combinations

问题 This question already has answers here : System.OutOfMemoryException when generating permutations (4 answers) Closed 3 years ago . I want to do something with every combination of ternaries for N variables: example with 1: T F U example with 2: TT FT UT TF FF UF UU Is there a way to compute this but only as needed: For example: var combinator = new Combinator<string>(2, {"T","F","U"}); List<String> tt = combinator.Next(); //tt contains {"T","T"} 回答1: You can implement it in an iterator method

问题 How can we create all the combinations of any length for the values in one column and return the distinct count of another column for that combination? Table: +------+--------+ | Type | Name | +------+--------+ | A | Tom | | A | Ben | | B | Ben | | B | Justin | | C | Ben | +------+--------+ Output Table: +-------------+-------+ | Combination | Count | +-------------+-------+ | A | 2 | | B | 2 | | C | 1 | | AB | 3 | | BC | 2 | | AC | 2 | | ABC | 3 | +-------------+-------+ When the combination

问题 I will try to better explain my needs. I need to generate from scrach, a multidirectional array who contain many array. The inner array must be array containing 7 boolean value. I need to have all the combinaisons possible of 7 boolean values. With 7 cases, it make 128 inner arrays. Here an example of output I need, for making it easy to understand : $sequence = array( array(true, true, true, true, true, true, true), array(true, true, true, true, true, true, false), array(true, true, true,

问题 I have a .csv file that contain 5 columns, a_id, b_id, var, lo, up. I would like to create different combinations / patterns between two variables based on a_id, b_id, and var. In addition, at first I would like to delete the records that have no duplicate based on a_id, b_id, because if there is no duplicate, so combination or matching would not be created. As a result, in the dataFile.csv, first record is deleted, because it has no duplicate. For the combination / pattern between two

问题 for an assignment I have to generate a truth table like this: combinations :: Int -> [[Bool]] combinations 3 should output: [[False, False, False],[False, False, True],[False, True, False],[False, True, True][True, False, False][True, False, True],[True, True, False],[True, True, True]] I can do a list comprehension: combinations n = [[a,b] | a<-[True, False], b <-[True, False]] but that doesn't scale for arbitrary numbers. Could you please give me a hint? 回答1: Adding to @chi 's answer, here

问题 I'm not aware nor could I find an algorithm to generate combinations of k items (i.e. k-subsets) lexicographically. I do know algorithms to generate combinations of n choose k, but they don't generate the k-subsets lexicographically. Can somebody help me out with this or point me in the right direction? 回答1: The following algorithm will generate all combinations of elements of a set: procedure all_combinations(S) if length(S) == 0 return {} else all_comb = {} x = first element of S Sx = S-{x}

问题 I'm making a program that calculates a combination given two numbers, ex: java Combination 5 3 would give an answer of 10. I have a method that looks like this: public static int choose(int n, int k) { // chooses k elements out of n total if (n == 0 && k > 0) return 0; else if (k == 0 && n >= 0) return 1; else return choose(n - 1, k - 1) + choose(n - 1, k); How would I be able to use memoization for this in order to make it calculate faster with larger numbers? 回答1: You might be better off

问题 Here we go: I need to query php files which both have a TODO statement as well as my name . Both strings could be anywhere in the document (ie. line) and be positioned anywhere on 0-infinite lines (position 0-n). How to grep query for my name: find -name '*.php' -exec grep -in "fincken" {} + output: ./some/file.php:51: ramon fincken ./somefile.php:2: rfincken How to grep query for the TODOs find -name '*.php' -exec grep -n "TODO" {} + output: ./some/file.php:53: // TODO: foobar! ./some

问题 i'm trying to find all combinations possible using apache pig, i was able to generate permutation but i want to eliminate the replication of values i write this code : A = LOAD 'data' AS f1:chararray; DUMP A; ('A') ('B') ('C') B = FOREACH A GENERATE $0 AS v1; C = FOREACH A GENERATE $0 AS v2; D = CROSS B, C; And the result i obtained is like : DUMP D; ('A', 'A') ('A', 'B') ('A', 'C') ('B', 'A') ('B', 'B') ('B', 'C') ('C', 'A') ('C', 'B') ('C', 'C') but what i'm trying to obtain the result is

问题 I need to generate every combination of 6 numbers from a set of 55. I believe there are 28,989,675 indexes in that set of combinations. I guess I'm running out of memory, because I can generate combinations with 4 numbers but nothing larger than that. How can I fix this problem? I'm using a modification of some code I borrowed from a tutorial here: https://www.youtube.com/watch?v=VyXDQxuIwPU import itertools text_file = open("comb3.txt", "w") harmonics = [28, 33, 36, 38, 40, 43, 45, 47, 48,