JavaScript. How to change some data in object via function for array?

Question

Maybe somebody knows how to change some data in an object via a function for an array?

For example, I have an object:

var nodes = [
  { topic: "Games",    topicscore: 100},
  { topic: "Fun",      topicscore: 550},
  { topic: "New York", topicscore: 7799},
  { topic: "Hillary",  topicscore: 745},
  { topic: "Politics", topicscore: 512},
  { topic: "Trump",    topicscore: 71}
];

And I have a function:

var filterScoreValues = function(array_input){
  var a_out = [];
  array_input.forEach(function(x){
    a_out.push(Math.ceil(x / Math.max.apply(null,array_input) * 10) + 5)
  });
  return a_out;
};

How I can apply this algorithm to topicscore of my object?

I wrote this, but I want a "pretty" variant, maybe via lodash or similar:

function filterScoreValues(input){
  var array = input.map(function (i) {
    return i.topicscore;
  });

  array.forEach(function(x, index){
    input[index]['topicscore'] = Math.ceil(x / Math.max.apply(null, array) * 10) + 5;
  });

  return input;
 };

I often used loops on my variant.. :(

What are you actually trying to do? You only need to do Math.max.apply(null,array) once, not on every loop. — RobG
– RobG, Commented Dec 30, 2016 at 21:41
It would be helpful to provide the expected output from filterScoreValues method. — Erick R Soto
– Erick R Soto, Commented Dec 30, 2016 at 21:42

RomanPerekhrest · Accepted Answer · 2016-12-30 21:54:07Z

2

how to change some data in an object via a function

Use the following optimized approach(without a function. It may be wrapped into function if there would be a need to call such function multiple times):

var nodes = [
  { topic: "Games",    topicscore: 100},
  { topic: "Fun",      topicscore: 550},
  { topic: "New York", topicscore: 7799},
  { topic: "Hillary",  topicscore: 745},
  { topic: "Politics", topicscore: 512},
  { topic: "Trump",    topicscore: 71}
];

// taking max 'topicscore' at once
var max_score = Math.max.apply(null, nodes.map(function (o) {
    return o.topicscore;    
}));
// processing each 'topicscore' item in place(without creating temporary arrays)
nodes.forEach(function (o) {
    o.topicscore = Math.ceil(o.topicscore / max_score * 10) + 5;
});

console.log(nodes);

edited Dec 30, 2016 at 21:54

answered Dec 30, 2016 at 21:48

RomanPerekhrest

93.1k4 gold badges75 silver badges112 bronze badges

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

Comments

Ori Drori · Accepted Answer · 2016-12-30 21:52:32Z

Use Array#map to extract the topicscore to an array. Calculate the max once using the topicscores array. Then Array#map the topicscores array into a normalized array using max.

var nodes = [
  { topic: "Games",    topicscore: 100},
  { topic: "Fun",      topicscore: 550},
  { topic: "New York", topicscore: 7799},
  { topic: "Hillary",  topicscore: 745},
  { topic: "Politics", topicscore: 512},
  { topic: "Trump",    topicscore: 71}
];

function filterScoreValues(input){
  var topicscores = input.map(function (i) { return i.topicscore; }); // extract the topicscores to array
  
  var max = Math.max.apply(null, topicscores); // calc the max
  
  return topicscores.map(function (score) { // map normalize and return the new array
    return Math.ceil(score / max * 10) + 5;
  });
};

var result = filterScoreValues(nodes);

console.log(result);

0xcaff · Accepted Answer · 2016-12-30 21:41:41Z

0

Just use javascript:

filterScoreValues(nodes.map(node => node.topicscore));

answered Dec 30, 2016 at 21:41

0xcaff

13.8k5 gold badges52 silver badges57 bronze badges

Comments

Seb Cooper · Accepted Answer · 2016-12-30 21:55:31Z

0

Another alternative is:

var nodes = [
  { topic: "Games",    topicscore: 100},
  { topic: "Fun",      topicscore: 550},
  { topic: "New York", topicscore: 7799},
  { topic: "Hillary",  topicscore: 745},
  { topic: "Politics", topicscore: 512},
  { topic: "Trump",    topicscore: 71}
];
function filterScoreValues(input){
  var array = input.map(function (i) {
    return i.topicscore;
  });

  array.forEach(function(x, index){
    input[index].topicscore = Math.ceil(x / Math.max.apply(null, array) * 10) + 5;
  });

  return input;
 };
console.log(filterScoreValues(nodes));

answered Dec 30, 2016 at 21:55

Seb Cooper

5842 silver badges13 bronze badges

Collectives™ on Stack Overflow

JavaScript. How to change some data in object via function for array?

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related