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up vote 1 down vote favorite

Hey i have a simple question i cant find an answer, i´m trying to generate some raw-data for a chart

lets say i have an array like :

[1,0,0,1,2,0]

is there a way to make an array out of it that has nested arrays that represent the count of duplicate entrys ? 

[[0,3],[1,2],[2,1]]

here is some code that does the trick, but saves the count as objects

var array = [1,0,0,1,2,0];
var length = array.length;
var objectCounter = {};

for (i = 0; i < length; i++) {

    var currentMemboerOfArrayKey = JSON.stringify(array[i]);

    var currentMemboerOfArrayValue = array[i];

    if (objectCounter[currentMemboerOfArrayKey] === undefined){

         objectCounter[currentMemboerOfArrayKey] = 1;
    }else{
        objectCounter[currentMemboerOfArrayKey]++;
    }
}

but objectCounter returns them like 

{0:3,1:2,2:1}

but i need it as an array i specified above ?

for any help, thanks in advance

share|improve this question
1  
You can just convert it to an array with a forin loop. Or initialize with Array() –  Manishearth Dec 16 '13 at 9:30

6 Answers 6

up vote 3 down vote accepted

Try

var array = [1, 0, 0, 1, 2, 0];

function counter(array) {
    var counter = [],
        map = {}, length = array.length;
    $.each(array, function (i, val) {
        var arr = map[val];
        if (!arr) {
            map[val] = arr = [val, 0];
            counter.push(arr);
        }
        arr[1] += 1;
    })

    return counter;
}
console.log(JSON.stringify(counter(array)))

Demo: Fiddle

share|improve this answer
    
Yeah that for me is the perfect solution ! thank you very much and the others too –  john Smith Dec 16 '13 at 9:42
    
Could you explain how this code works? I think it is quite interesting how you link map[val] and arr to the same array and how you've taken advantage of the closure to store the map variable. –  forsvunnet Dec 16 '13 at 9:48
up vote 2 down vote

Functional way of doing this, with Array.reduce and Array.map

var data = [1,0,0,1,2,0];

var result = data.reduce(function(counts, current) {
    counts[current] = current in counts ? counts[current] + 1: 1;
    return counts;
}, {});

result = Object.keys(result).map(function(current){
    return [parseInt(current), result[current]];
});
console.log(result);

Output

[ [ 0, 3 ], [ 1, 2 ], [ 2, 1 ] ]
share|improve this answer
    
Nice elegant, functional solution! How could I adapt it to work on, for example, an array of letters? –  i_made_that May 8 at 17:53
    
@i_made_that What do you want as the output? –  thefourtheye May 9 at 4:26
up vote 1 down vote

Your existing object can be turned into an array with a simple for..in loop. Also your existing code that produces that object can be simplified. Encapsulate both parts in a function and you get something like this:

function countArrayValues(array) {
  var counter = {},
      result = [];

  for (var i = 0, len = array.length; i < len; i++)
    if (array[i] in counter)
      counter[array[i]]++;
    else
      counter[array[i]] = 1;

  for (i in counter)
    result.push([+i, counter[i]]);

  return result;
}

console.log( countArrayValues([1,0,0,1,2,0]) );

Demo: http://jsfiddle.net/hxRz2/

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up vote 1 down vote

First you need to map the array to an associative object

var arr = [1,0,0,1,2,0];
var obj = {};
for (var i = 0; i < arr.length; i++) {
  if (obj[arr[i]] == undefined) {
    obj[arr[i]] = 0;
  }
  obj[arr[i]] += 1;
}

Then you can easily turn that object into a 2d matrix like so:

arr = [];
for (var k in obj) {
  arr.push([k, obj[k]]);
}

alert(JSON.stringify(arr));
share|improve this answer
up vote 1 down vote

Try:

var data = [1,0,0,1,2,0];
var len = data.length;
var ndata = [];
for(var i=0;i<len;i++){
    var count = 0;
    for(var j=i+1;j<len;j++){
        if(data[i] == data[i]){
            count ++;
        }
    }
    var a = [];
    a.push(data[i]);
    a.push(count);
    ndata.push(a);   
}
console.log(ndata)

DEMO here.

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up vote 2 down vote

You can turn your object into an array easily:

var obj = {0:3,1:2,2:1};

var arr = [];
for (var key in obj) {
  // optional check against Object.prototype changes
  if (obj.hasOwnProperty(key)) {
    arr.push([+key, obj[key]]);
  }
}

Note: The object keys are strings, so i converted them back to numbers when placed in the array.

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