Operation to remove objects equal to array value

Question

I have an object array and a normal array, and if an item in the object array is equal to an item in the normal array, I want to remove it. This is confusing to me.

Here's what I've tried so far:

<code>var countries =
[
{ChoicesID: ​​1, ChoicesName : 'afghanistan'},
{ChoicesID: ​​2, ChoicesName : 'albania'},
{ChoicesID: ​​3, ChoicesName : 'algeria'},
{ChoicesID: ​​4, ChoicesName : 'angola'},
{ChoicesID: ​​5, ChoicesName : 'argentina'},
{ChoicesID: ​​6, ChoicesName : 'armenia'}
];

var answer = ['afghanistan','albania','algeria'];

var ChoicesName = new Set(countries.map(d => d.ChoicesName));
var NewCountries = [...ChoicesName, ...answer.filter(d => !ChoicesName.has(countries.find(o => o.ChoicesName === answer)))];
console.log(NewCountries );</code>

The expected output should look like this:

var NewCountries =
     [
       {ChoicesID: ​​4, ChoicesName : 'angola'},
       {ChoicesID: ​​5, ChoicesName : 'argentina'},
       {ChoicesID: ​​6, ChoicesName : 'armenia'}
     ];

Answer 1

var countries = 
[
{ChoicesID: 1, ChoicesName : '阿富汗'},
{ChoicesID: 2, ChoicesName : '阿尔巴尼亚'},
{ChoicesID: 3, ChoicesName : '阿尔及利亚'},
{ChoicesID: 4, ChoicesName : '安哥拉'},
{ChoicesID: 5, ChoicesName : '阿根廷'},
{ChoicesID: 6, ChoicesName : '亚美尼亚'}
];

var answer = ['阿富汗','阿尔巴尼亚','阿尔及利亚'];

var NewCountries = countries.filter(o => !answer.includes(o.ChoicesName))

console.log(NewCountries)

like this?

Answer 2

Use filter and remove if it exists in answer. Create an answerSet for O(1) lookup, otherwise includes can be used, but the time complexity of includes is O(m) (where m is answer The number of elements in the array, n is countries The number of elements in the array)

Use set
O(m) O(n).O(1) = O(n) (given n>m)

Use includes
O(n).O(m) = O(nm)

var countries = [{ChoicesID: 1, ChoicesName : 'afghanistan'},{ChoicesID: 2, ChoicesName : 'albania'},{ChoicesID: 3, ChoicesName : 'algeria'},{ChoicesID: 4, ChoicesName : 'angola'},{ChoicesID: 5, ChoicesName : 'argentina'},{ChoicesID: 6, ChoicesName : 'armenia'}];
var answer = ['afghanistan','albania','algeria'];

const answerSet = new Set(answer)

const newCountries = countries.filter(c => !answerSet.has(c.ChoicesName))

console.log(newCountries)