Instructions for rearranging the configuration of a 2D array?

Question

Instructions for rearranging the configuration of a 2D array?

A 2-dimensional array is created from a string called matrix:

131 673 234 103 018
201 096 342 965 150
630 803 746 422 111
537 699 497 121 956
805 732 524 037 331

After parsing, it becomes an array of arrays like this:

[
  [131, 673, 234, 103, 018],
  [201, 096, 342, 965, 150],
  [630, 803, 746, 422, 111],
  [537, 699, 497, 121, 956],
  [805, 732, 524, 037, 331]
]

But now, the array needs to be restructured to look like this:

[
  [131],
  [201,673],
  [630,096,234],
  [537,803,342,103],
  [805,699,746,965,018],
  [732,497,422,150],
  [524,121,111],
  [037,956],
  [331]
]

This new array follows the up-left diagonals of the string or current array.

The string may need to be manipulated into one line and then rebuilt with newlines in specific positions for the current code to function properly. However, the implementation of this process is not clear at the moment.

The code used to create the array is as follows:

matrix.split("\n").reduce((a, b) =>
{
    a.push(b.split(" ").map(x => parseInt(x)));
    return a;
}, []);

(matrix refers to the variable holding the string)

Ideally, only the reducer function could be replaced to achieve the desired result, but any solution would be greatly appreciated.

javascript arrays

Answer 1

Answer №1

I made some adjustments to your method in order to shift each item of the inner arrays onto the corresponding diagonal. I utilized the Array::unshift() method to add new elements to the beginning of a diagonal array.

const matrix = "131 673 234 103 018\n201 096 342 965 150\n630 803 746 422 111\n537 699 497 121 956\n805 732 524 037 331";

let res = matrix.split("\n").reduce((acc, curr, idx1) =>
{
    curr.split(" ").forEach((n, idx2) =>
    {
        // Determine the index of the diagonal to which this item belongs.
        let dIdx = idx2 + idx1;

        // Add the element to the appropriate diagonal.
        acc[dIdx] = acc[dIdx] || [];
        acc[dIdx].unshift(parseInt(n));
    });

    return acc;

}, []);

console.log(res);

Answer 2

I made some adjustments to your method in order to shift each item of the inner arrays onto the corresponding diagonal. I utilized the Array::unshift() method to add new elements to the beginning of a diagonal array.

const matrix = "131 673 234 103 018\n201 096 342 965 150\n630 803 746 422 111\n537 699 497 121 956\n805 732 524 037 331";

let res = matrix.split("\n").reduce((acc, curr, idx1) =>
{
    curr.split(" ").forEach((n, idx2) =>
    {
        // Determine the index of the diagonal to which this item belongs.
        let dIdx = idx2 + idx1;

        // Add the element to the appropriate diagonal.
        acc[dIdx] = acc[dIdx] || [];
        acc[dIdx].unshift(parseInt(n));
    });

    return acc;

}, []);

console.log(res);

Answer 3

Answer №2

To start, you can navigate from the left side and then proceed to the bottom, moving from left to right and collecting the diagonal values from the array.

function retrieveDiagonalValues(x, y) {
    var result = [];
    while (x >= 0 && y < data[0].length) result.push(data[x--][y++]);
    return result;
}

var data = [[131, 673, 234, 103, 018], [201, 096, 342, 965, 150], [630, 803, 746, 422, 111], [537, 699, 497, 121, 956], [805, 732, 524, 037, 331]],
    result = [],
    i = 0, j = 1;
 
while (i < data.length) result.push(retrieveDiagonalValues(i++, 0));
while (j < data[0].length) result.push(retrieveDiagonalValues(data.length - 1, j++));

console.log(result)

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

Answer 4

To start, you can navigate from the left side and then proceed to the bottom, moving from left to right and collecting the diagonal values from the array.

function retrieveDiagonalValues(x, y) {
    var result = [];
    while (x >= 0 && y < data[0].length) result.push(data[x--][y++]);
    return result;
}

var data = [[131, 673, 234, 103, 018], [201, 096, 342, 965, 150], [630, 803, 746, 422, 111], [537, 699, 497, 121, 956], [805, 732, 524, 037, 331]],
    result = [],
    i = 0, j = 1;
 
while (i < data.length) result.push(retrieveDiagonalValues(i++, 0));
while (j < data[0].length) result.push(retrieveDiagonalValues(data.length - 1, j++));

console.log(result)

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

Answer 5

Answer №3

My approach is as follows:

const input = `131 673 234 103 018
201 096 342 965 150
630 803 746 422 111
537 699 497 121 956
805 732 524 037 331`;

let matrix = input.split('\n').map(line => {
  return line.split(' ').map(elem => parseInt(elem.trim()));
});

let rows = matrix.length,
    cols = matrix[0].length,
    numDiags = rows + cols - 1,
    diagLimit = Math.max(matrix.length, matrix[0].length);

let diagMatrix = [...Array(numDiags)].map((_, diagNum) => {
  let diag = [];
  
  for (let i = 0; i < diagLimit; i++) {
    let r = (diagLimit - 1) - i,
        c = i - (diagLimit - 1) + diagNum;
    
    if (r >= 0 && c >= 0 && r < matrix.length && c < matrix[0].length) {
      diag.push(matrix[r][c]);
    }
  }
  
  return diag;
});

console.log(diagMatrix);

This algorithm loops through each diagonal of length max(rows, cols) within the matrix, including only the elements within the overlapping region. It's designed to accommodate rectangular matrices, allowing for potential optimizations when working with square matrices exclusively.

Answer 6

My approach is as follows:

const input = `131 673 234 103 018
201 096 342 965 150
630 803 746 422 111
537 699 497 121 956
805 732 524 037 331`;

let matrix = input.split('\n').map(line => {
  return line.split(' ').map(elem => parseInt(elem.trim()));
});

let rows = matrix.length,
    cols = matrix[0].length,
    numDiags = rows + cols - 1,
    diagLimit = Math.max(matrix.length, matrix[0].length);

let diagMatrix = [...Array(numDiags)].map((_, diagNum) => {
  let diag = [];
  
  for (let i = 0; i < diagLimit; i++) {
    let r = (diagLimit - 1) - i,
        c = i - (diagLimit - 1) + diagNum;
    
    if (r >= 0 && c >= 0 && r < matrix.length && c < matrix[0].length) {
      diag.push(matrix[r][c]);
    }
  }
  
  return diag;
});

console.log(diagMatrix);

This algorithm loops through each diagonal of length max(rows, cols) within the matrix, including only the elements within the overlapping region. It's designed to accommodate rectangular matrices, allowing for potential optimizations when working with square matrices exclusively.

Answer 7

Answer №4

Check out this handy trick you can utilize. Take a look at the organization of the indices in your matrix:

00  01  02  03

10  11  12

20  21

30

If you observe closely, the sum of indices on each diagonal equals the same number, which corresponds to the index in the resulting array.

You can leverage this insight to easily convert your matrix by implementing the following function:

const convertMatrix = (matrix, rows = matrix.length, cols = matrix[0].length) => {
    const result = [];

    for (let j = 0; j < cols; j++) {
        for (let i = 0; i < rows; i++) {
            const index = i + j; // this will be the resulting index
            if (index >= result.length) result[index] = []; // dynamically create new rows
            result[index].push(matrix[i][j]);
        }
    }

    return result;
};

console.log(JSON.stringify(convertMatrix([ [131, 673, 234, 103,  18]
                                     , [201,  96, 342, 965, 150]
                                     , [630, 803, 746, 422, 111]
                                     , [537, 699, 497, 121, 956]
                                     , [805, 732, 524,  37, 331]
                                     ])));

I hope you find this information useful.

Answer 8

Check out this handy trick you can utilize. Take a look at the organization of the indices in your matrix:

00  01  02  03

10  11  12

20  21

30

If you observe closely, the sum of indices on each diagonal equals the same number, which corresponds to the index in the resulting array.

You can leverage this insight to easily convert your matrix by implementing the following function:

const convertMatrix = (matrix, rows = matrix.length, cols = matrix[0].length) => {
    const result = [];

    for (let j = 0; j < cols; j++) {
        for (let i = 0; i < rows; i++) {
            const index = i + j; // this will be the resulting index
            if (index >= result.length) result[index] = []; // dynamically create new rows
            result[index].push(matrix[i][j]);
        }
    }

    return result;
};

console.log(JSON.stringify(convertMatrix([ [131, 673, 234, 103,  18]
                                     , [201,  96, 342, 965, 150]
                                     , [630, 803, 746, 422, 111]
                                     , [537, 699, 497, 121, 956]
                                     , [805, 732, 524,  37, 331]
                                     ])));

I hope you find this information useful.

Instructions for rearranging the configuration of a 2D array?

Answer №1

Answer №2

Answer №3

Answer №4

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