how to sort arrays while ignoring null values in java script

Question

initialArray = [ obj1, obj2, obj3, obj4, obj5, obj6, obj7, obj8 ]; // all eight are uniq objects
filterdArray = [ obj2, obj5, obj6, obj8 ]; // varies from 0 to 8

varOrder = [ 6, 8, 3, 2, 1, 4, 5, 7 ]

I have a varOrder as input, which is from 1 to 8. It is always 1-8 but in different order as per user wish.

Initially the Array have Obj1 to Obj8, but after filter, the Array may or may not have elements, If it has elements, it varies from 1 to 8.

what am I looking for is if

filterdArray = [ obj2, obj5, obj6, obj8 ]; // and my varOrder is
varOrder = [ 6, 8, 3, 2, 1, 4, 5, 7 ]; // required ouput is like below

FinalObjects = [ obj6, obj8, obj2, obj5 ]

In simple, out of 8 in the order give by user, if some objects are not available skip to next object.

The Reasoning for FinalObjects = [ obj6, obj8, obj2, obj5 ] is

varOrder | FilteredArray

6 | obj6 available from FilterdArray (obj6)
8 | obj8 available from FilteredArray (obj8)
3 | obj3 is not available from FilteredArray
2 | obj2 is available from FilteredArray (obj2)
1 | obj1 is not available from FilteredArray
4 | obj4 is not available from FilteredArray
5 | obj5 is available from FilteredArray (obj5)
7 | obj7 is not availabe from FilteredArray

Thus FinalObjects = [ obj6, obj8, obj2, obj5 ]

Please explain the reasoning behind the contents of FinalObjects. — Scott Hunter
– Scott Hunter, Commented Jan 20, 2022 at 19:35
@ScottHunter, 1. varOrder = 6,8,3,2,1,4,5,7 2. filterdArray has obj 2,5,6,8. 3. Match ordernum 6 to obj6. ordernum 8 to obj8 ignore ordernum 3 as obj3 is not available. Match ordernum 2 to obj2 so on. — PRATAP-PANABAKA
– PRATAP-PANABAKA, Commented Jan 20, 2022 at 19:41

Zulfe · Accepted Answer · 2022-01-20 19:39:45Z

2

Perform the mapping first, then filter.

const varOrder = [ 6, 8, 3, 2, 1, 4, 5, 7 ];
const initialArray = [ obj1, obj2, obj3, obj4, obj5, obj6, obj7, obj8 ];

const orderedArray = varOrder.map((idx) => initialArray[idx - 1]);
// [ obj6, obj8, obj3, obj2, obj1, obj4, obj5, obj7 ]

const filteredArray = orderedArray.filter(obj => obj !== null);
// Assume all objects are null except for 6, 8, 2, and 5.
// [ obj6, obj8, obj2, obj5 ]

answered Jan 20, 2022 at 19:39

Zulfe

8819 silver badges25 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

PRATAP-PANABAKA Over a year ago

this is brilliant. It took me hours to understand your code as I am startup learner. It worked and I understood the concept. Thank You.

cmgchess · Accepted Answer · 2022-01-20 19:52:30Z

Hope this is the expected result. just used a for loop

let obj1 = {name: 'obj1'};let obj2 = {name: 'obj2'};let obj3 = {name: 'obj3'};let obj4 = {name: 'obj4'};let obj5 = {name: 'obj5'};let obj6 = {name: 'obj6'};let obj7 = {name: 'obj7'};let obj8 = {name: 'obj8'}

initialArray = [ obj1, obj2, obj3, obj4, obj5, obj6, obj7, obj8 ]; // all eight are uniq objects
filterdArray = [ obj2, obj5, obj6, obj8 ]; // varies from 0 to 8

varOrder1 = [ 6, 3, 8, 2, 1, 4, 5, 7 ];
varOrder2 = [ 7, 5, 4, 1, 2, 8, 3, 6 ];

let finalArr1 = [];
let finalArr2 = [];

const sorter = (varOrder) => {
    let finalArr = []
  for (let i = 0; i < varOrder.length; i++) {
  
    if (filterdArray.includes(initialArray[varOrder[i]-1])){
        finalArr.push(initialArray[varOrder[i]-1])
    }
   }
   return finalArr;
}       

console.log(sorter(varOrder1))

console.log(sorter(varOrder2))

.as-console-wrapper { max-height: 100% !important; top: 0; }

A1exandr Belan · Accepted Answer · 2022-01-21 06:59:17Z

You can use this approach:

First, we map each element of filterdArray to an order index, since this is an expensive operation, and we do not want to run it every time we rearrange the array.

Then we sort the mapped array by the order index.

Finally, we return the original objects.

const initialArray = [{n:'obj1'}, {n:'obj2'}, {n:'obj3'}, {n:'obj4'}, {n:'obj5'}, {n:'obj6'}, {n:'obj7'}, {n:'obj8'}];
const filterdArray = [{n:'obj2'}, {n:'obj5'}, {n:'obj6'}, {n:'obj8'}]; 
const order = [ 6, 8, 3, 2, 1, 4, 5, 7 ];

const mapped = filterdArray.map((obj) => (
  { obj, order: order.at(initialArray.findIndex((item)=> item.n === obj.n)) }));

console.log('mapped >>', mapped);

const sortedByOrder = mapped
  .sort((o1, o2) => o1.order - o2.order)
  .map(({obj}) => obj);
  
console.log('sortedByOrder >>', sortedByOrder);

.as-console-wrapper {max-height: 100% !important; top: 0}

Collectives™ on Stack Overflow

how to sort arrays while ignoring null values in java script

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related