Selecting random items from Javascript nested array / data structure

Question

I'm looking for advice on whether this is the best data structure for what Im trying to achieve, and if so, how I would create a function that chooses a song at random.

var song = {

    john: [ "Come Together", "Revolution" ],
    paul: [ "Hey Jude", "Blackbird" ],
    george: [ "Something", "Here Comes the Sun" ],
    ringo: [ "Yellow Submarine", "With a Little Help from my Friends" ]
};

Here's how it will work:

Timer begins when the user clicks start
A song (picked at random), is displayed onscreen
User then clicks one of four icons/names (john, paul, george or ringo)
Answer is logged (correct or incorrect).
Another song is picked at random until the timer finishes.

I don't want a solution to this problem, I just want to know if I'm using the best data structure...and if I am (or if I'm not!), how I'd go about generating a random song. I'm new to this and what I'm trying to do is way more complicated than anything I've tried before. Final point...John and Paul's individual arrays are going to be pretty damn long when the song list is complete...

Thanks!

I think this is a better question for softwareengineering.stackexchange.com — Sumner Evans
– Sumner Evans, Commented Nov 18, 2016 at 17:19
I think using an array of songs that have two properties: title and author would make it easier for your purposes. — user2345
– user2345, Commented Nov 18, 2016 at 17:19
Do you always have exactly two songs per artist? Are you wanting there to be an equal probability that any song is chosen, or that any artist is chosen (in cases where artists have different numbers of songs) (and then a random song from that artist)? From a testing point of view it should be that there is an equal probability of selecting each artist regardless of the number of songs per artist. If that is not the case, then guessing the artist based on the one with the most songs can become a viable test taking strategy. — Makyen
– Makyen ♦, Commented Nov 18, 2016 at 17:46
I intend to put the full Beatles back catalogue into the array, so it will be hundreds of songs long (the game will actually track who is on lead vocal, not authorship of the song). John and Paul will be have the vast majority, so ringo and george's arrays will be quite short in comparison. I did think about having author:title as the the key:value, but I was thinking ahead and trying to keep the code as short as possible - if john has 200 songs say, I'd have to write those key:value pairs out for each song - the way I wrote the array above, each vocalist only gets written once. — Sean Doherty
– Sean Doherty, Commented Nov 18, 2016 at 17:54
@SumnerEvans when referring other sites, it is often helpful to point that cross-posting is frowned upon — gnat
– gnat, Commented Nov 18, 2016 at 18:16

000 · Accepted Answer · 2016-11-18 17:22:10Z

1

I would recommend using a relational structure.

var artists = ['john', 'paul', 'george', 'ringo'];
var songs = [
  { name: "Come Together", artist: 0 },
  { name: "Revolution", artist: 0 },
  { name: "Hey Jude", artist: 1 },
  { name: "Blackbird", artist: 1 },
  { name: "Something", artist: 2 }
];

This allows you to add more properties to the artists if you need (like a picture, wikipedia link, etc).
It allows a faster lookup of the artist given a song. Your current setup would require a big cost to find the artist given a song.
It is easier to randomly, uniformly, pick a random song. Your current setup would make it difficult to pick a song randomly and uniformly.

answered Nov 18, 2016 at 17:22

000

27.3k10 gold badges74 silver badges103 bronze badges

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

1 Comment

Sean Doherty Over a year ago

Thanks Joe. I'm actually a fair way of testing this yet but this seems to make sense.

Sumner Evans · Accepted Answer · 2016-11-18 17:21:38Z

1

I would use an array of songs, each of which has an author:

You could then find all of the songs with a given author using filter():

var songs = [{
  author: 'john',
  title: 'Come Together'
}, {
  author: 'paul',
  title: 'Hey Jude'
}, ];


var johnsSongs = songs.filter(function(song) {
  return song.author === 'john';
});
             
console.log(johnsSongs);

answered Nov 18, 2016 at 17:21

Sumner Evans

9,2055 gold badges32 silver badges48 bronze badges

1 Comment

Sean Doherty Over a year ago

Thanks Sumner. I think the problem with this solution is if my song list runs into the 100s, then I have to write those author:title pairs for each song.

Collectives™ on Stack Overflow

Selecting random items from Javascript nested array / data structure

2 Answers 2

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related