kdb - How to implement combinations of a list -


all

i need combinations , permutations of list.

a function have been implemented permutations.

perm:{[n;l]$[n=1;l;raze .z.s[n-1;l]{x,/:y except x}\:l]}

however, have no idea combinations, this:

l: 1 2 3 comb[2;l] 1 2 1 3 2 3  l: 1 2 3 4 comb[3;l] 1 2 3 1 2 4 1 3 4 2 3 4

thanks!

from solution, can do:

q)comb:{[n;l]$[n=1;l;raze .z.s[n-1;l]{x,/:y y>max x}\:l]} q)comb[2;1 2 3] 1 2 1 3 2 3

another approach using over:

q)perm:{{raze x{x,/:y except x}\:y}[;y]/[x-1;y]} q)comb:{{raze x{x,/:y y>max x}\:y}[;y]/[x-1;y]}

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