1, 0.5, 0.1 ] I want [ (), (1), (0.5), (1, 0.5), (0.1), (1, 0.1), (0.5, 0.1), (1, 0.5, 0.1) ] In essence, this

问题 Trying to calculate all the subsets (power set) of the 9-letter string 'ABCDEFGHI'. Using standard recursive methods, my machine hits out of memory (1GB) error before completing. I have no more physical memory. How can this be done better? Language is no issue and results sent to the standard output is fine as well - it does not need to be held all in memory before outputting. 回答1: There is a trivial bijective mapping from the power set of X = {A,B,C,D,E,F,G,H,I} to the set of numbers between

问题 This is my current implementation using bits: Function Array_PowerSet(Self) Array_PowerSet = Array() PowerSetUpperBound = -1 For Combination = 1 To 2 ^ (UBound(Self) - LBound(Self)) ' I don't want the null set Subset = Array() SubsetUpperBound = -1 For NthBit = 0 To Int(WorksheetFunction.Log(Combination, 2)) If Combination And 2 ^ NthBit Then SubsetUpperBound = SubsetUpperBound + 1 ReDim Preserve Self(0 To SubsetUpperBound) Subset(SubsetUpperBound) = Self(NthBit) End If Next