“iTunes’ available song ratings of 1 to 5 stars allow users to quickly find their favorites and help the Party Shuffle feature play more of what they like most. This article explores the algorithm iTunes uses to pick what comes next in the playlist,” Brian E. Hansen writes for OminNerd. “After hearing one artist played over and over during a shuffled play of your entire music library in iTunes you may think your player has a preference of its own. Apple claims the iTunes’ shuffle algorithm is completely random. The shuffle algorithm chooses songs ‘without replacement.’ In other words, much like going through a shuffled deck of cards, you will hear each song only once until you have heard them all… or until you have stopped the player or selected a different playlist.”
Hansen writes, “iTunes Party Shuffle is a different matter. Its algorithm selects songs ‘with replacement,’ meaning the entire deck of cards is reshuffled after each song is played. The play higher rated songs more often option does exactly what it says, but how much preference is given to higher rated songs?”
Full article here.