¿Cómo obtener todas las combinaciones posibles de múltiples listas con diferentes índices solo en javascript? [duplicar]
Supongamos que tengo las siguientes listas:
const list1 = [1,2,3,4,5]
const list2 = [6,7,8,9,10]
const list3 = [11,12,13,14,15]
const list4 = [16,17,18,19,20]
¿Cómo obtengo todas las combinaciones posibles pero solo con índices diferentes?
Entonces, por ejemplo, el resultado [1,6,11,16]no funcionaría.
Necesitaría todas las combinaciones como:
[1, 2, 3, 4, 5],
[1, 2, 3, 4, 10],
[1, 2, 3, 9, 5].
[1, 2, 3, 9, 10],
[1, 2, 8, 4, 5],
[1, 2, 8, 9, 5],
[1, 2, 8, 4, 10],
[1, 2, 8, 9, 10],
...
[6, 2, 3, 4, 5],
[6, 2, 13, 14, 20]
etcétera...
Por lo tanto, el índice de cada lista solo debe usarse una vez. No puede utilizar el valor de lista1[0] y de otro índice de lista[0].
También necesitaría saber de dónde proviene cada elemento de las listas devueltas.
Aceptado
Esto parece resolver lo que quieres.
// Using a generator because this can yield a lot of values. Making an array
// from a generator is easy, and generator results can be fetched one after the other,
// reducing memory load.
function* generateIndexCombinations(...lists) {
// Fetch how many cell we needs in our results.
const size = Math.max(...lists.map(l => l.length));
// Using a helper so we can add the index parameter. We could also do by
// slicing the lists, but this would have much larger memory footprint.
function* doGenerate(lists, index, acc) {
// Recursion end case.
if (index >= size) {
yield acc;
return;
}
for (const list of lists) {
if (list.length > index) {
// For each remaining list, create a copy of acc including the index value.
const newAcc = [...acc, list[index]];
// Generate the combinations of the tail to be added in acc and re-yield them.
yield* doGenerate(lists, index + 1, newAcc)
}
}
}
yield* doGenerate(lists, 0, []);
}
const list1 = [1, 2, 3, 4, 5];
const list2 = [6, 7, 8, 9, 10];
const list3 = [11, 12, 13, 14, 15];
const list4 = [16, 17, 18, 19, 20];
const table = document.querySelector('table');
// Option 1: get each combination one after the other.
for(let c of generateIndexCombinations(list1, list2, list3, list4)) {
const tr = document.createElement('tr');
for (let v of c) {
const td = document.createElement('td');
td.textContent = v;
tr.appendChild(td);
}
table.appendChild(tr);
}
// Option 2: Store all combinations in an array.
console.log([...generateIndexCombinations(list1, list2, list3, list4)]);table td {
padding: 0 0.25em;
}<table>
</table>Expandir fragmento
Editar : si también necesita asociar cada valor con la lista de la que proviene, usaría una función de mapeo de la siguiente manera:
// Using a generator because this can yield a lot of values. Making an array
// from a generator is easy, and generator results can be fetched one after the other,
// reducing memory load.
function* generateIndexCombinations(lists, mapper = x => x) {
// Fetch how many cell we needs in our results.
const size = Math.max(...lists.map(l => l.length));
// Using a helper so we can add the index parameter. We could also do by
// slicing the lists, but this would have much larger memory footprint.
function* doGenerate(lists, valueIndex, acc) {
// Recursion end case.
if (valueIndex >= size) {
yield acc;
return;
}
for (let listIndex = 0; listIndex < lists.length; listIndex++) {
const list = lists[listIndex];
if (list.length > valueIndex) {
const val = mapper(list[valueIndex], listIndex, valueIndex, lists);
// For each remaining list, create a copy of acc including the index value.
const newAcc = [...acc, val];
// Generate the combinations of the tail to be added in acc and re-yield them.
yield* doGenerate(lists, valueIndex + 1, newAcc)
}
}
}
yield* doGenerate(lists, 0, []);
}
const list1 = [1, 2, 3, 4, 5];
const list2 = [6, 7, 8, 9, 10];
const list3 = [11, 12, 13, 14, 15];
const list4 = [16, 17, 18, 19, 20];
const table = document.querySelector('table');
// Example 1: without mapper, get each combination one after the other.
for (let c of generateIndexCombinations([list1, list2, list3, list4])) {
const tr = document.createElement('tr');
for (let v of c) {
const td = document.createElement('td');
td.textContent = v;
tr.appendChild(td);
}
table.appendChild(tr);
}
// Example 2: Store all combinations in an array, using the new optional mapper to map
// each value to another.
function listCombinationValueMapper(value, listIndex, valueIndex, lists) {
return {
value,
listIndex,
valueIndex,
// The source list.
source: lists[listIndex]
};
}
const combinations = [...generateIndexCombinations(
[list1, list2, list3, list4],
listCombinationValueMapper
)];
console.log(JSON.stringify(combinations));table td {
padding: 0 0.25em;
}<table>
</table>Expandir fragmento
