CODEWITHSUNDEEP
javascript
Aenaon
Aenaon

Reputation: 3593

d3.js: sort nested arrays

How can I sort the nested arrays of an array like the one below please? I would like to sort array prob and then rearrange name accordingly so that relationship is maintained.

var records = [
{ num: 1, name: ["Sam", "Amy", "John"], prob: [0.3, 0.2, 0.5]},
{ num: 2, name: ["Nick", "Carol", "Sam"], prob: [0.5, 0.03, 0.47] },
{ num: 3, name: ["Ken", "Eric", "Ely"], prob: [0.1, 0.3, 0.6] },
{ num: 4, name: ["Amy", "Sam", "John"], prob: [0.6, 0.3, 0.1] },
{ num: 5, name: ["Chris", "Donna", "Jeff"], prob: [0.25, 0.55, 0.2] }
]

I would like to end-up with:

var records = [
{ num: 1, name: ["John", "Sam", "Amy"], prob: [0.5, 0.3, 0.2]},
{ num: 2, name: ["Nick", "Sam", "Carol"], prob: [0.5, 0.47, 0.03] },
{ num: 3, name: ["Ely", "Eric", "Ken"], prob: [0.6, 0.3, 0.1] },
{ num: 4, name: ["Amy", "Sam", "John"], prob: [0.6, 0.3, 0.1] },
{ num: 5, name: ["Donna", "Chris", "Jeff"], prob: [0.55, 0.25, 0.2] }
]

Thanks!

Upvotes: 1

Views: 610

Answers (3)

i alarmed alien
i alarmed alien

Reputation: 9530

It's easiest if you turn your arrays of names and probs into objects to preserve the links between each name and the probability. The object's properties can then be sorted as if they were an array using a custom sort function.

records.forEach( function (d) {
  var temp = {};

  // create objects with key <name> and value <prob>
  // (this makes the assumption that prob values may not be unique, but names are)
  d.name.forEach( function(e,i) {
    temp[e] = d.prob[i];
  })

  // get an array of the object keys (the name), and sort them by the object values
  // (the corresponding prob), descending. Replace the existing `name` array with this.
  d.name = Object.keys(temp).sort(function(a, b){ 
    return temp[b] - temp[a];
  });

  // sort the prob values in descending order (with d3.descending, since you mentioned d3)
  d.prob = d.prob.sort(function(a,b){ return b - a; });
});

If you aren't using d3, replace d3.descending with the standard descending sort function.

Upvotes: 1

Emeeus
Emeeus

Reputation: 5260

Here a solution: we could store names and prob in pairs and sorting both values at the same time, then we assign that names and probs sorted to the main object:

var records = [
{ num: 1, name: ["Sam", "Amy", "John"], prob: [0.3, 0.2, 0.5]},
{ num: 2, name: ["Nick", "Carol", "Sam"], prob: [0.5, 0.03, 0.47] },
{ num: 3, name: ["Ken", "Eric", "Ely"], prob: [0.1, 0.3, 0.6] },
{ num: 4, name: ["Amy", "Sam", "John"], prob: [0.6, 0.3, 0.1] },
{ num: 5, name: ["Chris", "Donna", "Jeff"], prob: [0.25, 0.55, 0.2] }
];

var pairs = records.map((e,i)=>
e.name.map((e2,i2)=>[e2,records[i].prob[i2]]).sort((a,b)=>b[1]-a[1])
);

records.map((e, i) => {
  e.name = pairs[i].map(o => o[0])
  e.prob = pairs[i].map(o => o[1])      
})

console.log(records)

Upvotes: 1

rioV8
rioV8

Reputation: 28838

Refactoring Emeeus answer

var records = [
{ num: 1, name: ["Sam", "Amy", "John"], prob: [0.3, 0.2, 0.5]},
{ num: 2, name: ["Nick", "Carol", "Sam"], prob: [0.5, 0.03, 0.47] },
{ num: 3, name: ["Ken", "Eric", "Ely"], prob: [0.1, 0.3, 0.6] },
{ num: 4, name: ["Amy", "Sam", "John"], prob: [0.6, 0.3, 0.1] },
{ num: 5, name: ["Chris", "Donna", "Jeff"], prob: [0.25, 0.55, 0.2] }
];

records.forEach((e, i) => {
  var el = e.name.map((e2,i2)=>[e2,e.prob[i2]]);
  el.sort((a, b) => b[1] - a[1]);
  e.name = el.map(o => o[0]);
  e.prob = el.map(o => o[1]);
});

console.log(records);

Upvotes: 1

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