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Accepted
Antonio Ruiz
Asked: 2020-06-21 03:06:22 +0800 CST 2020-06-21 03:06:22 +0800 CST

Create multidimensional array in JS with push

  • 772

From this foreach I get different lines (I have commented how I tried, but nothing):

respuesta2.forEach( function(valor2){                              
  //resultados_f2[valor2.ronda].push([parseInt(valor2.victorias_1), parseInt(valor2.victorias_2)]);
  console.log("-"+valor2.ronda+"-> "+parseInt(valor2.victorias_1)+" "+parseInt(valor2.victorias_2));
                              
});

The result of the previous console is the following:

-2-> 1 0
-1-> 1 2
-1-> 2 1

The array I want to get is the following:

var resultados_f2 = [ 
    [[2,1], [1,2]],
    [[1,2]] 
];

How could I do it? I want all the lines that have the same valor2.rondato be in an array within the array resultados_f2.

javascript

1 Answers

  1. Best Answer

    You can do it with the method reduce.
    reducewill iterate over the array generating a new value based on the current element of the iteration and an accumulated value.

    In your case, the accumulated value is an array (what you want as the result).

    const digest = arr =>
    // acc es el valor acumulado
    // cur es el objeto actual
    arr.reduce((acc, cur) => {
        // Sacamos la ronda del current
        const { ronda } = cur;
        // Generamos el elemento a insertar
        const val = [cur.victorias_1, cur.victorias_2];

        // Comprobamos que exista
        // para añadir o crear.
        acc[ronda] = acc[ronda]
                        ? [...acc[ronda], val]
                        : [val];
        return acc;
    }, []); // El segundo argumento de la llamada es un array vacío
            // que será la primera declaración del resultado de reduce.
            // Conviene leer la documentación si no entiendes esto.

    With the following set of values, the result would be as follows.

    const respuesta2 = [
    { ronda: 0, victorias_1: 3, victorias_2: 2},
    { ronda: 1, victorias_1: 6, victorias_2: 5},
    { ronda: 5, victorias_1: 7, victorias_2: 0},
    { ronda: 3, victorias_1: 5, victorias_2: 7},
    { ronda: 1, victorias_1: 4, victorias_2: 1},
    { ronda: 5, victorias_1: 0, victorias_2: 2}
];
const resultados_f2 = digest(respuesta2);
console.log(resultados_f2);
// [
//     [ [ 3, 2 ] ],
//     [ [ 6, 5 ], [ 4, 1 ] ],
//     <1 empty item>,
//     [ [ 5, 7 ] ],
//     <1 empty item>,
//     [ [ 7, 0 ], [ 0, 2 ] ]
// ]

    If you look closely, there are positions in the array that have no value because there was no one with the property rondawith the value of that position.

    Personally, since this can happen, I would choose to output an object , it would be cleaner, but it's up to you.

    const digestToObject = arr =>
    arr.reduce((acc, cur) => {
        // La implementación es idéntica
        // A tratar con un array
    }, {}); // El valor inicial será un object.

    With the same data set as before, this is the result,

    const resultados_f2 = digestToObject(respuesta2);
console.log(resultados_f2);
// {
//     '0': [ [ 3, 2 ] ],
//     '1': [ [ 6, 5 ], [ 4, 1 ] ],
//     '3': [ [ 5, 7 ] ],
//     '5': [ [ 7, 0 ], [ 0, 2 ] ]
// }

    I hope it works.

    • 3