VChooseKR 1.0

VChooseKR(V, K) creates a matrix, which rows are all combinations created by choosing K elements of the vector V without order and with repetitions.INPUT: V: Array of class DOUBLE, SINGLE, (U)INT8/16/32/64, LOGICAL, CHAR. Prefer (U)INT8 or (U)INT16 for speed. K: Number of elements to choose.OUTPUT: Y: Matrix of size [(N+K-1 over K), K] and same class as V.EXAMPLES: Choose 2 elements from [1,2,3,4]: VChooseKR(1:4, 2) ==> [1,1; 1,2; 1,3; 1,4; 2,2; 2,3; 2,4; 3,3; 3,4; 4,4] For speed cast the input to integer types if possible: Y = VChooseKR(int8(1:64), 3) is 6 times faster than with DOUBLEs! To get the combinations of cell arrays, use the combinations of the index: C = {'a', 'b', 'c', 'd'}; C2 = C(VChooseKR(1:4, 2)) ==> C2 = {'a','a'; 'a','b'; 'a','c'; 'a','d'; 'b','b'; 'b','c'; ... 'b','d'; 'c','c'; 'c','d'; 'd','d'}This MEX version is faster than COMBINATOR of Matt Fig: E.g. ~7 times for K=64, N=2, ~140 times for K=2, N=128. The older PICK of Stefan Stoll is slower than COMBINATOR. See screen shot.Tested: Matlab 6.5, 7.7, 7.8, WinXP, Compilers: BCC5.5, LCC2.4/3.8, Open Watcom 1.8Please run the unit-test TestVChooseKR after compiling or to compare the speed with other functions from the FEX, if they are found in the path.See also: VChooseK (no repetitions, no order): http://www.mathworks.com/matlabcentral/fileexchange/26190VChooseKRO (repetitions, order): http://www.mathworks.com/matlabcentral/fileexchange/26242I'd appreciate suggestions for improvements and bug reports sent through email - thanks.

Requirements:	No special requirements
Platforms:	Matlab
Keyword:	K3d64,  Matlab,  N3d128,  Older,  Screen,  Slower,  Stefan,  Stoll,  Tested,  Winxp
Users rating:	0/10