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pythonlistloopsfor-loopnested
Thistle19
Thistle19

Reputation: 37

Python - nested for loops and index out of range

I'm rather new to Python, and am running into the following error when using a nested for loop

IndexError: list index out of range

Here is my code

count = 0
count2 = 1
rlength = range(len(records))
for i in rlength:
    ex = records[count].id
    for bla in rlength:
        if re.search(ex, records[count2].id) != None:
            print records[count2].id
        count2 += 1
    count += 1
    count2 = count + 1

Edit:

Fixed with the following code

rlength = range(len(records))
for i in rlength:
    ex = records[i].id
    for bla in rlength:
        if bla + 1 < len(rlength) and re.search(ex, records[bla + 1].id) != None:
            print records[bla].id

Upvotes: 0

Views: 1478

Answers (2)

Chris_Rands
Chris_Rands

Reputation: 41168

If I understand what you are trying to do, I'm not sure you need the count and count2 at all. I think you can just use the numbers generated by your loop. I suggest using enumerate() instead of range(len()).

for i1,rlength1 in enumerate(records):
    ex = rlength1.id
    for i2,rlength2 in enumerate(records):
        if re.search(ex, rlength2.id) != None:
            print rlength2.id

Upvotes: 1

HolyDanna
HolyDanna

Reputation: 629

The loop should fail for i=1. Why ?
When i=1, count2 = 2 (= count + 1, and count = 0+1 = 1)
In the inner loop, count2 goes from 2 to 2+len(records)-1-1 (since we increment after looking at the values) = len(records)
But there is no records[len(records)] (and an index out of bound is NOT equivalent to None in python !)

Upvotes: 0

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