Conditionally remove duplicates from array

Question

I have an array that looks like this

[
    {
        topic: 'Topic 1',
        person: { ... },
        unit: 'ABC-DEF'
    },
    {
        topic: 'Topic 1',
        person: { ... },
        unit: 'ABC'
    },
    {
        topic: 'Topic 1',
        person: { ... },
        unit: 'ABC-123-DEF'
    },
    {
        topic: 'Topic 2',
        person: { ... },
        unit: 'ABC-123'
    }
]

"units" are organisational units in my company. If there are duplicates by topic I want to keep only the object with the shortest unit and remove all others. So the example from above becomes:

[
    {
        topic: 'Topic 1',
        person: { ... },
        unit: 'ABC'
    },
    {
        topic: 'Topic 2',
        person: { ... },
        unit: 'ABC-123'
    }
]

I already took a look at uniqBy from lodash but how can I make sure that only the duplicate with the shortest unit stays in the array?

georg · Accepted Answer · 2018-02-26 11:17:32Z

1

uniqBy keeps the first item it finds, so just sort by unit.length before filtering:

_.uniqBy(_.sortBy(data, x => x.unit.length), 'topic')

answered Feb 26, 2018 at 11:17

georg

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georg · Accepted Answer · 2018-02-26 12:35:44Z

1

Though this question is already answered, I tried it using native javascript APIs (in case someone wants to do it without using lodash)-

I used sort to sort the array according to shortest unit.

And then grouped them by topic and chose first item as item with shortest unit (because it was sorted in first step).

Checkout this code -

var finalData = [];
var data = [
    {
        topic: 'Topic 1',
        person: {  },
        unit: 'ABC-DEF'
    },
    {
        topic: 'Topic 1',
        person: { },
        unit: 'ABC'
    },
    {
        topic: 'Topic 1',
        person: { },
        unit: 'ABC-123-DEF'
    },
    {
        topic: 'Topic 2',
        person: { },
        unit: 'ABC-123'
    }
];

data.sort((item1, item2) => {
    return item1.unit.length - item2.unit.length;
}).reduce(function(groups, item) {
    if (!groups[item.topic]) {
        finalData.push(item);
        groups[item.topic] = true;
    }
    return groups;
  }, {});
  
console.log(finalData);

I hope this helps :)

edited Feb 26, 2018 at 12:35

georg

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answered Feb 26, 2018 at 11:49

planet_hunter

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1 Comment

georg Over a year ago

I fixed a couple of mistakes in your code, hope you don't mind.

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