Use the resultant list of a while loop as a condition for the loop itself

Question

So lets say I have a a function defined like

def function(x):
    list1 = []
    while list1[-1] < x:
       ... (loop will generate a list of ints)
    return list1

The while loop will generate a list of ints, and I want the while loop to run until the last element of the list being generated is < x.

I tried something like while list1[-1] < x but obviously it returns an error on the first cycle because the list is empty at the beginning and the index is out of range.

Duplicate of this: http://stackoverflow.com/questions/8429794/how-to-fill-a-list — Robert Moskal, Nov 10 '14 at 02:38
@RobertMoskal Not quite. Take another look at what he is asking. — , Nov 10 '14 at 02:41
@sapcing can you define *last element of the list being * qhile your list is empty initially. — Vishnu Upadhyay, Nov 10 '14 at 03:00
This raise an IndexError because you are trying to fetch the last of an empty list. I believe what you need is a recursive function. — Burhan Khalid, Nov 10 '14 at 03:01

score 3 · Accepted Answer · answered Nov 10 '14 at 05:40

Just put a condition if the list is empty in the begin of the loop:

import random
def function(x):
    list1 = []
    while len(list1) == 0 or list1[-1] < x:
        list1.append(random.randint(0,100))
    return list1

print function(100)

[76, 36, 75, 97, 10, 14, 33, 28, 20, 29, 61, 60, 79, 53, 76, 28, 100]

Use the resultant list of a while loop as a condition for the loop itself

1 Answers1