Filtering through a multidimensional array using underscore.js

Question

I have an array of event objects called events. Each event has markets, an array containing market objects. Inside here there is another array called outcomes, containing outcome objects.

I want to use Underscore.js or some other method to find all of the events which have markets which have outcomes which have a property named test.

I imagine this would be achieved using a series of filters but I didn't have much luck!

Is there any inverse reference? I mean from outcome to market and so on. Because in this case you can just filter all the outcome objects those match your search and go backwards until the event, then clean up the array for unique elements. — fguillen
– fguillen, Commented May 30, 2012 at 18:00

McGarnagle · Accepted Answer · 2014-04-15 14:37:24Z

14

I think you can do this using the Underscore.js filter and some (aka "any") methods:

// filter where condition is true
_.filter(events, function(evt) {

    // return true where condition is true for any market
    return _.any(evt.markets, function(mkt) {

        // return true where any outcome has a "test" property defined
        return _.any(mkt.outcomes, function(outc) {
            return outc.test !== undefined ;
        });
    });
});

edited Apr 15, 2014 at 14:37

answered May 30, 2012 at 18:03

McGarnagle

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2 Comments

Fasani Over a year ago

I think maybe the user means lodash.js, as I don't see an _.any method in underscore.js lodash.com

McGarnagle Over a year ago

@Fasani it is Underscore, not Lodash. _.any is an alias for _.some: underscorejs.org/#some

Bergi · Accepted Answer · 2012-05-30 18:08:35Z

3

No need for Underscore, you could do this with native JS.

var events = [{markets:[{outcomes:[{test:x},...]},...]},...];
return events.filter(function(event) {
    return event.markets.some(function(market) {
        return market.outcomes.some(function(outcome) {
            return "test" in outcome;
        });
    });
});

Yet of course you could also use the corresponding underscore methods (filter/select and any/some).

answered May 30, 2012 at 18:08

Bergi

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Comments

qwertymk · Accepted Answer · 2012-05-30 18:09:39Z

0

Try this:

_.filter(events, function(me) { 
    return me.event && 
        me.event.market && me.event.market.outcome && 
        'test' in me.event.market.outcome
});

DEMO

edited May 30, 2012 at 18:09

answered May 30, 2012 at 18:04

qwertymk

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Comments

webjay · Accepted Answer · 2014-10-21 22:25:22Z

var events = [
  {
    id: 'a',
    markets: [{
      outcomes: [{
        test: 'yo'
      }]
    }]
  },
  {
    id: 'b',
    markets: [{
      outcomes: [{
        untest: 'yo'
      }]
    }]
  },
  {
    id: 'c',
    markets: [{
      outcomes: [{
        notest: 'yo'
      }]
    }]
  },
  {
    id: 'd',
    markets: [{
      outcomes: [{
        test: 'yo'
      }]
    }]
  }
];

var matches = events.filter(function (event) {
  return event.markets.filter(function (market) {
    return market.outcomes.filter(function (outcome) {
      return outcome.hasOwnProperty('test');
    }).length;
  }).length;
});

matches.forEach(function (match) {
  document.writeln(match.id);
});

Here's how I would do it, without depending on a library:

var matches = events.filter(function (event) {
  return event.markets.filter(function (market) {
    return market.outcomes.filter(function (outcome) {
      return outcome.hasOwnProperty('test');
    }).length;
  }).length;
});

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