Question

32

how to collate an array of dictionaries into a dictionary of arrays?

rated 0 times [ 33] [ 1] / answers: 1 / hits: 15329 / 13 Years ago, sat, september 17, 2011, 12:00:00

I have this data:

list = [

      {name:'apple', category: fruit, price: 1.22 },

      {name:'pear', category: fruit, price: 2.22 },

      {name:'coke', category: drink, price: 3.33 },

     {name:'sprite', category: drink, price: .44 },

    ];

And I'd like to create a dictionary keyed on category, whose value is an array that contains all the products of that category. My attempt to do this failed:

  var tmp = {};

    list.forEach(function(product) {

      var idx = product.category ;

      push tmp[idx], product;

    });

    tmp;

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dallasb

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2 Years ago

answered 13 Years ago krystadesiraeo · Accepted Answer

function dictionary(list) {

    var map = {};

    for (var i = 0; i < list.length; ++i) {

        var category = list[i].category;

        if (!map[category]) 

            map[category] = [];

        map[category].push(list[i].name);  // add product names only

        // map[category].push(list[i]);    // add complete products

    }

    return map;

}

var d = dictionary(list);  // call

You can test it on jsfiddle.