Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Group values in array by two properties JavaScript
We have an array of objects like this −
const arr = [
{ value: 12, gap: 1 },
{ value: 13, gap: 1 },
{ value: 14, gap: 1 },
{ value: 15, gap: 1 },
{ value: 19, gap: 2 },
{ value: 21, gap: 1 },
{ value: 22, gap: 1 },
{ value: 23, gap: 1 },
{ value: 27, gap: 1 },
{ value: 31, gap: 4 },
{ value: 35, gap: 4 },
{ value: 39, gap: 4 },
{ value: 43, gap: 1 },
{ value: 50, gap: 1 },
{ value: 51, gap: 1 },
{ value: 52, gap: 1 },
{ value: 55, gap: 1 },
{ value: 57, gap: 1 },
];We are required to write a function that takes in this array and returns a new array where all those consecutive objects whose value is equal to the sum of previous object’s value and gap must be grouped together in a subarray.
For example − The object with value 12 has gap 1 and its next object has value 13, so they must be grouped and with them the object with value 14 and 15, and like this.
Now, with the problem understood, let’s move on to writing the code for this problem. We will use Array.prototype.reduce() method to construct the desired array −
Example
const arr = [
{ value: 12, gap: 1 },
{ value: 13, gap: 1 },
{ value: 14, gap: 1 },
{ value: 15, gap: 1 },
{ value: 19, gap: 2 },
{ value: 21, gap: 1 },
{ value: 22, gap: 1 },
{ value: 23, gap: 1 },
{ value: 27, gap: 1 },
{ value: 31, gap: 4 },
{ value: 35, gap: 4 },
{ value: 39, gap: 4 },
{ value: 43, gap: 1 },
{ value: 50, gap: 1 },
{ value: 51, gap: 1 },
{ value: 52, gap: 1 },
{ value: 55, gap: 1 },
{ value: 57, gap: 1 },
];
const groupArray = arr => {
return arr.reduce((acc, val, ind, array) => {
// the accumulated data and lastIndex of accumulated data
const { data, currentIndex } = acc;
// the current object properties
const { value, gap } = val;
// the previous object properties
const v = arr[ind-1]?.value;
const g = arr[ind-1]?.gap;
if(ind === 0 || value !== v + g){
// recording the index of last object and pushing new subarray
const index = data.push([val]) - 1;
return { data, currentIndex: index };
};
data[currentIndex].push(val);
return { data, currentIndex };
}, {
data: [],
currentIndex: 0
}).data;
}
console.log(groupArray(arr));Output
The output in the console will be −
[
[
{ value: 12, gap: 1 },
{ value: 13, gap: 1 },
{ value: 14, gap: 1 },
{ value: 15, gap: 1 }
],
[
{ value: 19, gap: 2 },
{ value: 21, gap: 1 },
{ value: 22, gap: 1 },
{ value: 23, gap: 1 }
],
[ { value: 27, gap: 1 } ],
[
{ value: 31, gap: 4 },
{ value: 35, gap: 4 },
{ value: 39, gap: 4 },
{ value: 43, gap: 1 }
],
[
{ value: 50, gap: 1 },
{ value: 51, gap: 1 },
{ value: 52, gap: 1 }
],
[ { value: 55, gap: 1 } ],
[ { value: 57, gap: 1 } ]
]
Updated on: 25-Aug-2020
826 Views
Advertisements