Version

1.1.0

Fixed bugs

23.09.2024 - Edge cases are handled and the codespace is simplified. 25.09.2023 - unChoices did not reflect always, fixed now.

Custom Permutation Generator

1.1. require

const CustomPermutation = require('custom-permutation')

1.2. import

import CustomPermutation from "custom-permutation";

2. Constructor

CustomPermutation(elList:[els...], choices:{ index: [els...]] }, nonChoices:{ index: [els...]] })

3. Usage explanation

example:

CustomPermutation(["a", "b", "c"], {"1": ["a", "b"]}, {"0": ["a"]})

Permutate 3 elements which are "a", "b" and "c" with below rules

- choices rule:

{ "1": ["a", "b"] }

At index=1 there can only be the element "a" or "b"

- nonChoices rule:

{ "0": ["a"] }

At index=0 there can NOT be the element "a"

Note: given index are considered as 0 based: [index=0, index=1, etc.]

4. Result set explanation:

Let's see all permutations, and which ones are valid or not.

• ["a", "b", "c"] // violates nonChoices rule: _first element is "a", but shouldn't be "a"
• ["a", "c", "b"] // violates nonChoices rule: first element is "a", but shouldn't be "a"
• ["b", "a", "c"]
• ["b", "c", "a"] // violates choices rule: second element is "c" but "a" or "b" is desired
• ["c", "a", "b"]
• ["c", "b", "a"]

So there are just 3 results that should be generated with this parameters.

5. Complete example

1. Create permutation

let customPerm = new CustomPermutation(
    ["a", "b", "c"],
    { "1": ["a", "b"] },
    { "0": ["a"] }
);

2. Get next value

2.1. Use with next

let next = customPerm.next();

while (next) {
    console.log(next)
    next = customPerm.next();
}

2.2. Or use with generator

let generator = customPerm.generator();
let next = generator.next();

while (!next.done) {
    console.log(next.value)
    next = generator.next();
}

3. Output

["b", "a", "c"]
["c", "a", "b"]
["c", "b", "a"]