javascript array duplicate in another array

Question

Suppose i have this array in javascript

ar = ['C241C12A-45FD-40FF-B26E-B879107E584D||20',
      'AB1BB99D-4396-415A-A5D8-1BEF3E0149CE||33',
      'ADE54113-53D1-4F26-A01C-48EBE37E3CE8||85',
      'DB500FD1-5988-4202-A4AA-727AC29AC67A||85',
      '8A8EAB5A-E0D2-4AA8-96A0-42686FF5EB0C||10',
      '50C29E8A-16C7-4FC2-A186-C3D65F23C627||200',
      '70C79BBB-14C7-4F34-346B-CSSSDFVFZZZ7||200'
    ];

is there any way to get arrays like this

newarray1 = [
      'ADE54113-53D1-4F26-A01C-48EBE37E3CE8||85',
      'DB500FD1-5988-4202-A4AA-727AC29AC67A||85'
      ];
 newarray2 = [
      '50C29E8A-16C7-4FC2-A186-C3D65F23C627||200',
      '70C79BBB-14C7-4F34-346B-CSSSDFVFZZZ7||200'
      ];

Duplicate values that comes after the pipe symbol,grab that value and form a new array based on that

Looping through the entries and creating your new arrays is one way to go. Not sure if there can be a more efficient way of doing this. — Ravi Y, Jan 17 '13 at 05:43
Your example does not seem to be sorted, `10` coming between `85` and `200`? — Bergi, Jan 17 '13 at 05:44

Bergi · Accepted Answer · 2013-01-17T05:53:12.203

var arraysByKey = {};
for (var i=0; i<ar.length; i++) {
    var key = ar[i].split("||")[1];
    if (key in arraysByKey)
        arraysByKey[key].push( ar[i] );
    else
        arraysByKey[key] = [ ar[i] ];
}

The result (arraysByKey) will look like this then:

{
    "10": [
        "8A8EAB5A-E0D2-4AA8-96A0-42686FF5EB0C||10"
    ],
    "20": [
        "C241C12A-45FD-40FF-B26E-B879107E584D||20"
    ],
    "33": [
        "AB1BB99D-4396-415A-A5D8-1BEF3E0149CE||33"
    ],
    "85": [
        "ADE54113-53D1-4F26-A01C-48EBE37E3CE8||85",
        "DB500FD1-5988-4202-A4AA-727AC29AC67A||85"
    ],
    "200": [
        "50C29E8A-16C7-4FC2-A186-C3D65F23C627||200",
        "70C79BBB-14C7-4F34-346B-CSSSDFVFZZZ7||200"
    ]
}

If you only want arrays where "duplicate values" exists, just filter the result:

for (var key in arraysByKey)
    if (arraysByKey[key].length < 2)
        delete arraysByKey[key];

@Bergi one doubt how to check if duplicate exists i means ` if(arraysByKey.length > 0) {` but it gives me undefined error ..although it has some — coolguy, Jan 17 '13 at 05:57
@Bergi ..i think this will do http://api.jquery.com/jQuery.isEmptyObject/ Thanks for the time..will mark it as answer — coolguy, Jan 17 '13 at 06:00

gurvinder372 · Answer 2 · 2013-01-17T05:48:36.877

var keyArray = {};

for ( var counter = 0; counter < ar.length; counter++)
{
  var arValue = ar[ counter ];
  var intVal = ar.split("||")[1];

  if ( keyArray[ intVal ] == null || keyArray[ intVal ] == undefined )
  {
    keyArray[ intVal ] = new Array();
  }
  keyArray[ intVal ].push( arValue  );
}
filterDuplicates();

function filterDuplicates( keyArray )
{
  for ( key in keyArray )
  {

  keyArray[key] = keyArray[key].filter(function(elem, pos, self) {
    return self.indexOf(elem) == pos;
  }
  }
return keyArray();

)

}

Now you have got an array in each index value of 'keyArray' object

score 1 · Answer 3 · answered Jan 17 '13 at 05:44

This is not the most elegant solution, but it will give you an object of your desired arrays.

dupecheck = {};
dupes = {};
$.each(ar, function () {
   var num = this.split('||')[1];

   if (typeof dupecheck[num] !== 'undefined') {
      if (typeof dupes[num] === 'undefined') {
         dupes[num] = [];
         dupes[num].push(dupecheck[num]);
      }
      dupes[num].push(this);
   }

   dupecheck[num] = this;
});

http://jsfiddle.net/38wme/

javascript array duplicate in another array

3 Answers3