Dave Angel davea at ieee.org
Thu Jul 9 16:04:23 CEST 2009

You could pick a much better title.  And apparently you started a new 
thread with this one.  When responding to an existing message, you ought 
to reply-all to the existing message, rather than starting a new thread.

Tanmoy wrote:
>> Hello ,
>>          When i==0 you append an empty list to arr, so arr[i] is arr[0]. No
>> problem.
>> When i==10 you append another empty list to arr, so arr[i] is arr[10].
>> Index error because there's no arr[10], only arr[0] and arr[1].
>> Thanks for your prompt reply...
>> How can i pass this problem
>>  You could try appending to arr[-1] instead.
> Better still:
>    ...
>    row = []
>    for j in range(0,1001,1):
>          row.append(i+j)
>    arr.append(row)
>    ...
> I tried both the ways... the only thing is its not coming like 0 10
> 20.......1000 . Its coming like 0,1,2,........1000.....Any answer to the
> problem.
> Thanks
> Tanmoy Mukherjee
If you want the row to count by 10's you have to build it that way.  You 
have the arguments to the ranges backwards.  Try:

for i in range(1001):
   row = []
   for j in range(0,1010,10):

Coincidentally, once you reverse them, the original problem would go 
away.  But this is better anyway, as it makes it clear what's 
happening.  You are building 1001 rows, each containing non-contiguous 


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