Question

46

How to filter a dictionary by value in JavaScript?

rated 0 times [ 53] [ 7] / answers: 1 / hits: 62544 / 8 Years ago, fri, june 3, 2016, 12:00:00

I am writing a script to create a dictionary called dict, where I store the the frequencies of some words that I have in a text area. My array looks like this:

var dict = removeArray.reduce(function(p,c) {

    if (p[c] === undefined) {

        p[c] = 1;

    } else {

        p[c]++;

    }

    return p;

}, {});

I would like to filter the elements of this dictionary by their value. I need to create a list with the words that have a value greater than one. My dictionary looks like this:

{

    92173: 6,

    C: 6,

    GJHGWO.NAYE: 1,

    GJHGX4.NAYE: 1,

    GJHGX6.NAYE: 1,

    GJHGX8.NAYE: 1,

    GJHGXA.NAYE: 1,

    GJHGXC.NAYE: 1,

    RBD: 10,

    RBD3: 2,

    SAMBORNSiPOSSSTHRa: 2,

    SAMBORNSiPOSSSTHRa1: 2,

    SAMBORNSiPOSSSTHRa2: 2,

    X: 4,

    X3: 2

}

In order to achieve that I tried using lodash, as follows:

var filtered = _.find(dict, function(user) {

    return user.frecuency > 1;

});

But I failed since I got:

undefined

I don't know how to use lodash appropriately to filter this array.

My complete code looks like this:

var splitWords = document.getElementById(texto).value.split(/[[|~]/);

var removeArray  = _.remove(splitWords, function (word) {

    return word !== '' && word !== ' ' && word !== 'n'

});



var dict = removeArray.reduce(function(p,c) {

    if (p[c] === undefined) {

        p[c] = 1;

    } else {

        p[c]++;

    }

    return p;

}, {});

console.log(dict);



var filtered = _.find(dict, function(user) {

  return user.frecuency > 1;

});



console.log(filtered)

<script src=https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js></script>

<p id=demo></p>

<textarea cols=150 rows=15 id=texto>

RBD|X|RBD3|C|92173~GJHGWO.NAYE

SAMBORNSiPOSSSTHRa1

RBD|X|RBD|C|92173~GJHGX4.NAYE

SAMBORNSiPOSSSTHRa

RBD|X3|RBD3|C|92173~GJHGX6.NAYE

SAMBORNSiPOSSSTHRa1

RBD|X|RBD|C|92173~GJHGX8.NAYE

SAMBORNSiPOSSSTHRa2

RBD|X|RBD|C|92173~GJHGXA.NAYE

SAMBORNSiPOSSSTHRa2

RBD|X3|RBD|C|92173~GJHGXC.NAYE

SAMBORNSiPOSSSTHRa

</textarea>

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benitoh

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answered 8 Years ago cristoferjordih · Accepted Answer

You could use reduce again to achieve that in plain JavaScript:

var filtered = Object.keys(dict).reduce(function (filtered, key) {

    if (dict[key] > 1) filtered[key] = dict[key];

    return filtered;

}, {});

With some ES6 features, such as arrow functions, spread syntax, Object.entries, ... it can look like this:

var filtered = Object.assign({}, ...

    Object.entries(dict).filter(([k,v]) => v>1).map(([k,v]) => ({[k]:v}))

);

Or using the newer Object.fromEntries:

var filtered = Object.fromEntries(Object.entries(dict).filter(([k,v]) => v>1));

Using Lodash

There were a few issues with your attempt with lodash:

_.find is not intended for returning an object that takes a selection of key/values from a given object. You would need _.pickBy for that.

Your object values do not have a frecuency property; they are primitive values, so you should just have to return user > 1

Lodash code:

var filtered = _.pickBy(dict, function(user) {

  return user > 1;

});