Mutating array of objects into array of chunked arrays containing objects with common property

Question

I have an array of objects that all contain a property snail.

I'd like to mutate this array into an array of arrays, with each element array containing objects that have a common property snail

It is very similar to lodash _.partition, except it needs to happen an indeterminate number of times, recursively, and be on a flat level and not deeply nested.

Thank you for any guidance.

Here is a sample data structure: [ { hi: "bungalo" }, { hi: 'bodego' }, { hi: 'bodego' }, { hi: 'pet rock' } ]

[ [ { snail: 'big' }, { snail: 'big' } ], [ {snail: 'small' }, {snail: 'small'} ] ]

Ah it helps to write it out sometimes - I could use _.flatten to solve the problem of nesting. But I still need to write my first recursive function! — realisation
– realisation, Commented Jan 12, 2016 at 5:43
It would be useful to post a sample of the data structure, it's pretty vague as it stands. — Evan Trimboli
– Evan Trimboli, Commented Jan 12, 2016 at 5:45
Its super simple. [ { hi: "bungalo" }, { hi: 'bodego' }, { hi: 'bodego' }, { hi: 'pet rock' } ] — realisation
– realisation, Commented Jan 12, 2016 at 5:46
Question not clear... what do you expect as output? And why do you need to mutate? — elclanrs
– elclanrs, Commented Jan 12, 2016 at 5:52
with respect to the sample data structure can you also post the sample output expected? I am still confused about your question. — Yogesh Patil
– Yogesh Patil, Commented Jan 12, 2016 at 5:54

NicBright · Accepted Answer · 2016-01-12 07:33:37Z

1

I've played a little bit and created the following snippet which does what you're looking for in two different ways, the second one being more elegant I think:

var data = [ { snail: "bungalo", i: 1 }, { snail: 'bodego', i: 2 }, { snail: 'bodego', i: 3 }, { snail: 'pet rock', i: 4 }, { snail: "bungalo", i: 5 } ];

var multiPartitioned = _(data).uniq('snail').pluck('snail').map(function(snail) {
  return _.filter(data, 'snail', snail);
}).value();

var multiPartitionedMoreElegant = _(data).groupBy('snail').values().value();

console.log(multiPartitioned);
console.log(multiPartitionedMoreElegant);

You can see this example on CodePen: http://codepen.io/NicBright/pen/VeWXpj?editors=001

Regards, Nicolas

edited Jan 12, 2016 at 7:33

answered Jan 12, 2016 at 7:14

NicBright

8,0095 gold badges21 silver badges21 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

realisation Over a year ago

ah, group by! that did it. I didn't think I needed recursion at first, but didn't see this group by. Obviously need to get more familiar with lodash chaining & .value().

6502 · Accepted Answer · 2016-01-12 07:27:18Z

1

What about the dead simple:

bysnail = {};
objects.forEach(function(x){
    (bysnail[x.snail] || (bysnail[x.snail] = [])).push(x);
});

?

The output is an object mapping snail values to the list of objects with that value.

answered Jan 12, 2016 at 7:27

6502

115k17 gold badges177 silver badges277 bronze badges

1 Comment

realisation Over a year ago

That works, except for this application I need an array inside an array for the ordering in ng-repeats

Collectives™ on Stack Overflow

Mutating array of objects into array of chunked arrays containing objects with common property

2 Answers 2

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related