Back when Spotify first launched in 2010, the platform came equipped with a shuffle option capable of completely randomizing the order of songs through the Fisher-Yates algorithm. It was that way in the service’s earliest years until everything changed in early 2014. In a blog post on Spotify R&D’s official Engineering site, the company announced that it was retiring its true random shuffle algorithm due to user complaints.
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In the post, Spotify explained that most users do not perceive a perfectly random order as actually random. Spotify found that customers would complain about their shuffled playlists heavily favoring songs from a particular artist instead of giving each musician space in the queue. Of course, the chance that a shuffled playlist might play a bunch of songs from one artist in a row instead of swapping between a bunch of different musicians is a natural and entirely possible consequence of true randomization — even if it doesn’t necessarily feel like it.
In response to this feedback, Spotify completely refreshed its shuffle feature. Rather than using true randomization, the new shuffle was powered by a specialized algorithm. Most of the exact details on how this algorithm was built are unknown, but the streamer did reveal that it borrowed from a principle of random sampling to create a shuffling process that would space out songs from the same artist and allow for greater song-to-song variety.
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Spotify has seldom acknowledged the existence of the newer shuffle algorithm since 2014, let alone revealed details on how it may have been altered, revised, or iterated upon in the ensuing years. However, it’s quite clear that even today, shuffle is far from a truly random experience.
