how to group an array of objects based on two properties

Question

I would like to get an array of arrays like ...[[1,2],[5,8],[9]]... depending on the group by.

This is the example I am following from the rxjs library example. This ex only uses one property to group by.

Observable.of<Obj>({id: 1, age: 5, weight: 145},
                   {id: 9, age: 7, weight: 10},
                   {id: 2, age: 5, weight: 145},
                   {id: 60, age: 11, weight: 145},
    )
    .groupBy(p => p.id)
    .flatMap( (group$) => group$.reduce((acc, cur) => [...acc, cur], []))
    .subscribe(p => console.log(p));

Expected result: [[1,2],[9],[60]]

I haven't managed to make it work with more than one property (age and weight).

Could anybody tell me how I can achieve this?

Thanks,

Nicolas Gehlert · Accepted Answer · 2018-05-25 14:15:17Z

4

you can specify a more detailed function for the group by function and return a unique key. for example age-weights. I put together a jsfiddle https://jsfiddle.net/g5pj065m/3638/

Rx.Observable.of({id: 1, age: 5, weight: 145},
    {id: 9, age: 7, weight: 10},
    {id: 2, age: 5, weight: 145},
    {id: 60, age: 11, weight: 145}
)
.groupBy(p => {
    return `${p.age}- ${p.weight}`;
})
.flatMap( (group$) => group$.reduce((acc, cur) => [...acc, cur], []))
.subscribe(p => console.log(p));

answered May 25, 2018 at 14:15

Nicolas Gehlert

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1 Comment

Aisatora Over a year ago

thanks that was great! I tried something similar but didn't work.

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