Combining rows using a specific column in Javascript

Question

Combining rows using a specific column in Javascript

Could this particular question already be in existence, but just hasn't been found yet? Is there a method for consolidating multiple values into one row of a 2D array with x rows and 2 columns based on them sharing the same element in the first column?

[['Needs Work', 'Joe'], ['Needs Work', 'Jill'], ['Needs Work', 'Jack'], ['Complete', 'Sean'], ['Complete', 'Joe'], ['Not Started', 'Laura'], ['Needs Work', 'Jack']]

The desired output should resemble:

[ [ 'Needs Work', 'Joe,Jill,Jack,Jack' ],
  [ 'Complete', 'Sean,Joe' ],
  [ 'Not Started', 'Laura' ] ]

javascript arrays

Answer 1

Answer №1

It's puzzling if this is the most optimum approach.

function myFunction() {
  var array = [['Needs Work', 'Joe'], ['Needs Work', 'Jill'], ['Needs Work', 'Jack'], ['Complete', 'Sean'], ['Complete', 'Joe'], ['Not Started', 'Laura'], ['Needs Work', 'Jack']];
  const extractColumn = (arr, n) => arr.map(row => row[n])
  var list = [...new Set(extractColumn(array, 0))]//acquires unique values from first column
  // console.log(list)
  var condensedArray = []
  for (var i = 0; i < list.length; i++) {
    var filteredArray = array.filter(row => row[0] == list[i])//narrows down array to current value
    // console.log(filteredArray)
    condensedArray.push([list[i], extractColumn(filteredArray, 1).toString()])

  }
  console.log(condensedArray)
}

Answer 2

It's puzzling if this is the most optimum approach.

function myFunction() {
  var array = [['Needs Work', 'Joe'], ['Needs Work', 'Jill'], ['Needs Work', 'Jack'], ['Complete', 'Sean'], ['Complete', 'Joe'], ['Not Started', 'Laura'], ['Needs Work', 'Jack']];
  const extractColumn = (arr, n) => arr.map(row => row[n])
  var list = [...new Set(extractColumn(array, 0))]//acquires unique values from first column
  // console.log(list)
  var condensedArray = []
  for (var i = 0; i < list.length; i++) {
    var filteredArray = array.filter(row => row[0] == list[i])//narrows down array to current value
    // console.log(filteredArray)
    condensedArray.push([list[i], extractColumn(filteredArray, 1).toString()])

  }
  console.log(condensedArray)
}

Answer 3

Answer №2

Based on the answer you provided, I came up with the following function:

function generateUnionArray(initialArray) {
  const temporaryObject = {};
  for (let i in initialArray) {
    const workState = initialArray[i][0];
    const peopleName = initialArray[i][1];
    if (temporaryObject[workState] === undefined) {
      temporaryObject[workState] = [peopleName];
    } else {
      temporaryObject[workState].push(peopleName);
    }
  }
  const outputArray = [];
  let iteration = 0;
  for (let i in temporaryObject) {
    outputArray[iteration] = [i, temporaryObject[i]];
    iteration++;
  }
  return outputArray;
}

Unlike your approach, my function returns the names in an array rather than a concatenated string. This can be more useful if you need to manipulate the names individually later on.

Answer 4

Based on the answer you provided, I came up with the following function:

function generateUnionArray(initialArray) {
  const temporaryObject = {};
  for (let i in initialArray) {
    const workState = initialArray[i][0];
    const peopleName = initialArray[i][1];
    if (temporaryObject[workState] === undefined) {
      temporaryObject[workState] = [peopleName];
    } else {
      temporaryObject[workState].push(peopleName);
    }
  }
  const outputArray = [];
  let iteration = 0;
  for (let i in temporaryObject) {
    outputArray[iteration] = [i, temporaryObject[i]];
    iteration++;
  }
  return outputArray;
}

Unlike your approach, my function returns the names in an array rather than a concatenated string. This can be more useful if you need to manipulate the names individually later on.

Combining rows using a specific column in Javascript

Answer №1

Answer №2

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