How to get unique data from rows in javascript

Question

I am trying to get the unique data out of the rows.

My data

name  title
tim    1
tim    1
tim    2
tim    3
time   3
jenny  5
jenny  5
jenny  6
jenny  7

My goal is to display my table using javascript to show

tim    1
tim    2
time   3
jenny  5
jenny  6
jenny  7

I know it's easy to change the data structure or the way to select the data but I don't have the access to the DB so I need to figure out in the javascript

my first step is to push all the unique title to my peopleArray:

The codes I have tried.

 for(var a=0; a<results.length; a++){
        if(results[(a+1)]){
             if(a==0 || results[a].title != results[(a+1)].title){

                peopleArray.push(results[(a)].title)
             }
         }
      }

My codes don't really work and I am stocked here. Anyone has tips for this? Thanks a lot!

create a composite key using a delimiter and push into array and then check array.indexOf(compositeKey) to find if its already pushed. once making a pass through all the rows, pop all the entries in the array and remove the delimiter. — SriN
– SriN, Commented Dec 13, 2012 at 19:37
What is the literal data structure type of your data? Can you post it as json? — Brian Cray
– Brian Cray, Commented Dec 13, 2012 at 19:38
@user711819 javascript doesn't have a native contains. Need to use Array.indexOf(), but if it's an array of dictionaries (objects) then you can't use indexOf either. Would have to do a map first. — Brian Cray
– Brian Cray, Commented Dec 13, 2012 at 19:40
agreed, indexOf(). even if its an array of dicts/objects you can still loop over the objects and construct the compositekeys that can help you to identify unique objects. — SriN
– SriN, Commented Dec 13, 2012 at 19:43
@user711819 Or you could just JSON stringify the objects to get a uniform composite. — user1726343
– user1726343, Commented Dec 13, 2012 at 20:00

Ian · Accepted Answer · 2012-12-13 19:58:25Z

1

For something that does not require the list to be sorted, you can use something like this:

http://jsfiddle.net/4dvfq/1/

var results = [{"name": "tim", "title": "1"},
               {"name": "jenny", "title": "2"},
               {"name": "tim", "title": "1"},
               {"name": "jenny", "title": "1"}];
// Should return "tim 1", "jenny 2", "jenny 1" items

function getUniques(arr) {
    var i = 0;
    var len = arr.length;
    var found = {};
    var ret = [];

    for (; i < len; i++) {
        var cur = arr[i];
        var name = cur.name;
        var title = cur.title;
        var name_title = name + title;

        if (!(name_title in found)) {
            ret.push(cur);
            found[name_title] = 1;
        }
    }
    return ret;
}

console.log(getUniques(results));

edited Dec 13, 2012 at 19:58

answered Dec 13, 2012 at 19:52

Ian

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Comments

Brian Cray · Accepted Answer · 2012-12-13 20:17:30Z

1

If it's already sorted like you have in your question then you can use Array.filter():

data = data.filter(function (d, i) {
    var next = data[i+1] || {name: '', title: ''};
    return d.name != next.name || d.title != next.title;
});

If it's not sorted yet as you have in your question, do this first:

data = data.sort(function (a, b) {
    return a.name < b.name ? -1 : a.name == b.name ? 0 : 1;
});

edited Dec 13, 2012 at 20:17

answered Dec 13, 2012 at 19:44

Brian Cray

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2 Comments

Ian Over a year ago

I think you want ||, not && in the return statement for the filter method

Ian Over a year ago

No problem. I tested it out and it was acting weird :)

score 0 · Accepted Answer · 2012-12-13 19:55:39Z

0

function uniquify(results) {    
    var peopleArray = [];
    for (var a = 0; a < results.length; a++) {
        if (peopleArray.indexOf(JSON.stringify(results[a])) == -1) {
            peopleArray.push(JSON.stringify(results[a]));
        }
    }
    return peopleArray.map(function(val) {
        return JSON.parse(val);
    });
}

This works regardless of sort order and is flexible enough to be used with other schema. Here is a demonstration that uses your data: http://jsfiddle.net/w4cKg/

edited Dec 13, 2012 at 19:55

answered Dec 13, 2012 at 19:42

user1726343

3 Comments

Brian Cray Over a year ago

I don't think you can do .indexOf with an object because you cannot compare objects.

user1726343 Over a year ago

@BrianCray I suspected as much, I was editing my answer. It compares strings now.

Brian Cray Over a year ago

Good approach, but stringifying everything can be a huge performance cost

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