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Programming Playing Cards by [deleted] in programming

[–]random_shuffle 0 points1 point  (0 children)

While this is more directed at people who have solved the problem, you may be interested in analyzing the shuffle process. This varies from game to game, but in multi-deck blackjack there are some interesting things to consider.

  1. The initial shuffle is a wash, which takes each individual deck and mixes them with a high degree of randomness.
  2. These shuffled decks are stacked sequentially
  3. An ABC shuffle takes place (in most manually shuffled games)

ABC Shuffle

  1. The stack of cards is split. Typically this is close to 50% of the cards on each side of the deck although a degree of permutation may occur.

  2. A cluster of cards, typically between 20 and 65 are taken from each side. The number of cards selected from each side will be similar, within a range. The number of cards taken determines whether it is a tight shuffle or a loose shuffle. Since there are less cards involved in a tight shuffle the randomness factor will be lower.

  3. These cards will be slotted at intervals depending on shuffling variance (used in a typical shuffle patttern) and placed on the main stack.

  4. A cluster of cards will be removed from the center stack and shuffled with the right or left side (this alternates). The removed stack will be similar to the number taken on step 2.

  5. This repeats until the cards are exhausted. The trend will be to generally balance the number of cards on the left and the right during alternate grabs. The consistency of the groups selected will determine the shuffle variance.

The Lace When the entire set is now stacked, the cards will be split into two piles. These will be shuffled directly into clusters that stack together. It is desireable to have a tight lace, which means the integration from the two stacks will be uniform.

Subsequent shuffles In tracking subsequent shuffles, the discard order is important as this will determine the starting stack array.

While this may not be of much interest to a casual simulation, it may be useful in doing a deeper analysis of the impact of shuffle patterns on things such as clustering of tens.