How to filter out Duplicates of an array of objects

Question

I have an array of objects which look like this:

$scope.SACCodes = [
    {'code':'023', 'description':'Spread FTGs', 'group':'footings'},
    {'code':'024', 'description':'Mat FTGs', 'group':'footings'},
    {'code':'025', 'description':'CONT. FTGs', 'group':'footings'},
    {'code':'025', 'description':'CONT. FTGs', 'group':'levels'},
    {'code':'023', 'description':'Trucks', 'group':'footings'}
]

I need to filter out duplicates where the code and the group are duplicates. If only one of them is the same it shouldn't filter it out.

Hi, could you please accept the most fitting answer?

Johannes Jander
– Johannes Jander

2016-01-10 11:19:11 +00:00
Commented Jan 10, 2016 at 11:19 — Johannes Jander
– Johannes Jander, Commented Jan 10, 2016 at 11:19

Community · Accepted Answer · 2017-05-23 11:52:02Z

1

Here is another approach based on TLindig's answer to a similar question.

Add a filter method to the scope:

$scope.onlyUnique = function(value, index, self) { 
  codes = self.map(function(c) {return c.code});
  groups = self.map(function(c) {return c.group});
  return codes.indexOf(value.code) === index || groups.indexOf(value.group) === index;

Call the filter method in your ng-repeat or wherever you want the unique values:

<div ng-repeat="c in SACCodes.filter(onlyUnique)">code: {{c.code}} desc: {{c.description}} group: {{c.group}}</div>

Output:

code: 023 desc: Spread FTGs group: footings
code: 024 desc: Mat FTGs group: footings
code: 025 desc: CONT. FTGs group: footings
code: 025 desc: CONT. FTGs group: levels

edited May 23, 2017 at 11:52

CommunityBot

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answered Jan 9, 2016 at 20:37

Jeremy

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Comments

Blindman67 · Accepted Answer · 2016-01-09 20:52:13Z

1

The ES6 way.

var m = new Map();

SACCodes.forEach ( function( item ) {
    var key = item.code + item.group;
    if ( !m.has( key ) ){
        m.set( key, item );
    }
});
SACCodes= [ ...m.values() ];

answered Jan 9, 2016 at 20:52

Blindman67

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Comments

Johannes Jander · Accepted Answer · 2016-01-09 21:37:29Z

1

This uses a helper hash to note which combination of code and group have already been processed. Only if it finds a hitherto unused combination does it add it to the retVal array;

function dedup() {
    var dups = {};
    var retVal = [];

    for (var i = 0; i < $scope.SACCodes.length; i++) {
       var sCode = $scope.SACCodes[i];
       var key = sCode.code +'/'+ sCode.group;
       if (!dups[key]) {
          retVal.push (sCode);
          dups[key] = sCode;
       }
    }
    return retVal;
}

See working example

Couple of years down the road you could use Object.values(dups); instead of retVal and thereby shorten the code.

edited Jan 9, 2016 at 21:37

answered Jan 9, 2016 at 20:19

Johannes Jander

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