Geek Answers Handbook

Underscore.js converts an object to an array

I am relatively new to underscore.js and I have an object included in the REST service that looks like this (I typed it manually and assigned it var here):

var production = [
    {key: ["wind", "1"], value: 5},
    {key: ["wind", "2"], value: 9},
    {key: ["wind", "3"], value: 11},
    {key: ["wind", "4"], value: 7},
    {key: ["solar", "1"], value: 1},
    {key: ["solar", "2"], value: 1},
    {key: ["solar", "3"], value: 2},
    {key: ["solar", "4"], value: 3},
    {key: ["oil", "1"], value: 15},
    {key: ["oil", "2"], value: 16},
    {key: ["oil", "3"], value: 22},
    {key: ["oil", "4"], value: 23},
];

Then even further, I have code that parses this object and creates arrays for such elements:

var orderedProduction = _.chain(production)
      .groupBy(function (entity) {
            return entity.key[0];
      })
      .map(function (values) { 
            return _.map(values, function (entity2) {
                  return entity2.value;
            });
      })
      .value();

This gives the following results:

orderedProduction  = [
  [5, 9, 11, 7],
  [1, 1, 2, 3],
  [15, 16, 22, 23]
]

Which loses keys (wind / sun / oil). And used to draw a graph. I can also check if some of these arrays match a specific threshold:

var threshold = _.map(orderedProduction  , function(arr) {
    return _.max(arr) > 10;
});

My requirements are now changed, and now I need to filter out these arrays for the total amount, keeping the key.

What would I like to do with such an object:

orderedProduction  = {
      "wind": [5, 9, 11, 7],
      "solar": [1, 1, 2, 3],
      "oil": [15, 16, 22, 23]
    }

, , . (.. , 10).

jsfiddle, , : http://jsfiddle.net/2mfjw3jk/

UPDATE: , , :

var orderedProduction = _.chain(production)
    .groupBy(function (entity) {
        return entity.key[0];
    })
    .map(function (vals, key) {
        return [key, _.pluck(vals, 'value')]
    })
    .filter(function(arr) {
        var sum = 0;
        _.each(arr[1], function(num){
            sum += num;
        })
        return sum > 10;
    })
    .object()
    .value();

( 10).

+4
3

:

var orderedProduction = _.chain(production)
    .groupBy(function (entity) {
        return entity.key[0];
    })
    .map(function (vals, key) {
        return [key, _.pluck(vals, 'value')]
    })
    .object()
    .value();


{ wind: [ 5, 9, 11, 7 ],
  solar: [ 1, 1, 2, 3 ],
  oil: [ 15, 16, 22, 23 ] }
+6

map(), javascript. _Map() . , :

var obj = {};
production.map(function(data) {
    if(data.key[0] in obj) {
        obj[data.key[0]] += data.value;
    } else {
        obj[data.key[0]] = 0;
        obj[data.key[0]] += data.value;
    }
});
console.log(obj);

, , , . , (, "" ) obj . , 0, .

, .

+2

This is probably not the most efficient code, but it does the job using underscores.

Live Demo

var production = [
    {key: ["wind", "1"], value: 5},
    {key: ["wind", "2"], value: 9},
    {key: ["wind", "3"], value: 11},
    {key: ["wind", "4"], value: 7},
    {key: ["solar", "1"], value: 1},
    {key: ["solar", "2"], value: 1},
    {key: ["solar", "3"], value: 2},
    {key: ["solar", "4"], value: 3},
    {key: ["oil", "1"], value: 15},
    {key: ["oil", "2"], value: 16},
    {key: ["oil", "3"], value: 22},
    {key: ["oil", "4"], value: 23}
];

var orderedProduction =  _.chain(production)
    .groupBy(function (entity) {
        return entity.key[0];
    })
    .map(function(items, key){
        var returnVal = [key]; 
        var total = 0; 
        returnVal.push(_.map(items, function(obj){
            total += obj.value; 
            return obj.value; 
        })); 

        if(total > 10){
            return returnVal; 
        }

    })
    .filter(function(num) {
        return num !== undefined;
    })
    .object()
    .value();

console.log(production);
console.log(orderedProduction);
+1
source

More articles:


All Articles