How to sort a part of an array with javascript?

Question

I have an array having many objects. I am trying to sort the first half of the array with ascending order. And the second half of the array with ascending order too. The code below is an array example and my way to do it. I am thinking is there a smarter way to sharpen the code and get the same result? Can anyone help? Thanks in advance!

var data = [
    {id:1, x: 33},
    {id:2, x: 22},
    {id:3, x: 11},
    {id:4, x: 3},  
    {id:5, x: 2},
    {id:6, x: 1}  
];
var data1 = [];
for(var i=0; i<3; i++){
  data1.push(data[i]);
}
data1.sort (function(a,b) { return a.x - b.x; });

var data2 = [];
for(var i=3; i<6; i++){
  data2.push(data[i]);
}
data2.sort (function(a,b) { return a.x - b.x; });

data = data1.concat(data2);
console.log(data);

FYI, you can shorten it a bit by getting rid of the for loops, and doing this instead: var data1 = data.splice(data.length/2); var data2 = data — user1106925
– user1106925, Commented Mar 29, 2016 at 20:15

xrgb · Accepted Answer · 2016-03-29 20:28:29Z

3

Using splice would tighten it up:

var data = [
    {id:1, x: 33},
    {id:2, x: 22},
    {id:3, x: 11},
    {id:4, x: 3},  
    {id:5, x: 2},
    {id:6, x: 1}  
];

// splice out and sort the first half of data
var data1 = data.splice(0,data.length / 2);
data1.sort (function(a,b) { return a.x - b.x; });

// sort the second half
data.sort (function(a,b) { return a.x - b.x; });

data = data1.concat(data);
console.log(data);

edited Mar 29, 2016 at 20:28

answered Mar 29, 2016 at 20:18

xrgb

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2 Comments

RomanPerekhrest Over a year ago

why this data.splice(1,data.length / 2) should work in such case ? console.log(data) gives the following order of x attribute: 3, 11, 22, 1, 2, 33

xrgb Over a year ago

@nnnnnn yes, it should. Fixing.

Nina Scholz · Accepted Answer · 2016-03-29 21:24:32Z

2

You can slice the array with Array#slice() and concat with Array#concat().

function sortX(a, b) {
    return a.x - b.x;
}

var data = [{ id: 1, x: 33 }, { id: 2, x: 22 }, { id: 3, x: 11 }, { id: 4, x: 3 }, { id: 5, x: 2 }, { id: 6, x: 1 }],
    first = data.slice(0, data.length / 2 | 0).sort(sortX),
    second = data.slice(data.length / 2 | 0, data.length).sort(sortX);

data = first.concat(second);
document.write('<pre>' + JSON.stringify(data, 0, 4) + '</pre>');

edited Mar 29, 2016 at 21:24

answered Mar 29, 2016 at 20:18

Nina Scholz

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Comments

CORSAIR · Accepted Answer · 2016-03-29 20:29:55Z

1

/**
 * This method allows you to split array in two peaces
 * @param Array array - the array which you want to split
 * @returns array
 */
function sort2Array(array) {
    var results = [],
        length = Math.ceil(array.length / 2),
        iterations = array.length / length;
    for (var i = 0; i < iterations; i++) {
        var peace = array.slice(i * length, (i + 1) * length);
        results.push(peace.sort(function(a, b) { return a.x - b.x; }));
    }

    return results[0].concat(results[1]);
}

var data = [
    { id: 1, x: 33 },
    { id: 2, x: 22 },
    { id: 3, x: 11 },
    { id: 4, x: 3 },
    { id: 5, x: 2 },
    { id: 6, x: 1 }
]

sort2Array(data);

answered Mar 29, 2016 at 20:29

CORSAIR

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Comments

user1759333 · Accepted Answer · 2016-03-29 20:47:23Z

0

var data = [
    {id:1, x: 33},
    {id:2, x: 22},
    {id:3, x: 11},
    {id:4, x: 3},  
    {id:5, x: 2},
    {id:6, x: 1}  
];
var sort_fn = function(a,b) { return a.x - b.x; };
function half_sort(p) {
    var m = p.length/2;
    return Array.prototype.concat(
      p.slice(0, m).sort(sort_fn),
      p.slice(m).sort(sort_fn) )
}
var result = half_sort(data)

edited Mar 29, 2016 at 20:47

answered Mar 29, 2016 at 20:26

user1759333

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Comments

vorillaz · Accepted Answer · 2016-03-29 20:53:58Z

0

Using ES6

let data = [
    {id:1, x: 33},
    {id:2, x: 22},
    {id:3, x: 11},
    {id:4, x: 3},  
    {id:5, x: 2},
    {id:6, x: 1}  
];
const up = data.slice(0,data.length/2).sort((prev,next) => prev.x - next.x);
const low = data.slice(data.length/2,data.length).sort((prev,next) =>  next.x - prev.x);
data = up.concat(low)

answered Mar 29, 2016 at 20:53

vorillaz

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