On 09/08/2012 06:02 AM, tinn...@isbd.co.uk wrote:
> Dave Angel <d...@davea.name> wrote:
>> Would you like to define "exists" ? A list is not sparse, so all items
>> exist if their subscript is less than the length of the list. So all
>> you need to do is compare 2 to len(fld).
>>
> Yes, a I said a simple len(fld) will tell me if fld[2] 'exists' but it
> gets messy if I have to do it in the middle of the print sequence.
>
>
>> But perhaps there's another approach. Just what DO you want to print if
>> fld(1) exists, but fld(2) does not? Do you still want to print out day,
>> fld(1), and balance? Or do you want to skip balance as well?
>>
> Here's a sample of the file whose lines are being split() :-
>
> 01 JB 0.00 Start of 2012, Initial balance
> 02 BB 0.00
> 13 ZB 0.00
>
> I want to print out everything, it's just that in some cases there's
> no descriptive text (the bit that ends up in fld[2]).
>
>
>> if you literally want nothing printed for list elements beyond the end,
>> then I'd add some extra empty-strings to the end of the list.
>>
>> fld.extend("" * 5)
>>
>> Now, subscripts 0 through 4 inclusive will work, as specified.
>>
> That's probably the simplest approach, thank you.
>
If there literally is only one missing field, and at the end, then you
could use fld.append("") instead. Or better, you could do something like
if len(fld) == 2 : fld.append(""")
This may be longer, but at least it's in one place -- the place where
the split is occurring. And it pretty much states that the fld2 is
optional.
You ought to consider what error to report if you encounter a line with
missing fields that ARE required.
--
DaveA
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