Transform javascript object's values to remove duplicates inside array

Question

I have a Javascript object (of indefinite size) where the value is an array of strings. For example :

var obj =  {
    "article1": ["john locke", "sawyer", "john Locke"] ,
    "article2": ["person3", "person4"] 
}

I want to transform so that any duplicate string is removed.

That means for the example above, I'd have

var finalObj =  {
    "article1": ["john locke", "sawyer"], //"john Locke" was removed"
    "article2": ["person3", "person4"] 
}

It has to be case insensitive, i.e john Locke should be removed if there is already at the start 'john locke".

How to achieve this ?

well objects do not have a map, arrays do. So means you are trying to use map on the object, not the arrays in the object, — epascarello
– epascarello, Commented Sep 11, 2019 at 12:53
I know i edited my question: i'm a beginner : with array i'd know how to do using .map but here i don't manage...tried some .reduce() but did not succeed — Mathieu
– Mathieu, Commented Sep 11, 2019 at 12:54
so you need to change the case? since "john locke" !== "john Locke" — epascarello
– epascarello, Commented Sep 11, 2019 at 12:57
what is desired result for this ["john Locke", "john locke", "sawyer"], should the case of first occurrence of value to be maintained in output ? — Code Maniac
– Code Maniac, Commented Sep 11, 2019 at 13:02

epascarello · Accepted Answer · 2019-09-11 13:01:55Z

2

So first loop over the keys, than dedupe the arrays using a set. Since it seems case does not matter the array needs to be lowerCased before it is used in a set.

var obj = {
  "article1": ["john locke", "sawyer", "john Locke"],
  "article2": ["person3", "person4"]
}

var finalObj = Object.entries(obj).reduce((o, [key, arr]) => {
  o[key] = [...new Set(arr.map(t => t.toLowerCase()))]
  return o
}, {})

console.log(finalObj)

answered Sep 11, 2019 at 13:01

epascarello

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Comments

Code Maniac · Accepted Answer · 2019-09-11 12:56:11Z

You can use for...in and reduce

Loop through object using for ... in
For each key, loop through respective array,
Change input value to lowercase and check if it is already in includes property or not, if it is not there than update final with current value and add that key into the includes property as true
at the end return final and assign it to key of object

let obj = {
  "article1": ["john locke", "sawyer", "john Locke"],
  "article2": ["person3", "person4"]
}

let removeDuplicate = (arr) => {
  let output = arr.reduce((op, inp) => {
    let key = inp.toLowerCase()
    if (!op.includes[key]) {
      op.final.push(inp)
      op.includes[key] = true
    }
    return op
  }, { includes: {}, final: [] })
  return output.final
}

for (let key in obj) {
  obj[key] = removeDuplicate(obj[key])
}

console.log(obj)

Nicolae Maties · Accepted Answer · 2019-09-11 12:58:07Z

1

You can use new Set() but before that you need to take care of the insensitive cases, like lock Lock.

const obj =  {
      "article1": ["john locke", "sawyer", "john Locke"],
      "article2": ["person3", "person4"] 
 };


 // this is for all the fields that are array ( will have unique elements )
 for(let key in obj){
  if(Array.isArray(obj[key])){
    obj[key] = obj[key].map(el => el.toLowerCase());
    obj[key] = [...new Set(obj[key])];
  }
 }
 
 console.log(obj)

answered Sep 11, 2019 at 12:58

Nicolae Maties

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Comments

Krzysztof · Accepted Answer · 2019-09-11 12:58:16Z

0

Here is example code:

Object.keys(obj)
    .forEach(function (k) {
        var dict = {};
        obj[k].forEach(function (v, i) {
            v = v.toLowerCase(); // make value lower case since "john locke"!="john Locke"
            if (dict[v]) {
                obj[k].splice(i, 1);
            }
            dict[v] = true;
        });
    });

Note that this code modifies object obj and inner arrays.

answered Sep 11, 2019 at 12:58

Krzysztof

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Comments

Mischa · Accepted Answer · 2019-09-11 13:00:42Z

0

For every attr in Obj: 1. map the array to lowercase values 2. filter duplicates

var obj =  {
    "article1": ["john locke", "sawyer", "john Locke"],
    "article2": ["person3", "person4"] 
}

var newObj = {}

for(let attr in obj) {
    newObj[attr] = obj[attr].map(item => item.toLowerCase())
        .filter((item, idx, arr) => arr.indexOf(item) === idx)
}

console.log(newObj);

answered Sep 11, 2019 at 13:00

Mischa

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Abhisar Tripathi · Accepted Answer · 2019-09-11 13:07:21Z

0

This will work -:

let obj = {
    article1: ["john locke", "sawyer", "john Locke"], 
    article2: ["person3", "person4"] 
};

var finalObj = Object.keys(obj).reduce((acc, key) => {
  let uniqueArr = obj[key].map(i => i.toLowerCase()).filter((item, pos) =>            obj[key].indexOf(item.toLowerCase()) == pos); 
 return {...acc, [key]: uniqueArr};
}, {});

console.log(finalObj)

edited Sep 11, 2019 at 13:07

answered Sep 11, 2019 at 12:59

Abhisar Tripathi

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Comments

LiuXiMin · Accepted Answer · 2019-09-11 13:09:30Z

0

Using for ... in, set, map and Array.from:

var obj =  {
    "article1": ["john locke", "sawyer", "john Locke"] ,
    "article2": ["person3", "person4"] 
}
var newObj = {}
for (let k in obj){
    newObj[k] =  Array.from(new Set(obj[k].map((i) => i.toLowerCase())))
}

console.log(newObj)

answered Sep 11, 2019 at 13:09

LiuXiMin

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