Implementation of lazy Fisher-Yates shuffle using a binary tree to manage struck entries. The principal class is Shuffler, which maps an index to a value and vice versa, where the association between an index and a value is randomly determined the first time the index-to-value mapping is requested. The reverse value-to-index mapping is possible only after the corresponding index-to-value mapping is determined.
pip install lazy-fisher-yates-shuffler"""
Sample code.
"""
from lazy_fisher_yates_shuffler import Shuffler
# Construct a 1,000-element non-cyclic shuffler.
shuffler = Shuffler(1000, False)
# Determine the value at a given index.
index = 10
value = shuffler.value_at(index)
print(value)
# Shuffler is reversible.
assert index == shuffler.index_of(value)
# Iterate over the entire range of the shuffler (0-999).
# Values will be randomly distributed and no two will be identical.
for value in shuffler:
print(value)
# Construct a 1,000-element cyclic shuffler.
shuffler = Shuffler(1000, True)
# Iterate over the entire range of the shuffler (0-999).
# Values will be randomly distributed and cyclic: each value is the index of the next value.
# Last value is first index (0).
for value in shuffler:
print(value)