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Thursday, October 12, 2006

Shuffling The Deck

Who knew that the shuffle function on your iPod (or in iTunes) was so controversial? All over the internet there are conspiracy theories and accusations about the shuffling algorithm used by the Apple iSoftware.

For those of you without a strong background in maths or computer science: there is no way to generate a truly “random” number. But you can write algorithms which are close enough. But if you were unscrupulous you could put a bit of code into your algorithm that favoured some numbers over others. Or some songs.

This is what people are claiming Apple is doing with its shuffle algorithm. I don’t really buy it.

The reasoning goes that you hear a lot of some songs but not a lot of other songs. I believe this has to do with short-term thinking. I realised that I was hearing the same songs a lot but figured it would change when I added more and more songs to my iPod. What happened was the same songs kept coming up. Then over time different songs started popping up. Then these new songs were repeated.

For example a month ago I was getting a lot of The Roots and Gomez when I shuffled, now I’m getting a lot of Sleater Kinney and Minuit (and Michael Jackson). Another example is that this week I have to skip a lot of songs by Savage because they are popping up for the first time ever (and I’m skipping them because they’re not very good and I’m too lazy to delete them).

This leads me to believe (because I can’t find the actual algorithm itself) that the algorithm has the date plugged in there somewhere and it has a range of songs that have a higher chance of selection on particular dates.

Brilliant diagramImagine a bell curve with a normal distribution (see pic). The height of the graph represents likelihood of being played. In the areas are songs. So at the moment some Sleater Kinney, Minuit and Michael Jackson songs are in the middle (more likely to be played), on the outside of that are Fiona Apple, Kings of Leon and Princess Superstar songs (less likely to be played) and finally on the outskirts are The Black Seeds, Alicia Keys, and Wolfmother songs (unlikely to be played).

As the date changes the tracks move into different categories according to some undefined variables; hence why I’m suddenly getting Roots Manuva instead of Ben Harper.

Just for kicks though, here is the first ten songs I get shuffled up.

  1. For Whatever Remix – Supergroove
  2. Firecracker – Ryan Adams
  3. Kiss Me on My Neck – Erykah Badu
  4. Fruit Bubble Love – the 5.6.7.8s
  5. Circus Envy – REM
  6. All Mine (live) – Portishead
  7. Trani – Kings of Leon
  8. Everybody Needs Somebody – The Blues Brothers
  9. Whip the Blankets – Neko Case
  10. God is a Number – Sleater Kinney

Wow, notice nothing there from the list of what I thought was common other than the final track from Sleater Kinney. Random.

1 comment:

ben.run said...

People just don't understand probability!
With the number of of people who have iPods, there are very good chances that some people will get some perculiar 'non random seeming' playlists which are in fact just random.
A bit like the million monkeys and typewriters. A million ipods and.. well monkeys I suppose is apt enough.. eventually someone will probably get their playlist in alphabetical order!