Separate an array into groups?

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Separate an array into groups?

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#2 by (2 votes)
#3 by (2 votes)
#4 by (0 votes)

6

I have the following code answered by a question similar to this but I would like to upgrade, this is the current function:

function separar(base, maximo) {
  var resultado = [[]];
  var grupo = 0;

  for (var indice = 0; indice < base.length; indice++) {
    if (resultado[grupo] === undefined) {
      resultado[grupo] = [];
    }

    resultado[grupo].push(base[indice]);

    if ((indice + 1) % maximo === 0) {
      grupo = grupo + 1;
    }
  }

  return resultado;
}

This function will separate a common array into a multidimensional group, according to the number of keys per group that is specified in maximo , but now I need a function similar to the same but with the following change:

The last key of the previous group must be the first of the next group to be generated.

For example:

var meuArray = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
/*separo meu array em grupos de 3 chaves*/
console.log(separar(meuArray, 3));

The above example should print:

   [
      0: [1, 2, 3]
      1: [4, 5, 6]
      2: [7, 8, 9]
      3: [10]
   ]

With the change I would like you to print the array as follows:

   [
      0: [1, 2, 3]
      1: [3, 4, 5]
      2: [5, 6, 7]
      3: [7, 8, 9]
      4: [9, 10, 1]
   ]

In the last group I already include the first key of the next group, how can I do this?

javascript jquery array

asked by anonymous 19.05.2017 / 14:58

4 answers

2

You can check if each group has the right size and within that if make the whole logic to change groups and start the new one already with the first element.

One suggestion might look like this:

function separar(base, maximo) {
  var resultado = [[]];
  var grupo = 0;

  for (var indice = 0; indice < base.length; indice++) {
    resultado[grupo].push(base[indice]);

    if (resultado[grupo].length === maximo) {
      grupo++;
      if (indice + 1 < base.length) resultado[grupo] = [base[indice]];
    }
  }

  return resultado;
}
var meuArray = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

console.log(separar(meuArray, 3));

19.05.2017 / 15:50

2

With few modifications, you can reach the expected result:

function separar(base, maximo) {
  var resultado = [[]];
  var grupo = 0;
  var ultimo_valor = 0;

  for (var indice = 0; indice < base.length; indice++) {

    if (resultado[grupo] === undefined) {
      resultado[grupo] = [];
      // ultimo valor passa a ser o primero da nova linha
      resultado[grupo].push(ultimo_valor);
    }

    resultado[grupo].push(base[indice]);

    ultimo_valor = base[indice];

    if ((resultado[grupo].length) % maximo === 0) {
      grupo = grupo + 1;
    }

  }

  // adiciona ultimo elemento que vai apontar para o primeiro novamente
  if (typeof resultado[grupo] == 'undefined') {
      resultado[grupo] = [ultimo_valor, base[0]];
  } else if (resultado[grupo].length < maximo) {
      resultado[grupo].push(base[0]);
  } else {
      if (typeof resultado[grupo + 1] == 'undefined') {
         resultado[grupo + 1] = [ultimo_valor, base[0]];
      } else {
         resultado[grupo + 1].push(base[0]);  
      }
  }
  return resultado;

}

19.05.2017 / 15:33

0

function separar(arr, len){
    var r = [], i = 0, last;
    r[i] = []; 
    do{
        do{
            r[i].push(last = arr.shift() || r[0][0]);
        }while(r[i].length < len);
        if(arr.length >0){
            r[i++] = [];
            r[i].push(last);
        }
    }while(arr.length != 0);

    return r;
}


var arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
console.log(separar(arr, 3));

arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
console.log(separar(arr, 3));

19.05.2017 / 15:34

Create objects without reference C # Sort phone numbers in a string

score 7 · Accepted Answer

You can optimize the function a bit using Array # slice .

Result:

function separar(base, max) {
  var res = [];
  
  for (var i = 0; i < base.length; i = i+(max-1)) {
    res.push(base.slice(i,(i+max)));
  }
  res[res.length-1].push(base[0]);
  return res;
}

var meuArray = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
/*separo meu array em grupos de 3 chaves*/
console.log(separar(meuArray, 3));

.as-console-wrapper {top: 0; max-height: 100%!important}

The idea is to "cut" the array by the parts, but if the group is not the first cut from the previous index with respect to the current position and finally add the first index of the source array to the last one of the result array .