Is there a way to efficiently compare multiple arrays in Typescript and Angular?

Question

Is there a way to efficiently compare multiple arrays in Typescript and Angular?

I am faced with a scenario where I have 4 separate arrays and need to identify if any item appears in more than two of the arrays. If this is the case, I must delete the duplicate items from all arrays except one based on a specific property.

let arrayA = [{id: 1, modifiedOn: 1234}, {id: 2, modifiedOn: 1234}, {id: 3, modifiedOn: 1234}]

let arrayB = [{id: 4, modifiedOn: 1234}, **{id: 2, modifiedOn: 1235}**, {id: 5, modifiedOn: 1234}]

let arrayC = [{id: 6, modifiedOn: 1234}, {id: 7, modifiedOn: 1234},
**{id: 5, modifiedOn: 1235}**

let arrayD = [**{id: 1, modifiedOn: 1235}**, {id: 8, modifiedOn: 1234}, {id: 9, modifiedOn: 1234}]

Upon examining the arrays above, it is clear that ids 2, 5, and 1 are present in more than one array. The rule is to keep the item with the highest value for the modifiedOn property and remove the others.

javascript angular typescript ecmascript-6 ecmascript-2016

Answer 1

Answer №1

https://codepen.io/vitkarpov/pen/GRpZzqx

function creatingSearchIndex(arrays) {
  const index = {};

  for (let i = 0; i < arrays.length; i++) {
    for (let j = 0; j < arrays[i].length; j++) {
      const {id, modifiedOn} = arrays[i][j];
      index[id] = index[id] || {};
      index[id][modifiedOn] = [arrays[i], j];
    }
  }
  return index;
}

function removingDuplicates(...arrays) {
  const searchIndex = creatingSearchIndex(arrays);

  Object.keys(searchIndex).forEach((id) => {
    const index = searchIndex[id];
    const modifiedOnRecords = Object.keys(index);

    // skip first, it corresponds to the value with the smallest modifiedOn value
    for (let i = 1; i < modifiedOnRecords.length; i++) {
      const modifiedOn = modifiedOnRecords[i];
      const [arr, j] = index[modifiedOn];
      arr.splice(j, 1);
    }
  });
}

let arrayX = [{id: 1, modifiedOn: 1234}, {id: 2, modifiedOn: 1234}, {id: 3, modifiedOn: 1234}]
let arrayY = [{id: 4, modifiedOn: 1234}, {id: 2, modifiedOn: 1235}, {id: 5, modifiedOn: 1234}]
let arrayZ = [{id: 6, modifiedOn: 1234}, {id: 7, modifiedOn: 1234}, {id: 5, modifiedOn: 1235}]
let arrayW = [{id: 1, modifiedOn: 1235}, {id: 8, modifiedOn: 1234}, {id: 9, modifiedOn: 1234}]

removingDuplicates(arrayX, arrayY, arrayZ, arrayW);

This problem is quite interesting and would make a great whiteboard interview question!

Answer 2

https://codepen.io/vitkarpov/pen/GRpZzqx

function creatingSearchIndex(arrays) {
  const index = {};

  for (let i = 0; i < arrays.length; i++) {
    for (let j = 0; j < arrays[i].length; j++) {
      const {id, modifiedOn} = arrays[i][j];
      index[id] = index[id] || {};
      index[id][modifiedOn] = [arrays[i], j];
    }
  }
  return index;
}

function removingDuplicates(...arrays) {
  const searchIndex = creatingSearchIndex(arrays);

  Object.keys(searchIndex).forEach((id) => {
    const index = searchIndex[id];
    const modifiedOnRecords = Object.keys(index);

    // skip first, it corresponds to the value with the smallest modifiedOn value
    for (let i = 1; i < modifiedOnRecords.length; i++) {
      const modifiedOn = modifiedOnRecords[i];
      const [arr, j] = index[modifiedOn];
      arr.splice(j, 1);
    }
  });
}

let arrayX = [{id: 1, modifiedOn: 1234}, {id: 2, modifiedOn: 1234}, {id: 3, modifiedOn: 1234}]
let arrayY = [{id: 4, modifiedOn: 1234}, {id: 2, modifiedOn: 1235}, {id: 5, modifiedOn: 1234}]
let arrayZ = [{id: 6, modifiedOn: 1234}, {id: 7, modifiedOn: 1234}, {id: 5, modifiedOn: 1235}]
let arrayW = [{id: 1, modifiedOn: 1235}, {id: 8, modifiedOn: 1234}, {id: 9, modifiedOn: 1234}]

removingDuplicates(arrayX, arrayY, arrayZ, arrayW);

This problem is quite interesting and would make a great whiteboard interview question!

Is there a way to efficiently compare multiple arrays in Typescript and Angular?

Answer №1

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