.. function:: shuffle(x[, random])
- Shuffle the sequence *x* in place. The optional argument *random* is a
- 0-argument function returning a random float in [0.0, 1.0); by default, this is
- the function :func:`.random`.
+ Shuffle the sequence *x* in place.
- Note that for even rather small ``len(x)``, the total number of permutations of
- *x* is larger than the period of most random number generators; this implies
- that most permutations of a long sequence can never be generated.
+ The optional argument *random* is a 0-argument function returning a random
+ float in [0.0, 1.0); by default, this is the function :func:`.random`.
+
+ To shuffle an immutable sequence and return a new shuffled list, use
+ ``sample(x, k=len(x))`` instead.
+
+ Note that even for small ``len(x)``, the total number of permutations of *x*
+ can quickly grow larger than the period of most random number generators.
+ This implies that most permutations of a long sequence can never be
+ generated. For example, a sequence of length 2080 is the largest that
+ can fit within the period of the Mersenne Twister random number generator.
.. function:: sample(population, k)
Members of the population need not be :term:`hashable` or unique. If the population
contains repeats, then each occurrence is a possible selection in the sample.
- To choose a sample from a range of integers, use an :func:`range` object as an
+ To choose a sample from a range of integers, use a :func:`range` object as an
argument. This is especially fast and space efficient for sampling from a large
- population: ``sample(range(10000000), 60)``.
+ population: ``sample(range(10000000), k=60)``.
If the sample size is larger than the population size, a :exc:`ValueError`
is raised.