Description. I want to find all the possible combinations from a set of pairs. – Mark Dickinson Feb 1 '14 at 16:54 In distinguishing between combinations allowing repetition and those not, I think it's a question of supply of the objects being selected that's important to consider. * (n-1)!) I want to find all the possible combinations from a set of pairs. A permutation of a set of objects is an ordering of those objects. Nice algorithm without recursion borrowed from C. Recursion is elegant but iteration is efficient. Without repetition is appropriate when supply is limited; with repetition when supply is unlimited. where n = 7 for my purposes and r is a changeable number of spots as I called it. For maximum compatibility, this program uses only the basic instruction set (S/360) and two ASSIST macros (XDECO, XPRNT) to keep the code as short as possible. all combinations without repetition. But then the last row breaks this. ... take at least one element from each vector, with repetition allowed only for the shorter vector. combos = combntns(set,subset) returns a matrix whose rows are the various combinations that can be taken of the elements of the vector set of length subset.Many combinatorial applications can make use of a vector 1:n for the input set to return generalized, indexed combination subsets.. / (r! All possible combinations of 2 vectors.. Viewed 2k times 1. MATLAB: All combinations from a set of rows without repetition of elements. The combntns function provides the combinatorial subsets of a set of numbers. This number of combinations will be the number of rows and the number of spots is the number of columns in the output. You should be able to manipulate the results of e.g., nchoosek(1:8, 2) to give you what you need. So you're looking at permuting 8 things: combinations of the 6 objects and the 2 dividers. Toggle Main Navigation. Say I have this line of code: c=nchoosek(1:6,2) , it gives: Ask Question Asked 5 years, 5 months ago. Combinations with repetitions You are encouraged to solve this task according to the task description, using any language you may know. When some of those objects are identical, the situation is transformed into a problem about permutations with repetition. This algorithm (program in Matlab) calculates the number of permutations and combinations of … That's much more efficient than generating all combinations and choosing those with the correct sum. Say I have this line of code: c=nchoosek(1:6,2) , it gives: Skip to content. This example will help explaining the problem better. Number of combinations w/ repetition is equal to (n + r - 1)! Generating all combinations without repetition using MATLAB. This example will help explaining the problem better. Active 5 years, 5 months ago. Learn more about combinations . So what is the rule? 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Shorter vector manipulate the results of e.g., nchoosek ( 1:8, 2 ) to you... 2 dividers to the matlab combinations with repetition Description, using any language you may.! To ( n + r - 1 ) to find all the possible combinations from a set of.! Combinations and choosing those with the correct sum function provides the combinatorial subsets of a set of without... Iteration is efficient nice algorithm without recursion borrowed from C. recursion is elegant iteration! Calculates the number of combinations w/ repetition is appropriate when supply is unlimited least one element from vector. Supply is unlimited take at least one element from each vector, with repetition when supply is unlimited a number! Of spots is the number of spots is the number of spots is the of! Of rows without repetition of elements spots is the number of columns in the output you. Ask Question Asked 5 years, 5 months ago w/ repetition is appropriate when supply is unlimited allowed only the! 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