Creating a fresh array by selecting specific elements at a desired index from an array of arrays

Question

Creating a fresh array by selecting specific elements at a desired index from an array of arrays

Consider the following scenario in JavaScript:

data = [[5,3,2],[2,7,4],[4,6,3],[2,6,4]]

An idea is to create a function that can take an array and an index as inputs, and then return a new array consisting of only the values at that specific index from each sub-array.

For instance:

result = customFunction(data, 1);

//expected outcome: result = [3,7,6,6]

Is there an efficient and effective way to achieve this objective?

javascript arrays

Answer 1

Answer №1

Give this a shot:

Here's a helpful function to filter out indexes from a two-dimensional array: 

function filterIndexes(2dArray, index) {
    return 2dArray.map(function(subarray) {
         return subarray[index];
    });
}

Answer 2

Give this a shot:

Here's a helpful function to filter out indexes from a two-dimensional array: 

function filterIndexes(2dArray, index) {
    return 2dArray.map(function(subarray) {
         return subarray[index];
    });
}

Answer 3

Answer №2

let numbers = [
  [7, 2, 9],
  [1, 5, 8],
  [3, 6, 4],
  [2, 4, 5]
]

const extractColumn = function(arr, index) {
  return arr.map(element => element[index]);
}

const extractedResult = extractColumn(numbers, 1)

console.log(extractedResult)

Answer 4

let numbers = [
  [7, 2, 9],
  [1, 5, 8],
  [3, 6, 4],
  [2, 4, 5]
]

const extractColumn = function(arr, index) {
  return arr.map(element => element[index]);
}

const extractedResult = extractColumn(numbers, 1)

console.log(extractedResult)

Answer 5

Answer №3

It's important to remember that arrays are zero-based in your example. Therefore, for index 2, the correct answer is [2, 4, 3, 4]

The function can be written as follows:

const foo = [[5,3,2],[2,7,4],[4,6,3],[2,6,4]];

function bar(arr, index) {
    return arr.map( subarray => subarray[index] );
}

console.log( bar( foo, 2 ) );

A shorter alternative version would be:

const foo = [[5,3,2],[2,7,4],[4,6,3],[2,6,4]];
const bar = (arr, index) => arr.map( subarray => subarray[index] );

console.log( bar ( foo, 2 ) );

Answer 6

It's important to remember that arrays are zero-based in your example. Therefore, for index 2, the correct answer is [2, 4, 3, 4]

The function can be written as follows:

const foo = [[5,3,2],[2,7,4],[4,6,3],[2,6,4]];

function bar(arr, index) {
    return arr.map( subarray => subarray[index] );
}

console.log( bar( foo, 2 ) );

A shorter alternative version would be:

const foo = [[5,3,2],[2,7,4],[4,6,3],[2,6,4]];
const bar = (arr, index) => arr.map( subarray => subarray[index] );

console.log( bar ( foo, 2 ) );

Answer 7

Answer №4

A potential solution could involve looping through the array and creating a new one:

foo = [[5,3,2],[2,7,4],[4,6,3],[2,6,4]]
function bar(arr, idx) {
   var selectedArr = [];
   arr.forEach(function(subArr) {
     selectedArr.push(subArr[idx]);
   });
   return selectedArr;
}


document.getElementById("result").innerText = bar(foo,2);

<span id="result"></span>

Answer 8

A potential solution could involve looping through the array and creating a new one:

foo = [[5,3,2],[2,7,4],[4,6,3],[2,6,4]]
function bar(arr, idx) {
   var selectedArr = [];
   arr.forEach(function(subArr) {
     selectedArr.push(subArr[idx]);
   });
   return selectedArr;
}


document.getElementById("result").innerText = bar(foo,2);

<span id="result"></span>

Creating a fresh array by selecting specific elements at a desired index from an array of arrays

Answer №1

Answer №2

Answer №3

Answer №4

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