Shuffling a list of objects
random.shuffle should work. Here's an example, where the objects are lists:
from random import shufflex = [[i] for i in range(10)]shuffle(x)# print(x) gives [, , , , , , , , , ]# of course your results will vary
Note that shuffle works in place, and returns None.
As you learned the in-place shuffling was the problem. I also have problem frequently, and often seem to forget how to copy a list, too. Using
sample(a, len(a)) is the solution, using
len(a) as the sample size. See https://docs.python.org/3.6/library/random.html#random.sample for the Python documentation.
Here's a simple version using
random.sample() that returns the shuffled result as a new list.
import randoma = range(5)b = random.sample(a, len(a))print a, b, "two list same:", a == b# print: [0, 1, 2, 3, 4] [2, 1, 3, 4, 0] two list same: False# The function sample allows no duplicates.# Result can be smaller but not larger than the input.a = range(555)b = random.sample(a, len(a))print "no duplicates:", a == list(set(b))try: random.sample(a, len(a) + 1)except ValueError as e: print "Nope!", e# print: no duplicates: True# print: Nope! sample larger than population