列表中的随机元素

Question

Is there a way in python to select a random element form a list without considering a current element?

In other word, I want to do this

L=[1,2,3,4,5,6,7,8,9,10]
i=0
while(i<len(L):
  random.choice(L-L[i])
  i+=1

For example, at iteration 0 I do not want to have the element 1 and at iteration 1 I do not want to have the element 2 .

Answer 1

You could create a new list based on slicing:

L = [1,2,3,4,5,6,7,8,9,10]
i = 0
while i < len(L):
    random.choice(L[:i] + L[i+1:])  # L without the i-th element
    i += 1

Or simply draw a random index until you draw an index that isn't equal to i :

while i < len(L):
    while True:
        num = random.randrange(0, len(L))  # draw an index
        if num != i:                       # stop drawing if it's not the current index
            break
    random_choice = L[num]
    i += 1

If you need performance you could also just draw an index between 0 and len(L)-1 and increment it by 1 if it's equal or higher than i . That way you don't need to re-draw and index i is excluded:

while i < len(L):
    idx = random.randrange(0, len(L) - 1)
    if idx >= i:
        idx += 1                     
    random_choice = L[idx]
    i += 1

Answer 2

All you have to pick a random element other than the current index , then you can try this

l=[i for i in range(1,11)]
from random import random
for i in l:
    while 1:        
        tmp= int(random() * 10) 
        if tmp!=i:      
            print tmp
            break