Randomly move a certain number of items in a Python list

Question

So I've been doing some sorting algorithms and I want to run a test function that generates lists of different varieties to run my sorting algorithms on.

One such list would be an already sorted list, where n number of the items in the list have been shuffled around randomly (but not all of them, the list should still be sorted other than the n items)

testlist = random.sample(range(0,10),10)
testlist.sort()

This gives me a sorted list of unique items of size 10, but then I'm unsure how to go about moving n of these 10 items around the list to a random location, just to mix the sorting up

Answer 1

Here's one way to shuffle some items in the list:

import random
import numpy as np

# Make a sorted list of integers.
x = np.array(range(100))

# Choose 10 indices at random.
r = random.sample(range(len(x)), 10)

# Copy this list and shuffle.
s = r.copy()
random.shuffle(s)

# Replace the indices with the shuffled ones.
x[r] = x[s]

Note this might leave some indices unchanged.