loop through each line in a text file

[Alf P. Steinbach]

* qtrimble:
> I'm a python newbie but I do have some basic scripting experience.  I
> need to take the line starting with "wer" and extract the year and day
> of year from that string.  I want to be able to add the year and day
> of year from the last line having "wer*" to the lines occurring in
> between "wer*" lines.  Python seems suitable to do this and I'm fairly
> certain I can eventually get this to work but I've been hit with a
> very short time frame so I'm looking for any generous help.  The data
> below is just a sample.  There are well over 500,000 lines that need
> processed.
> 
> wer1999001
>       31.2234      82.2367
>       37.9535      82.3456
> wer1999002
>       31.2234      82.2367
>       37.9535      82.3456

<example>
   >>> line = "wer1999001"
   >>> line
   'wer1999001'
   >>> line[3:3+4]
   '1999'
   >>> line[7:7+3]
   '001'
   >>> _
</example>

Cheers & hth.,

- Alf