Comes equipped with functionality for array within an array

Question

Comes equipped with functionality for array within an array

I have an array of arrays.

m = [[-100,100], [-100,-100], [-100,-100], [-100,100]]

Removing duplicates in this array has proven tricky for me. I attempted to use:

 aa = [...new Set(m)];

// and 

let chkdup = (arr, tar) => tar.every(v => arr.includes(v))`.

Unfortunately, I was not successful in removing the duplicates using these methods.

In Python, checking for duplicates is straightforward with [-100,100] in m. However, I am unsure of the equivalent function in JavaScript. The includes method does not seem to work in this case.

javascript arrays

Answer 1

Answer №1

The reason behind this issue is that [-100, 100] != [-100, 100]. To resolve this, one approach is to convert the arrays into strings and then compare the strings using JSON.stringify.

let arr = [[-100,100], [-100,-100], [-100,-100], [-100,100]]
arr = arr.map(item => JSON.stringify(item).trim()) // Convert to string format
arr = [...new Set(arr)] // Remove duplicates by converting to array
arr = arr.map(item => JSON.parse(item)) // Parse back to objects

It's important to note that while this solution may not be the most efficient (due to the need for converting to and from strings), it is a straightforward method. This comparison method works specifically with comparing the JSON strings of two objects and will not function properly with custom classes.

Answer 2

The reason behind this issue is that [-100, 100] != [-100, 100]. To resolve this, one approach is to convert the arrays into strings and then compare the strings using JSON.stringify.

let arr = [[-100,100], [-100,-100], [-100,-100], [-100,100]]
arr = arr.map(item => JSON.stringify(item).trim()) // Convert to string format
arr = [...new Set(arr)] // Remove duplicates by converting to array
arr = arr.map(item => JSON.parse(item)) // Parse back to objects

It's important to note that while this solution may not be the most efficient (due to the need for converting to and from strings), it is a straightforward method. This comparison method works specifically with comparing the JSON strings of two objects and will not function properly with custom classes.

Answer 3

Answer №2

One reason why new Set may not work as expected is due to the fact that in JavaScript, arrays with identical values are not considered equal. For example, running

console.log([-100,100] == [-100,100]);

will return false. If you need assistance comparing arrays, you can check out this helpful post.

An effective workaround involves converting subarrays into strings and then leveraging Set for deduplication:

const arr = [
  [-100, 100],
  [-100, -100],
  [-100, -100],
  [-100, 100]
];

const setArray = new Set(arr.map(x => JSON.stringify(x)));

const result = [...setArray].map(x => JSON.parse(x));

console.log(result);

If you're looking for a simpler solution, using Lodash uniq could be a viable option.

Answer 4

One reason why new Set may not work as expected is due to the fact that in JavaScript, arrays with identical values are not considered equal. For example, running

console.log([-100,100] == [-100,100]);

will return false. If you need assistance comparing arrays, you can check out this helpful post.

An effective workaround involves converting subarrays into strings and then leveraging Set for deduplication:

const arr = [
  [-100, 100],
  [-100, -100],
  [-100, -100],
  [-100, 100]
];

const setArray = new Set(arr.map(x => JSON.stringify(x)));

const result = [...setArray].map(x => JSON.parse(x));

console.log(result);

If you're looking for a simpler solution, using Lodash uniq could be a viable option.

Answer 5

Answer №3

Using JavaScript, you can achieve this by utilizing the Set and map functions to parse the value. For further details, refer to this article on Map with Set.

 m = [[-100,100], [-100,-100], [-100,-100], [-100,100]];
 result = Array.from(new Set(m.map(JSON.stringify)), JSON.parse);
 console.log(t);

Answer 6

Using JavaScript, you can achieve this by utilizing the Set and map functions to parse the value. For further details, refer to this article on Map with Set.

 m = [[-100,100], [-100,-100], [-100,-100], [-100,100]];
 result = Array.from(new Set(m.map(JSON.stringify)), JSON.parse);
 console.log(t);

Answer 7

Answer №4

To transform arrays into strings, use the .map() method with JSON.stringify(), then input them into a set. By converting the array elements into strings, the set can effectively eliminate duplicates by comparing for equality. Next, utilize Array.from with a mapping function of JSON.parse to revert it back into an array of arrays:

const arr = [[-100,100], [-200,-200], [-100,-150], [-175,125]];
const result = Array.from(new Set(arr.map(JSON.stringify)), JSON.parse);
console.log(result);

Answer 8

To transform arrays into strings, use the .map() method with JSON.stringify(), then input them into a set. By converting the array elements into strings, the set can effectively eliminate duplicates by comparing for equality. Next, utilize Array.from with a mapping function of JSON.parse to revert it back into an array of arrays:

const arr = [[-100,100], [-200,-200], [-100,-150], [-175,125]];
const result = Array.from(new Set(arr.map(JSON.stringify)), JSON.parse);
console.log(result);

Comes equipped with functionality for array within an array

Answer №1

Answer №2

Answer №3

Answer №4

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