Ways to retrieve an item from a series of successive arrays

Question

Ways to retrieve an item from a series of successive arrays

I'm struggling to find a solution to my current issue.

My goal is to retrieve the item at a specific index from a collection of separate arrays without merging them together.

Typically, to access the 3rd item in an array, you would use:

function getItemFromJustOneArray(index){
  var my_array = [1,2,3,4,5,6];
  return my_array[index];
}

getItemFromJustOneArray(2); // returns 3

However, my scenario involves multiple arrays that must remain separate and cannot be concatenated.

function getItemFromMultipleArrays(index){

  var array1 = [1,2];
  var array2 = [3,4,5];
  var array3 = [6];

  // I cannot use concat (or similar) to merge the arrays,
  // they need to stay separate
  // it could be any number of arrays, not just three

  // return 3;

}

getItemFromMultipleArrays(2); // SHOULD RETURN 3

I've attempted various methods using loops, but haven't been able to find a viable solution.

If anyone knows of an elegant approach to this problem, I'd greatly appreciate your input.

javascript arrays indexof

Answer 1

Answer №1

To consolidate all arrays within a new array, interweave them. Proceed to iterate over the new array, decreasing the index by the length of each array until it aligns with the size of the current element. Subsequently, you can retrieve the corresponding element from the nested array.

function getItemFromMultipleArrays(index) {

  var array1 = [9, 10];
  var array2 = [11, 12, 13];
  var array3 = [14];
  var all_arrays = [array1, array2, array3];
  var i;
  for (i = 0; i < all_arrays.length && index >= all_arrays[i].length; i++) {
    index -= all_arrays[i].length;
  }
  if (i < all_arrays.length) {
    return all_arrays[i][index];
  }
}

console.log(getItemFromMultipleArrays(1)); // EXPECTED OUTPUT: 12

Answer 2

To consolidate all arrays within a new array, interweave them. Proceed to iterate over the new array, decreasing the index by the length of each array until it aligns with the size of the current element. Subsequently, you can retrieve the corresponding element from the nested array.

function getItemFromMultipleArrays(index) {

  var array1 = [9, 10];
  var array2 = [11, 12, 13];
  var array3 = [14];
  var all_arrays = [array1, array2, array3];
  var i;
  for (i = 0; i < all_arrays.length && index >= all_arrays[i].length; i++) {
    index -= all_arrays[i].length;
  }
  if (i < all_arrays.length) {
    return all_arrays[i][index];
  }
}

console.log(getItemFromMultipleArrays(1)); // EXPECTED OUTPUT: 12

Answer 3

Answer №2

Why not combine multiple arrays into one and use the index to access the value?

function getItemFromMultipleArrays(index) {
    const
        array1 = [1, 2],
        array2 = [3, 4, 5],
        array3 = [6];

    return [...array1, ...array2, ...array3][index];
}

console.log(getItemFromMultipleArrays(2)); // 3

Another method is to use an offset when iterating through arrays.

function getItemFromMultipleArrays(index) {
    const
        array1 = [1, 2],
        array2 = [3, 4, 5],
        array3 = [6],
        temp = [array1, array2, array3];

    let j = 0;

    while (index >= temp[j].length) index -= temp[j++].length;

    return temp[j][index];
}

console.log(getItemFromMultipleArrays(2)); // 3
console.log(getItemFromMultipleArrays(5)); // 6

Answer 4

Why not combine multiple arrays into one and use the index to access the value?

function getItemFromMultipleArrays(index) {
    const
        array1 = [1, 2],
        array2 = [3, 4, 5],
        array3 = [6];

    return [...array1, ...array2, ...array3][index];
}

console.log(getItemFromMultipleArrays(2)); // 3

Another method is to use an offset when iterating through arrays.

function getItemFromMultipleArrays(index) {
    const
        array1 = [1, 2],
        array2 = [3, 4, 5],
        array3 = [6],
        temp = [array1, array2, array3];

    let j = 0;

    while (index >= temp[j].length) index -= temp[j++].length;

    return temp[j][index];
}

console.log(getItemFromMultipleArrays(2)); // 3
console.log(getItemFromMultipleArrays(5)); // 6

Answer 5

Answer №3

By combining all the arrays into one large array, we can easily access elements without altering the original arrays. Below is a snippet of code that demonstrates this concept:

// This function takes multiple arrays as arguments and returns a new concatenated array.
function connectArrays(...arrays) {
  return [...arrays.flat()];
}

// Function to retrieve an item from multiple arrays at a specified index.
function getItemFromMultipleArrays(index) {
  var array1 = [1, 2];
  var array2 = [3, 4, 5];
  var array3 = [6];
  var allArrays = connectArrays(array1, array2, array3);
  
  return allArrays[index];
}

getItemFromMultipleArrays(2); // This should return 3

Answer 6

By combining all the arrays into one large array, we can easily access elements without altering the original arrays. Below is a snippet of code that demonstrates this concept:

// This function takes multiple arrays as arguments and returns a new concatenated array.
function connectArrays(...arrays) {
  return [...arrays.flat()];
}

// Function to retrieve an item from multiple arrays at a specified index.
function getItemFromMultipleArrays(index) {
  var array1 = [1, 2];
  var array2 = [3, 4, 5];
  var array3 = [6];
  var allArrays = connectArrays(array1, array2, array3);
  
  return allArrays[index];
}

getItemFromMultipleArrays(2); // This should return 3

Ways to retrieve an item from a series of successive arrays

Answer №1

Answer №2

Answer №3

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