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A Song Shuffling Algorithm Proposal

Real music shuffling never feels random enough. We have a biased view of what randomness is. If we shuffle a playlist and the same song plays twice in a row, we think the shuffling algorithm is broken. In reality, the song that just played had as much chance as any other song to be selected.

Shuffling a small set (like most of your playlists) is not an unknown concept for Tetris. Tetris only has 7 pieces. In versions of the game that implement real randomness (such as Sega Tetris) to select the next piece, it often feels like the game favors certain pieces. A good example is known as the drought.

Many versions of the game try to mitigate the problem by implementing algorithms that are not 100% random. In my opinion, one of the best algorithm in any Tetris game to select a piece is the one found in the Tetris: The Grand Master series.

The system involves keeping a history of the four most recent tetrominoes and trying to choose a random tetromino not in the history. Each time a piece is generated, the game will try a certain number of times to generate a tetromino that doesn’t match any in the history; if all tries fail and generate a recent piece, the game will settle with that recent piece. The overall effect is to minimize several of the same tetromino showing up in succession, while maintaining a certain amount of unpredictability. TGM1 uses 4 tries, while subsequent games using the TGM randomizer use 6 tries.” Tetris Wikia

Applying this algorithm to music, we might get something like what is described below.

I’ve implemented this algorithm in Java. The code can be found on Github.

Posted on 2018-01-15   #tetris     #java  

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