combinations

问题 I have a list of unique tuples each containing 2 elements from 1 to 10. A total number of elements in a list is 45. I would like to divide them into 10 groups each of them containing only numbers from 1 to 10. I have tried solve my problem using this answer: python get groups of combinations that each member appear only once python: from itertools import combinations, chain l = ['A','B','C','D','E', 'F', 'G','H','I','J'] c = list(combinations(l,2)) [set(i) for i in list(combinations(c,5)) if

问题 I am trying to generate an array of all combinations of an arbitrary number of arrays. From the generated array, I would like to add an constraint that the sum of the numbers must lie between two bounds (say 'lower' and 'upper') One method of doing this is to use cartersian, sum the elements, and select the ones that fall within the lower and upper bounds. However, the main limitation is that it is possible to run out of memory given a large number of input arrays. Another method is to use

问题 I need to write a recursive function that calculates all the possible combinations of length "n" in a list, in Python, without importing anything like itertools etc. So what I have so far is: if n == 0: return [[]] elif lst == []: return [] else: rest = subsets(lst[1:], n-1) for next in lst: # Loop through something? return lst[0] + rest #Add something? I seem to be lacking an understanding of how the recursive calls work, can someone explain this to me? 回答1: In the absence of the required

问题 I want to make a combination of 1's and 0's in a 2d array like the following: [[ 1, 1, 1, 1, 0, 0, 0, 0 ], [ 1, 1, 1, 0, 1, 0, 0, 0 ], [ 1, 1, 1, 0, 0, 1, 0, 0 ], [ 1, 1, 1, 0, 0, 0, 1, 0 ], [ 1, 1, 1, 0, 0, 0, 0, 1 ], . . . ] That means a combination of four 1's and four 0's. I have looked at the itertools module's permutations() and combinations() , but couldn't find any suitable functions to perform this combination. 回答1: You can also use combinations to generate unique combinations

问题 I'm trying to generate all possible bytes to test for a machine learning algorithm (8-3-8 mural network encoder). is there a way to do this in python without having 8 loops? Could permutations help? I'd prefer an elegant way to do this, but I'll take what I can get at the moment. desired output: [0,0,0,0,0,0,0,0] [0,0,0,0,0,0,0,1] [0,0,0,0,0,0,1,0] [0,0,0,0,0,0,1,1] [0,0,0,0,0,1,0,0] [0,0,0,0,0,1,0,1] . . . [1,1,1,1,1,1,1,1] 回答1: Yes, there is, itertools.product: import itertools itertools

问题 I have a HashMap<GC, List<RR>> with sample data like: key values gc1 - rr1 - rr2 - rr3 gc2 - rr4 - rr5 gc3 - rr6 And I need to create all possible combinations of RR from different GC like: Combination1: rr1, rr4, rr6 Combination2: rr1, rr5, rr6 Combination3: rr2, rr4, rr6 Combination4: rr2, rr5, rr6 Combination5: rr3, rr4, rr6 Combination6: rr3, rr5, rr6 What I've tried so far is, as @Sanket Makani suggests, to turn my HashMap<GC, List<RR>> into a List<List<RR>> , and then iterate through

问题 I have a very weird problem which has some constrains that make it difficult to solve. I have a list of lists and I want to do the combinations of all items in those lists. Each item has a name and a value. Here is an example: Main List: List 01: Item 01: name:name01, value:value01 Item 02: name:name02, value:value02 List 02: Item 01: name:name03, value:value03 List 03: Item 01: name:name04, value:value04 Item 02: name:name05, value:value05 The end result should look like this: Some List:

问题 I have often used itertools module in Python but it feels like cheating if I don't know the logic behind it. Here is the code to find combinations of string when order is not important. def combinations(iterable, r): # combinations('ABCD', 2) --> AB AC AD BC BD CD # combinations(range(4), 3) --> 012 013 023 123 pool = tuple(iterable) n = len(pool) if r > n: return indices = list(range(r)) yield tuple(pool[i] for i in indices) while True: for i in reversed(range(r)): if indices[i] != i + n - r

问题 here is my simplified data set: foo <- data.frame(var1= c(1:10), var2=rep(1:5,2),var3=rep(1:2,5),var4=rep(3:7,2) ) all together 20 variables foo var1 var2 var3 var4 ... var20 1 1 1 1 3 2 2 2 2 4 3 3 3 1 5 4 4 4 2 6 5 5 5 1 7 6 6 1 2 3 7 7 2 1 4 8 8 3 2 5 9 9 4 1 6 10 10 5 2 7 I need to get a unique combination of 3 variables and its sum for each period ie. sth like var1var2var3 var1var3var4 var1var5var18 etc... 1 6 sum 2 6 3 7 4 10 5 11 6 9 7 10 8 13 9 14 10 17 note that var1var3var5 is the

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: How can I create cartesian product of vector of vectors? I'm having some logical issues figuring out how to generate all combinations of elements in a 2d vector. Here, I create a 2D vector. Neither dimension's size can be assumed. #include <iostream> #include <vector> using namespace std; int main() { srand(time(NULL)); vector< vector<int> > array; // This creates the following: // array[0]: {0, 1, 2} // array[1