Python Error: list index out of range

Question

I keep getting the error list index out of range. I'm not sure what I'm doing wrong.

My code:

from scanner import *

def small(array):
    smallest=array[0]
    for i in range(len(array)):
        if (array[i]<smallest):
            smallest=array[i]
    return smallest

def main():
    s=Scanner("data.txt")
    array=[]
    i=s.readint()
    while i!="":
        array.append(i)
        i=s.readint()
    s.close()
    print("The smallest is", small(array))

main()

The traceback I get:

Traceback (most recent call last):
  File "file.py", line 21, in <module>
    main()
  File "file.py", line 20, in main
    print("The smallest is", small(array))
  File "file.py", line 5, in small
    smallest=array[0]
IndexError: list index out of range

You're probably passing an empty array to the small() function.. consider adding error handling for that! — msturdy
– msturdy, Commented Nov 22, 2013 at 16:41
Traceback (most recent call last): File "file.py", line 21, in <module> main() File "file.py", line 20, in main print("The smallest is", small(array)) File "file.py", line 5, in small smallest=array[0] IndexError: list index out of range — user3022573
– user3022573, Commented Nov 22, 2013 at 16:57
@user3022573: Next time, edit your question to add the traceback. I've added it in for you. — Martijn Pieters
– Martijn Pieters, Commented Nov 22, 2013 at 17:07

Martijn Pieters · Accepted Answer · 2013-11-22 16:48:42Z

5

array is empty. There is no array[0] when a list is empty.

You could test for this edgecase, perhaps:

def small(array):
    if not array:
        return None

edited Nov 22, 2013 at 16:48

answered Nov 22, 2013 at 16:41

Martijn Pieters

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Comments

Tim Pietzcker · Accepted Answer · 2013-11-22 16:42:30Z

2

Assuming the first call to .readint() returns "", then your array still is [] after the while loop, and therefore array[0] causes an IndexError.

answered Nov 22, 2013 at 16:42

Tim Pietzcker

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Comments

rdodev · Accepted Answer · 2013-11-22 16:41:38Z

1

Is likely that the array you are passing is empty. For instance, if there's an empty line or empty data in the input file.

answered Nov 22, 2013 at 16:41

rdodev

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