Rearrange an irregular matrix using JavaScript

Question

Rearrange an irregular matrix using JavaScript

I have a matrix that can vary in width depending on the results received from the server. Here is an example:

[undefined, undefined]
[1, 2, 3, 4]
[1, 2]
[undefined, undefined, undefined]
[1, 2, 3, 4, 5, 6]

My goal is to transform it into this format:

[undefined, 1, 1, undefined, 1]
[undefined, 2, 2, undefined, 2]
[undefined, 3, undefined, undefined, 3]
[undefined, 4, undefined, undefined, 4]
[undefined, undefined, undefined, undefined, 5]
[undefined, undefined, undefined, undefined, 6]

The height of the matrix should match the maximum width of the initial example. I tried using the code snippet I found online:

array.map((row, i) => array.map(col => col[i]))

However, this solution does not change the height of my matrix. I attempted to use two for loops but did not achieve the desired outcome. Any assistance would be greatly appreciated!

javascript arrays matrix

Answer 1

Answer №1

There are various methods to tackle this issue, as seen in other responses. Below is my approach, focused on reducing the number of iterations over the data set.

const data = [
  [undefined, undefined],
  [1, 2, 3, 4],
  [1, 2],
  [undefined, undefined, undefined],
  [1, 2, 3, 4, 5, 6],
];

// Determine the length of the longest array
const maxLen = data.reduce((max, {length}) => Math.max(max, length), 0);

// Create a new set of arrays
const result = Array.from({ length: maxLen }, (_, i) => data.map(col => col[i]));

console.log(result);

Answer 2

There are various methods to tackle this issue, as seen in other responses. Below is my approach, focused on reducing the number of iterations over the data set.

const data = [
  [undefined, undefined],
  [1, 2, 3, 4],
  [1, 2],
  [undefined, undefined, undefined],
  [1, 2, 3, 4, 5, 6],
];

// Determine the length of the longest array
const maxLen = data.reduce((max, {length}) => Math.max(max, length), 0);

// Create a new set of arrays
const result = Array.from({ length: maxLen }, (_, i) => data.map(col => col[i]));

console.log(result);

Answer 3

Answer №2

If your matrix is stored in the variable matrix,

const result = [];

const maxColumns = matrix.reduce((max, current) => {
    return (current.length > max) ? current.length : max;
}, 0);

// Iterating through each column
for (let i = 0; i < maxColumns; i++) {
    const transposedRow = [];

    // Iterating through each row in the current column
    for (const row of matrix) {
        transposedRow.push(row[i]);
    }

    result.push(transposedRow);
}

Answer 4

If your matrix is stored in the variable matrix,

const result = [];

const maxColumns = matrix.reduce((max, current) => {
    return (current.length > max) ? current.length : max;
}, 0);

// Iterating through each column
for (let i = 0; i < maxColumns; i++) {
    const transposedRow = [];

    // Iterating through each row in the current column
    for (const row of matrix) {
        transposedRow.push(row[i]);
    }

    result.push(transposedRow);
}

Answer 5

Answer №3

To achieve the desired outcome, follow these steps.

Determine the maximum length.
Normalize the data.
Proceed with rotation.

Code comments have been included to highlight each segment of the process.

const input = [
  [undefined, undefined],
  [1, 2, 3, 4],
  [1, 2],
  [undefined, undefined, undefined],
  [1, 2, 3, 4, 5, 6]
];

// Find the maximum length
const maxLength = Math.max(...input.map(m => m.length));

// Normalize the input array
const normalizedInputs = input.map(m => 
  (new Array(maxLength)).concat(m).slice(-maxLength)
);

// Perform rotation on the normalized data
const output = (new Array(maxLength).fill(0)).map(
  (row, i) => normalizedInputs.map(col => col[i])
);

Answer 6

To achieve the desired outcome, follow these steps.

Determine the maximum length.
Normalize the data.
Proceed with rotation.

Code comments have been included to highlight each segment of the process.

const input = [
  [undefined, undefined],
  [1, 2, 3, 4],
  [1, 2],
  [undefined, undefined, undefined],
  [1, 2, 3, 4, 5, 6]
];

// Find the maximum length
const maxLength = Math.max(...input.map(m => m.length));

// Normalize the input array
const normalizedInputs = input.map(m => 
  (new Array(maxLength)).concat(m).slice(-maxLength)
);

// Perform rotation on the normalized data
const output = (new Array(maxLength).fill(0)).map(
  (row, i) => normalizedInputs.map(col => col[i])
);

Answer 7

Answer №4

Here is a more effective approach:

const calculateMaxLength = (arr) => {
  let maxVal = 0

  for (const { length } of arr) maxVal = Math.max(maxVal, length)

  return maxVal
}

const transposeArray = (array, placeholder = undefined) => {
  const result = []
  const maxLength = calculateMaxLength(array)
  let row = 0

  for (const { length } = array; row < length; row++) {
    const innerArr = array[row]
    let col = 0

    for (const { length } = innerArr; col < length; col++) {
      result[col] ||= []
      result[col].push(innerArr[col])
    }

    for (; col < maxLength; col++) {
      result[col] ||= []
      result[col].push(placeholder)
    }
  }

  return result
}

const transposedArray = transposeArray(
  [
    [1, 2],
    ['a', 'b', 'c', 'd'],
  ]
)

console.log('Transposed Array:', transposedArray)

console.log('Original Array after Transposing back:', transposeArray(transposedArray))

Answer 8

Here is a more effective approach:

const calculateMaxLength = (arr) => {
  let maxVal = 0

  for (const { length } of arr) maxVal = Math.max(maxVal, length)

  return maxVal
}

const transposeArray = (array, placeholder = undefined) => {
  const result = []
  const maxLength = calculateMaxLength(array)
  let row = 0

  for (const { length } = array; row < length; row++) {
    const innerArr = array[row]
    let col = 0

    for (const { length } = innerArr; col < length; col++) {
      result[col] ||= []
      result[col].push(innerArr[col])
    }

    for (; col < maxLength; col++) {
      result[col] ||= []
      result[col].push(placeholder)
    }
  }

  return result
}

const transposedArray = transposeArray(
  [
    [1, 2],
    ['a', 'b', 'c', 'd'],
  ]
)

console.log('Transposed Array:', transposedArray)

console.log('Original Array after Transposing back:', transposeArray(transposedArray))

Rearrange an irregular matrix using JavaScript

Answer №1

Answer №2

Answer №3

Answer №4

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