import and package confusion

MRAB google at mrabarnett.plus.com
Thu Apr 30 23:46:48 CEST 2009


Terry Reedy wrote:
> Dale Amon wrote:
> 
>> Now I can move on to parsing those pesky Fortran card
>> images... There wouldn't happen to be a way to take n
>> continguous slices from a string (card image) where each slice may be 
>> a different length would there? Fortran you know. No spaces between 
>> input fields. :-)
>>
>> I know a way to do it, iterating over a list of slice sizes,
> 
> Yes.
> 
>> perhaps in a list comprehension, but some of the august python 
>> personages here no doubt know better ways.
> 
> No.  Off the top of my head, here is what I would do something like 
> (untested)
> 
> def card_slice(card, sizes):
>   "Card is data input string. Sizes is an iterable of int field sizes, 
> where negatives are skipped fields.  Return list of strings."
>   pos, ret = 0, []
>   for i in sizes:
>     if i > 0:
>       ret.append(card[pos:pos+i])
>     else:
>       i = -i
>     pos += i

I would shorten that a little to:

     if i > 0:
       ret.append(card[pos:pos+i])
     pos += abs(i)

>   return ret
> 
> To elaborate this, make sizes an iterable of (size, class) pairs, where 
> class is str, int, or float (for Fortran) or other for more generel use. 
>  Then
>   ...
>   for i,c in sizes:
>     if i > 0:
>       ret.append(c(card[pos:pos+i]))
> 
> Terry Jan Reedy
> 
> -- 
> http://mail.python.org/mailman/listinfo/python-list
> 




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