Remove Duplicates from an Array of GeoFire Objects

Problem here is comparing Objects. Two objects are never equal unless both are referencing to same Object.

Example:

{} === {} // false

// Two objects are equal only if they are referencing to same object
var a = {};
a === a; // true

It is clear from your problem that you are facing the first case. Among the solutions you tested Solution 1 and Solution 3 are failing because of this reason as indexOf does === comparision.

But Solution 2 should have worked on your example as it does a deep comparision as explained here. https://lodash.com/docs#isEqual.

PS: It might be a simple typo i have observed in Solution 2 cleaned.,push(itm);, there is an extra comma. Hoping that is not the case I am moving ahead

So i guess the issue is inside your location array, if you can give the contents of location array we should be able to provide better solution. Or as others suggested you can filter based on a single key of the object like id or distance, instead of comparing the whole object

回答3:

You can use following approach:

Idea:

You can create your own data structure and have a hashMap to save values.
Since you have location data, you can use longitude|latitude as your key name as it will be unique.
Then expose some functions say, add that will check if value exists, override else add.
Also create a property, say value that would return the list of locations.

Note: Above behavior can be achieved using Set as well. If you cannot use ES6 features, then this is one way that is extensible and easy.

function MyList() {
  var locations = {};

  this.add = function(value) {
    var key = value.location.join('|');
    locations[key] = value;
  }

  Object.defineProperty(this, 'value', {
    get: function() {
      return Object.keys(locations).map(function(key) {return locations[key] })
    }
  })
}

var locations = new MyList();

locations.add({location: [123.12, 456.23], name: 'test 1' });
locations.add({location: [123.16, 451.23], name: 'test 2' });
locations.add({location: [123.12, 456.23], name: 'test 1' });
locations.add({location: [100.12, 456.23], name: 'test 3' });
locations.add({location: [123.12, 456.23], name: 'test 1' });
locations.add({location: [123.12, 400.23], name: 'test 4' });

console.log(locations.value)

Typescript version for more readability:

interface ILocation {
  location: Array<number>
  [key: string]: any;
}

interface IList {
  [key: string]: ILocation
}

class MyList {
  private locations: IList = {};
  
  public add(value: ILocation) {
    const key: string = value.location.join('|');
    this.locations[key] = value;
  }
  
  public get value(): Array<ILocation> {
    return Object.keys(locations).map(function(key) {return locations[key] })
  }
}

回答4:

uniqWith https://lodash.com/docs/#uniqWith can be used to specify the method to compare by :

var arr = [ { location: [1, 2], distance: "48.84", url: "assets/imgs/fix.png" },
            { location: [1, 2], distance: "48.84", url: "assets/imgs/fix.png" },
            { location: [1, 2], distance: "48.84", url: "assets/imgs/fix.png" },
            { location: [3, 4], distance: "48.85", url: "assets/imgs/free.png"},
            { location: [3, 4], distance: "48.85", url: "assets/imgs/free.png"},
            { location: [3, 4], distance: "48.85", url: "assets/imgs/free.png"},
            { location: [5, 6], distance: "48.87", url: "assets/imgs/low.png" },
            { location: [5, 6], distance: "48.87", url: "assets/imgs/low.png" },
            { location: [5, 6], distance: "48.87", url: "assets/imgs/low.png" } ]
          
var result = _.uniqWith(arr, (a, b) => _.isEqual(a.location, b.location));

console.log( JSON.stringify({...result}).replace(/},/g, '},\n ') );

<script src="https://cdn.jsdelivr.net/npm/lodash@4.17.11/lodash.min.js"></script>

回答5:

You could always check before you add the hits to make sure there are no repeats.

edit: You cannot compare objects unless they have the same reference object. So, you could compare objects by a unique ID

use rxjs filter() this will return an array

// store history of objs for comparison
addedObjs = [];
this.hits.pipe(filter(obj => {
    // check if id is an index of the previous objs
    if (addObjs.indexOf(obj.id) === -1) {
        this.addedObjs.push(obj.id)
        return obj
    });

here is the working stackblitz using some of your code

回答6:

Perhaps you would want to use a library such as lodash which has a wide set of functions regarding all types of collections.

let newArr = _.uniqWith(myArr, _.isEqual);

uniqWith with the help of isEqual can get what you want.

Here is fiddle to that solution

回答7:

I think it is your comparison that may not be working correctly. You can try this:

var uniqueHits = currentHits.reduce((acc, curr) => { 
    if (acc.length === 0) {
        acc.push(curr);
    } else if (!acc.some((item) => 
        item.location[0] === curr.location[0]
        && item.location[1] === curr.location[1]
        && item.distance === curr.distance
        && item.url === curr.url)) {
        acc.push(curr);
    }
    return accumulator;
}, []);;