Full name
random.shuffle
Library
random
Syntax
random.shuffle(x)
Description
The random.shuffle function shuffles the sequence x in-place.
If you want to shuffle an immutable sequence x, you can use:
x = sample(x, k = len(x))
Parameters
- x: Sequence to shuffle. It must be mutable because, in any other case, the function will return an error.
Result
The random.shuffle function returns the sequence x passed as an argument shuffled.
Examples
If we have a list made up of the names of the days of the week:
days = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"]
...we could shuffle it with the following code:
random.shuffle(days)
The sequence is shuffled in-place, so we would have to print it if we wanted to see the result:
days
['Monday', 'Friday', 'Wednesday', 'Sunday', 'Saturday', 'Tuesday', 'Thursday']
Trying to shuffle an immutable sequence will return an error message. For example, if we start from a tuple:
a = ("A", "B", "C")
...trying to shuffle it generates an error:
try:
random.shuffle(a)
except:
print("Error")
random.shuffle(a)
except:
print("Error")
Error
If a complex structure is passed to this function -such as a NumPy array, for example- the results are not as expected:
import numpy as np
a = np.arange(9).reshape(3, 3)
a
a
array([[0, 1, 2],
[3, 4, 5],
[6, 7, 8]])
[3, 4, 5],
[6, 7, 8]])
random.shuffle(a)
a
a
array([[0, 1, 2],
[3, 4, 5],
[0, 1, 2]])
[3, 4, 5],
[0, 1, 2]])
