列表索引超出范围

Question

#!/usr/bin/python

import os,sys
from os import path

input = open('/home/XXXXXX/ERR001268_1', 'r').read().split('\n')

at = 1
for lines in range(0, len(input)):
    line1 = input[lines]
    line4 = input[lines+3]
    num1 = line1.split(':')[4].split()[0]
    num4 = line4.split(':')[4].split()[0]
    print num1,num4


    at += 1

However I got the error: list index out of range

What's the problem here?

btw, besides "at +=1" , is there any other way to finish this cycle loop? thx

Answer 1

The problem is that lines has a maximum value of len(input)-1 but then you let line4 be lines + 3 . So, when you're at your last couple of lines, lines + 3 will be larger than the length of the list.

for lines in range(0, len(input)):
    line1 = input[lines]
    line4 = input[lines+3]
    num1 = line1.split(':')[4].split()[0]
    num4 = line4.split(':')[4].split()[0]
    print num1,num4

Answer 2

Lets say len(input) == 10 . range(0, len(input)) iterates [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] . And when lines > 6 and you're trying to access input[lines+3 ], it clearly an IndexError, because there is no index[10] , [11] etc.

And line1.split(':')[4] can also raise an IndexError if line1.count(":") < 4 .

I didn't understand the last at part, it seems not doing anything, but you can break the loop easily with break statement.

Also, naming a variable input is a bad idea because it conflicts with builtin input function. And range(0, len(input)) == range(len(input)) , so 0 as range's first argument is unnecessary.

Answer 3

I had a similar problem and here is the solution I came up with:

tuple = (1,2,3)

dogs = [ ]

cats = [ ]

one_two = [ ]

cats.apend(tuple)

dogs.apend(tuple)

file.apend(one_two)

file.apend("/")

print file
print cats
print dogs

Have an excellent day.

Answer 4

It seems that you want to read a file and get some info from it every 3 lines. I would recommend something simpler:

def get_num(line):
    return line.split(':')[4].split()[0]

nums1 = [get_num(l) for l in open(fn, "r").readlines()]
nums2 = nums1[3:]
for i in range(len(nums2)):
    print nums1[i],nums2[i]

The last 3 numbers of nums1 won't be written. The variable at does not do anything in your code.