如何删除对象数组中出现多次的任何对象? [英] How to remove any objects that appear more than once in an array of objects?

问题描述

如果我有一个像这样的数组:

  [{编号:1标题:'foo'}，{编号:2标题栏'}，{id:3，标题:蝙蝠"}，{编号:4标题:"bantz"}，{编号:2标题栏'}，{id:3，标题:蝙蝠"}] 

我想返回一个数组，其中包含仅出现一次的所有对象.因此，对于此示例，所需的输出将是:

  [{编号:1标题:'foo'}，{编号:4标题:"bantz"}] 

我尝试了几种使用 reduce()和 indexOf()来解决此问题的方法，例如解决方案

您可以使用 Map 来避免不得不一次又一次地浏览数组，这将导致效率低下的 O(n²)时间复杂度.这是 O(n):

  function getUniquesOnly(data){返回Array.from(data.reduce((acc，o)=> acc.set(o.id，acc.has(o.id)?0:o)，新Map)，(([[k，v])=> v)).filter(x => x);}var数据= [{编号:1标题:'foo'}，{编号:2标题栏'}，{id:3，标题:蝙蝠"}，{编号:4标题:"bantz"}，{编号:2标题栏'}，{id:3，标题:蝙蝠"}];console.log(getUniquesOnly(data));  

If I have an array like:

[
    {
        id: 1,
        title: 'foo'
    },
    {
        id: 2,
        title: 'bar'
    },
    {
        id: 3,
        title: 'bat'
    },
    {
        id: 4,
        title: 'bantz'
    },
    {
        id: 2,
        title: 'bar'
    },
    {
        id: 3,
        title: 'bat'
    }
]

And I want to return an array that contains any objects that appear only once. So for this example, the desired output would be:

[
    {
        id: 1,
        title: 'foo'
    },
    {
        id: 4,
        title: 'bantz'
    }
]

I have tried a few different approaches that I have found to solve this using reduce() and indexOf(), like this solution, but they do not work with objects for some reason.

Any assistance would be greatly appreciated.

解决方案

You could use a Map to avoid having to look through the array again and again, which would lead to inefficient O(n²) time-complexity. This is O(n):

function getUniquesOnly(data) {
    return Array.from(
        data.reduce( (acc, o) => acc.set(o.id, acc.has(o.id) ? 0 : o), new Map),
        (([k,v]) => v)
    ).filter( x => x );
}

var data = [
    {
        id: 1,
        title: 'foo'
    },
    {
        id: 2,
        title: 'bar'
    },
    {
        id: 3,
        title: 'bat'
    },
    {
        id: 4,
        title: 'bantz'
    },
    {
        id: 2,
        title: 'bar'
    },
    {
        id: 3,
        title: 'bat'
    }
];

console.log(getUniquesOnly(data));

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