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foreach-combination

foreach-combination

Enumerate all k length subsets in an array.

Example

var kcomb = require("foreach-combination")
 
var array = [1, 2, 3, "a", "b", "c"]
 
kcomb(array, 3, function(x,y,z) {
  console.log(x, y, z)
})

Output:

1 2 3
1 2 'a'
1 2 'b'
1 2 'c'
1 3 'a'
1 3 'b'
1 3 'c'
1 'a' 'b'
1 'a' 'c'
1 'b' 'c'
2 3 'a'
2 3 'b'
2 3 'c'
2 'a' 'b'
2 'a' 'c'
2 'b' 'c'
3 'a' 'b'
3 'a' 'c'
3 'b' 'c'
'a' 'b' 'c'

Install

npm install foreach-combination

If you want to use this in a browser, then you should use browserify.

API

require("foreach-combination")(array, k, visit(x1,x2,...,xk)

Visits all k size combinations in array in lexicographic order.

  • array is an array
  • k is the size of the combination to visit
  • visit(x1,x2,...xk) is a callback that gets called once for each size k-subset of the array. If visit returns a non-undefined value then the iteration is immediately terminated, and the result of visit is returned.

Returns The result of the last call to visit, or undefined if no value was ever returned.

Note If you know k in advance, you can avoid an extra dispatch by calling require("foreach-combination")[k] directly for any k<32

Credits

(c) 2014 Mikola Lysenko. MIT License